Dubbo2.7源码详解
Spring与Dubbo整合原理与源码分析
【1】注解@EnableDubbo
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
@EnableDubboConfig // @EnableDubboConfig注解用来将properties文件中的配置项转化为对应的Bean
@DubboComponentScan // @DubboComponentScan注解用来扫描服务提供者和引用者(@Service与@Reference)
public @interface EnableDubbo {
@AliasFor(annotation = DubboComponentScan.class, attribute = "basePackages")
String[] scanBasePackages() default {};
@AliasFor(annotation = DubboComponentScan.class, attribute = "basePackageClasses")
Class<?>[] scanBasePackageClasses() default {};
@AliasFor(annotation = EnableDubboConfig.class, attribute = "multiple")
boolean multipleConfig() default true;
}【2】注解@EnableDubboConfig
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
@Import(DubboConfigConfigurationRegistrar.class)
public @interface EnableDubboConfig {
boolean multiple() default true;
}1）DubboConfigConfigurationRegistrar类的作用
//因为实现了ImportBeanDefinitionRegistrar接口，spring容器就会实例化该类，并且调用其registerBeanDefinitions方法；
public class DubboConfigConfigurationRegistrar implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
//执行DubboConfigConfigurationRegistrar;
AnnotationAttributes attributes = AnnotationAttributes.fromMap(
importingClassMetadata.getAnnotationAttributes(EnableDubboConfig.class.getName()));
boolean multiple = attributes.getBoolean("multiple"); //默认值是true
// Single Config Bindings
registerBeans(registry, DubboConfigConfiguration.Single.class);
if (multiple) { // Since 2.6.6 https://github.com/apache/dubbo/issues/3193
registerBeans(registry, DubboConfigConfiguration.Multiple.class);
}
}
}2）registerBeans做了什么
public static void registerBeans(BeanDefinitionRegistry registry, Class<?>... annotatedClasses) {
if (ObjectUtils.isEmpty(annotatedClasses)) {
return;
}
...
AnnotatedBeanDefinitionReader reader = new AnnotatedBeanDefinitionReader(registry);
...
// 利用Spring中的AnnotatedBeanDefinitionReader来解析annotatedClasses
// 会解析该类上的注解，然后进行处理
reader.register(annotatedClasses);
}3）DubboConfigConfiguration类展示
public class DubboConfigConfiguration {
/**
* Single Dubbo {@link AbstractConfig Config} Bean Binding
*/
@EnableDubboConfigBindings({
@EnableDubboConfigBinding(prefix = "dubbo.application", type = ApplicationConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.module", type = ModuleConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.registry", type = RegistryConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.protocol", type = ProtocolConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.monitor", type = MonitorConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.provider", type = ProviderConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.consumer", type = ConsumerConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.config-center", type = ConfigCenterBean.class),
@EnableDubboConfigBinding(prefix = "dubbo.metadata-report", type = MetadataReportConfig.class),
@EnableDubboConfigBinding(prefix = "dubbo.metrics", type = MetricsConfig.class)
})
public static class Single {}
/**
* Multiple Dubbo {@link AbstractConfig Config} Bean Binding
*/
@EnableDubboConfigBindings({
@EnableDubboConfigBinding(prefix = "dubbo.applications", type = ApplicationConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.modules", type = ModuleConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.registries", type = RegistryConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.protocols", type = ProtocolConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.monitors", type = MonitorConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.providers", type = ProviderConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.consumers", type = ConsumerConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.config-centers", type = ConfigCenterBean.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.metadata-reports", type = MetadataReportConfig.class, multiple = true),
@EnableDubboConfigBinding(prefix = "dubbo.metricses", type = MetricsConfig.class, multiple = true)
})
public static class Multiple {}
}4）那么必然又会解析到@EnableDubboConfigBindings注解
//又是利用了实现了ImportBeanDefinitionRegistrar接口，在实例化该类会调用其registerBeanDefinitions方法；
public class DubboConfigBindingsRegistrar implements ImportBeanDefinitionRegistrar, EnvironmentAware {
private ConfigurableEnvironment environment;
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
//执行DubboConfigBindingsRegistrar
AnnotationAttributes attributes = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(EnableDubboConfigBindings.class.getName()));
// 拿到多个@EnableDubboConfigBinding注解
AnnotationAttributes[] annotationAttributes = attributes.getAnnotationArray("value");
DubboConfigBindingRegistrar registrar = new DubboConfigBindingRegistrar();
//将环境变量注入
registrar.setEnvironment(environment);
for (AnnotationAttributes element : annotationAttributes) {
// 逐个解析@EnableDubboConfigBinding注解，比如@EnableDubboConfigBinding(prefix = "dubbo.application", type = ApplicationConfig.class)
registrar.registerBeanDefinitions(element, registry);
}
}
@Override
public void setEnvironment(Environment environment) {
Assert.isInstanceOf(ConfigurableEnvironment.class, environment);
this.environment = (ConfigurableEnvironment) environment;
}
}5）registrar.registerBeanDefinitions方法的调用情况
public class DubboConfigBindingRegistrar implements ImportBeanDefinitionRegistrar, EnvironmentAware {
private final Log log = LogFactory.getLog(getClass());
private ConfigurableEnvironment environment;
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
//执行DubboConfigBindingRegistrar
AnnotationAttributes attributes = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(EnableDubboConfigBinding.class.getName()));
registerBeanDefinitions(attributes, registry);
}
protected void registerBeanDefinitions(AnnotationAttributes attributes, BeanDefinitionRegistry registry) {
// prefix = "dubbo.application"
String prefix = environment.resolvePlaceholders(attributes.getString("prefix"));
// type = ApplicationConfig.class
Class<? extends AbstractConfig> configClass = attributes.getClass("type");
boolean multiple = attributes.getBoolean("multiple");
//针对配置分别进行注册成Bean对象，方法1
registerDubboConfigBeans(prefix, configClass, multiple, registry);
}
//方法1，因为Single和Multiple都是走同一套逻辑，采用参数boolean multiple区分
private void registerDubboConfigBeans(String prefix, Class<? extends AbstractConfig> configClass, boolean multiple, BeanDefinitionRegistry registry) {
// 从properties文件中根据前缀拿对应的配置项，比如根据dubbo.application前缀，
// 就可以拿到如下配置：
// dubbo.application.name=dubbo-demo-provider-application
// dubbo.application.logger=log4j
Map<String, Object> properties = getSubProperties(environment.getPropertySources(), prefix);
// 如果没有相关的配置项，则不需要注册BeanDefinition
if (CollectionUtils.isEmpty(properties)) {
if (log.isDebugEnabled()) {
log.debug(...);
}
return;
}
// 根据配置项生成beanNames，为什么会有多个？
// 普通情况一个dubbo.application前缀对应一个ApplicationConfig类型的Bean
// 特殊情况下（配置两种协议），比如dubbo.protocols对应了：
// dubbo.protocols.p1.name=dubbo
// dubbo.protocols.p1.port=20880
// dubbo.protocols.p1.host=0.0.0.0
// dubbo.protocols.p2.name=http
// dubbo.protocols.p2.port=8082
// dubbo.protocols.p2.host=0.0.0.0
// 那么就需要对应两个ProtocolConfig类型的Bean，那么就需要两个beanName:p1和p2
// 这里就是multiple为true或false的区别，名字的区别，根据multiple用来判断是否从配置项中获取beanName
// 如果multiple为false，则看有没有配置id属性，如果没有配置则自动生成一个beanName.
Set<String> beanNames = multiple ? resolveMultipleBeanNames(properties) : Collections.singleton(resolveSingleBeanName(properties, configClass, registry));
for (String beanName : beanNames) {
// 为每个beanName,注册一个空的BeanDefinition，方法2
registerDubboConfigBean(beanName, configClass, registry);
// 为每个bean注册一个DubboConfigBindingBeanPostProcessor的Bean后置处理器，方法3
//这里存在的问题就是对应每一种配置都会产生对应的BeanPostProcessor，最多好像也就是10种左右
//但其实一个就可以做的任务，拓展成多个貌似不太合理，结合处理逻辑都是同一套就很尴尬
registerDubboConfigBindingBeanPostProcessor(prefix, beanName, multiple, registry);
}
// 注册一个NamePropertyDefaultValueDubboConfigBeanCustomizer的bean
registerDubboConfigBeanCustomizers(registry);
}
//方法2，为对应的配置生成一个beanDefinition，并注入到容器
private void registerDubboConfigBean(String beanName, Class<? extends AbstractConfig> configClass,BeanDefinitionRegistry registry) {
BeanDefinitionBuilder builder = rootBeanDefinition(configClass);
AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
registry.registerBeanDefinition(beanName, beanDefinition); // ApplicatinoConfig对象
if (log.isInfoEnabled()) {
log.info("...); //日志记录
}
}
//方法3
private void registerDubboConfigBindingBeanPostProcessor(String prefix, String beanName, boolean multiple,BeanDefinitionRegistry registry) {
// 注册一个DubboConfigBindingBeanPostProcessor的Bean
// 每个XxConfig的Bean对应一个DubboConfigBindingBeanPostProcessor的Bean
// 比如，一个ApplicationConfig对应一个DubboConfigBindingBeanPostProcessor，
// 一个ProtocolConfig也会对应一个DubboConfigBindingBeanPostProcessor
// 在构造DubboConfigBindingBeanPostProcessor的时候会指定构造方法的值，这样就可以区别开来了
Class<?> processorClass = DubboConfigBindingBeanPostProcessor.class;
BeanDefinitionBuilder builder = rootBeanDefinition(processorClass);
// 真实的前缀，比如dubbo.registries.r2
String actualPrefix = multiple ? normalizePrefix(prefix) + beanName : prefix;
// 添加两个构造方法参数值，所以会调用DubboConfigBindingBeanPostProcessor的两个参数的构造方法
builder.addConstructorArgValue(actualPrefix).addConstructorArgValue(beanName);
AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
registerWithGeneratedName(beanDefinition, registry);
if (log.isInfoEnabled()) {
log.info(...);
}
}
private void registerDubboConfigBeanCustomizers(BeanDefinitionRegistry registry) {
registerInfrastructureBean(registry, BEAN_NAME, NamePropertyDefaultValueDubboConfigBeanCustomizer.class);
}
@Override
public void setEnvironment(Environment environment) {
Assert.isInstanceOf(ConfigurableEnvironment.class, environment);
this.environment = (ConfigurableEnvironment) environment;
}
private Set<String> resolveMultipleBeanNames(Map<String, Object> properties) {
Set<String> beanNames = new LinkedHashSet<String>();
// 比如dubbo.protocols.p1.name=dubbo的propertyName为p1.name
for (String propertyName : properties.keySet()) {
// propertyName为p1.name
int index = propertyName.indexOf(".");
if (index > 0) {
// 截取beanName名字为p1
String beanName = propertyName.substring(0, index);
beanNames.add(beanName);
}
}
return beanNames;
}
private String resolveSingleBeanName(Map<String, Object> properties, Class<? extends AbstractConfig> configClass,BeanDefinitionRegistry registry) {
// 配置了dubbo.application.id=appl，那么appl就是beanName
String beanName = (String) properties.get("id");
// 如果beanName为null，则会进入if分支，由spring自动生成一个beanName,比如org.apache.dubbo.config.ApplicationConfig#0
if (!StringUtils.hasText(beanName)) {
BeanDefinitionBuilder builder = rootBeanDefinition(configClass);
beanName = BeanDefinitionReaderUtils.generateBeanName(builder.getRawBeanDefinition(), registry);
}
return beanName;
}
}6）单个DubboConfigBindingBeanPostProcessor的展示（删减掉部分不怎么用到的）
public class DubboConfigBindingBeanPostProcessor implements BeanPostProcessor, ApplicationContextAware, InitializingBean, BeanDefinitionRegistryPostProcessor {
private final String prefix;
private final String beanName;
private DubboConfigBinder dubboConfigBinder;
....
private List<DubboConfigBeanCustomizer> configBeanCustomizers = Collections.emptyList();
....
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
// 每个XxConfig对应一个BeanPostProcessor，所以每个DubboConfigBindingBeanPostProcessor只处理对应的beanName
if (this.beanName.equals(beanName) && bean instanceof AbstractConfig) {
AbstractConfig dubboConfig = (AbstractConfig) bean;
// 从properties文件中获取值，并设置到dubboConfig对象中
bind(prefix, dubboConfig);
// 设置dubboConfig对象的name属性，设置为beanName
customize(beanName, dubboConfig);
}
return bean;
}
private void bind(String prefix, AbstractConfig dubboConfig) {
dubboConfigBinder.bind(prefix, dubboConfig);
if (log.isInfoEnabled()) {
log.info(...);
}
}
private void customize(String beanName, AbstractConfig dubboConfig) {
for (DubboConfigBeanCustomizer customizer : configBeanCustomizers) {
customizer.customize(beanName, dubboConfig);
}
}
...
@Override
public void afterPropertiesSet() throws Exception {
initDubboConfigBinder(); // 创建DefaultDubboConfigBinder
initConfigBeanCustomizers();
}
private void initDubboConfigBinder() {
if (dubboConfigBinder == null) {
try {
// 先从Spring容器中获取DubboConfigBinder，默认获取不到
dubboConfigBinder = applicationContext.getBean(DubboConfigBinder.class);
} catch (BeansException ignored) {
if (log.isDebugEnabled()) {
log.debug("DubboConfigBinder Bean can't be found in ApplicationContext.");
}
// Use Default implementation
// 生成一个默认的
dubboConfigBinder = createDubboConfigBinder(applicationContext.getEnvironment());
}
}
dubboConfigBinder.setIgnoreUnknownFields(ignoreUnknownFields);
dubboConfigBinder.setIgnoreInvalidFields(ignoreInvalidFields);
}
private void initConfigBeanCustomizers() {
// 得到之前创建了的NamePropertyDefaultValueDubboConfigBeanCustomizer
Collection<DubboConfigBeanCustomizer> configBeanCustomizers = beansOfTypeIncludingAncestors(applicationContext, DubboConfigBeanCustomizer.class).values();
this.configBeanCustomizers = new ArrayList<>(configBeanCustomizers);
AnnotationAwareOrderComparator.sort(this.configBeanCustomizers);
}
...
}【3】注解@DubboComponentScan
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(DubboComponentScanRegistrar.class)
public @interface DubboComponentScan {
String[] value() default {};
String[] basePackages() default {};
Class<?>[] basePackageClasses() default {};
}1）导入的DubboComponentScanRegistrar类做了什么
/又是利用了实现了ImportBeanDefinitionRegistrar接口，在实例化该类会调用其registerBeanDefinitions方法；
public class DubboComponentScanRegistrar implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
//执行DubboComponentScanRegistrar
// 拿到DubboComponentScan注解所定义的包路径，扫描该package下的类，识别这些类上
Set<String> packagesToScan = getPackagesToScan(importingClassMetadata);
// 注册ServiceAnnotationBeanPostProcessor一个Bean
// 实现了BeanDefinitionRegistryPostProcessor接口，所以在Spring启动时会调用postProcessBeanDefinitionRegistry方法
// 该方法会进行扫描，扫描@Service注解了的类，然后生成BeanDefinition（会生成两个，一个普通的bean，一个ServiceBean），后续的Spring周期中会生成Bean
// 在ServiceBean中会监听ContextRefreshedEvent事件，一旦Spring启动完后，就会进行服务导出
registerServiceAnnotationBeanPostProcessor(packagesToScan, registry);
// 注册ReferenceAnnotationBeanPostProcessor
// 实现了AnnotationInjectedBeanPostProcessor接口，继而实现了InstantiationAwareBeanPostProcessorAdapter接口
// 所以Spring在启动时，在对属性进行注入时会调用AnnotationInjectedBeanPostProcessor接口中的postProcessPropertyValues方法
// 在这个过程中会按照@Refrence注解的信息去生成一个RefrenceBean对象
registerReferenceAnnotationBeanPostProcessor(registry);
}
//核心方法1，注册一个对@Service注解处理的 BeanDefinitionRegistryPostProcessor
private void registerServiceAnnotationBeanPostProcessor(Set<String> packagesToScan, BeanDefinitionRegistry registry) {
// 生成一个RootBeanDefinition，对应的beanClass为ServiceAnnotationBeanPostProcessor.class
BeanDefinitionBuilder builder = rootBeanDefinition(ServiceAnnotationBeanPostProcessor.class);
// 将包路径作为在构造ServiceAnnotationBeanPostProcessor时调用构造方法时的传入参数
builder.addConstructorArgValue(packagesToScan);
builder.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
BeanDefinitionReaderUtils.registerWithGeneratedName(beanDefinition, registry);
}
//核心方法2，注册一个对属性赋值处理的AnnotationInjectedBeanPostProcessor且带有ApplicationListener事件监听功能
private void registerReferenceAnnotationBeanPostProcessor(BeanDefinitionRegistry registry) {
// Register @Reference Annotation Bean Processor
// 注册一个ReferenceAnnotationBeanPostProcessor做为bean，ReferenceAnnotationBeanPostProcessor是一个BeanPostProcessor
BeanRegistrar.registerInfrastructureBean(registry,ReferenceAnnotationBeanPostProcessor.BEAN_NAME, ReferenceAnnotationBeanPostProcessor.class);
}
private Set<String> getPackagesToScan(AnnotationMetadata metadata) {
AnnotationAttributes attributes = AnnotationAttributes.fromMap(
metadata.getAnnotationAttributes(DubboComponentScan.class.getName()));
String[] basePackages = attributes.getStringArray("basePackages");
Class<?>[] basePackageClasses = attributes.getClassArray("basePackageClasses");
String[] value = attributes.getStringArray("value");
// Appends value array attributes
Set<String> packagesToScan = new LinkedHashSet<String>(Arrays.asList(value));
packagesToScan.addAll(Arrays.asList(basePackages));
for (Class<?> basePackageClass : basePackageClasses) {
packagesToScan.add(ClassUtils.getPackageName(basePackageClass));
}
if (packagesToScan.isEmpty()) {
return Collections.singleton(ClassUtils.getPackageName(metadata.getClassName()));
}
return packagesToScan;
}
}【4】扫描@Service注解，并且进行处理
汇总说明：实际上便是通过处理器扫描@Service注解的类，生成两个Bean【类对应的普通Bean，与Dubbo中要用到的ServiceBean】
其中ServiceBean，是先根据注解上的信息填充对应的属性，后采用环境变量中获取配置的属性，来完成属性填充。
public class ServiceAnnotationBeanPostProcessor implements BeanDefinitionRegistryPostProcessor, EnvironmentAware,ResourceLoaderAware, BeanClassLoaderAware {
...
//核心方法1
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
Set<String> resolvedPackagesToScan = resolvePackagesToScan(packagesToScan);
if (!CollectionUtils.isEmpty(resolvedPackagesToScan)) {
// 扫描包，进行Bean注册，核心方法2调用
registerServiceBeans(resolvedPackagesToScan, registry);
} else {
if (logger.isWarnEnabled()) {
logger.warn("packagesToScan is empty , ServiceBean registry will be ignored!");
}
}
}
//核心方法2
private void registerServiceBeans(Set<String> packagesToScan, BeanDefinitionRegistry registry) {
DubboClassPathBeanDefinitionScanner scanner = new DubboClassPathBeanDefinitionScanner(registry, environment, resourceLoader);
BeanNameGenerator beanNameGenerator = resolveBeanNameGenerator(registry);
scanner.setBeanNameGenerator(beanNameGenerator);
// 扫描被Service注解标注的类
scanner.addIncludeFilter(new AnnotationTypeFilter(Service.class));
scanner.addIncludeFilter(new AnnotationTypeFilter(com.alibaba.dubbo.config.annotation.Service.class));
for (String packageToScan : packagesToScan) {
// Registers @Service Bean first
// 扫描Dubbo自定义的@Service注解
scanner.scan(packageToScan);
// 查找被@Service注解的类的BeanDefinition（无论这个类有没有被@ComponentScan注解标注了）
Set<BeanDefinitionHolder> beanDefinitionHolders = findServiceBeanDefinitionHolders(scanner, packageToScan, registry, beanNameGenerator);
if (!CollectionUtils.isEmpty(beanDefinitionHolders)) {
// 扫描到BeanDefinition开始处理它，核心方法3的调用
for (BeanDefinitionHolder beanDefinitionHolder : beanDefinitionHolders) {
registerServiceBean(beanDefinitionHolder, registry, scanner);
}
if (logger.isInfoEnabled()) { logger.info(b...); }
} else {
if (logger.isWarnEnabled()) { logger.warn(...); }
}
}
}
//核心方法3
private void registerServiceBean(BeanDefinitionHolder beanDefinitionHolder, BeanDefinitionRegistry registry, DubboClassPathBeanDefinitionScanner scanner) {
// 处理扫描到的每一个BeanDefinition
// 1. 得到@Service注解上所配置的参数
// 2. 根据每一个BeanDefinition会再额外的生成一个ServiceBean
// 3. 对于每一个被@Service注解的类（服务的实现类），会生成两个Bean，一个服务实现类对应的Bean（普通Bean，和@Component一样），一个ServiceBean（Dubbo中要用到的Bean，因为在ServiceBean中包括了很的Config）
// 具体的服务实现类
Class<?> beanClass = resolveClass(beanDefinitionHolder);
// @Service可以对服务进行各种配置
Annotation service = findServiceAnnotation(beanClass);
AnnotationAttributes serviceAnnotationAttributes = getAnnotationAttributes(service, false, false);
// 服务实现类对应的接口
Class<?> interfaceClass = resolveServiceInterfaceClass(serviceAnnotationAttributes, beanClass);
// 服务实现类对应的bean的名字，比如：demoServiceImpl
String annotatedServiceBeanName = beanDefinitionHolder.getBeanName();
// 生成一个ServiceBean，核心方法4的调用
AbstractBeanDefinition serviceBeanDefinition = buildServiceBeanDefinition(service, serviceAnnotationAttributes, interfaceClass, annotatedServiceBeanName);
// ServiceBean Bean name ServiceBean表示服务，我们要使用一个服务应该拿ServiceBean
String beanName = generateServiceBeanName(serviceAnnotationAttributes, interfaceClass);
if (scanner.checkCandidate(beanName, serviceBeanDefinition)) { // check duplicated candidate bean
// 把ServiceBean注册进去，对应的beanName为ServiceBean:org.apache.dubbo.demo.DemoService
registry.registerBeanDefinition(beanName, serviceBeanDefinition);
if (logger.isInfoEnabled()) { logger.info(..); }
} else {
if (logger.isWarnEnabled()) { logger.warn(...); }
}
}
...
//核心方法4
private AbstractBeanDefinition buildServiceBeanDefinition(Annotation serviceAnnotation,AnnotationAttributes serviceAnnotationAttributes,Class<?> interfaceClass,String annotatedServiceBeanName) {
// 生成一个ServiceBean对应的BeanDefinition
BeanDefinitionBuilder builder = rootBeanDefinition(ServiceBean.class);
AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
MutablePropertyValues propertyValues = beanDefinition.getPropertyValues();
String[] ignoreAttributeNames = of("provider", "monitor", "application", "module", "registry", "protocol",
"interface", "interfaceName", "parameters");
// 把serviceAnnotation中的参数值赋值给ServiceBean的属性
// 如：@Service(test = "test")
propertyValues.addPropertyValues(new AnnotationPropertyValuesAdapter(serviceAnnotation, environment, ignoreAttributeNames));
// References "ref" property to annotated-@Service Bean
// 如：@Service(protocol = "P1")，这种就是要根据对应的值找到对应的P1的config对象里面的值
// ref属性赋值为另外一个bean, 对应的就是被@Service注解的服务实现类对应的bean
addPropertyReference(builder, "ref", annotatedServiceBeanName);
// Set interface
builder.addPropertyValue("interface", interfaceClass.getName());
// Convert parameters into map
builder.addPropertyValue("parameters", convertParameters(serviceAnnotationAttributes.getStringArray("parameters")));
// 配置了methods属性，则给ServiceBean对应的methods属性赋值
// Add methods parameters
List<MethodConfig> methodConfigs = convertMethodConfigs(serviceAnnotationAttributes.get("methods"));
if (!methodConfigs.isEmpty()) {
builder.addPropertyValue("methods", methodConfigs);
}
/**
* Add {@link org.apache.dubbo.config.ProviderConfig} Bean reference
*/
String providerConfigBeanName = serviceAnnotationAttributes.getString("provider");
if (StringUtils.hasText(providerConfigBeanName)) {
addPropertyReference(builder, "provider", providerConfigBeanName);
}
/**
* Add {@link org.apache.dubbo.config.MonitorConfig} Bean reference
*/
String monitorConfigBeanName = serviceAnnotationAttributes.getString("monitor");
if (StringUtils.hasText(monitorConfigBeanName)) {
addPropertyReference(builder, "monitor", monitorConfigBeanName);
}
/**
* Add {@link org.apache.dubbo.config.ApplicationConfig} Bean reference
*/
String applicationConfigBeanName = serviceAnnotationAttributes.getString("application");
if (StringUtils.hasText(applicationConfigBeanName)) {
addPropertyReference(builder, "application", applicationConfigBeanName);
}
/**
* Add {@link org.apache.dubbo.config.ModuleConfig} Bean reference
*/
String moduleConfigBeanName = serviceAnnotationAttributes.getString("module");
if (StringUtils.hasText(moduleConfigBeanName)) {
addPropertyReference(builder, "module", moduleConfigBeanName);
}
/**
* Add {@link org.apache.dubbo.config.RegistryConfig} Bean reference
* 获取注解上配置的注册中心的beanName
*/
String[] registryConfigBeanNames = serviceAnnotationAttributes.getStringArray("registry");
List<RuntimeBeanReference> registryRuntimeBeanReferences = toRuntimeBeanReferences(registryConfigBeanNames);
if (!registryRuntimeBeanReferences.isEmpty()) {
builder.addPropertyValue("registries", registryRuntimeBeanReferences);
}
/**
* Add {@link org.apache.dubbo.config.ProtocolConfig} Bean reference
*/
String[] protocolConfigBeanNames = serviceAnnotationAttributes.getStringArray("protocol");
List<RuntimeBeanReference> protocolRuntimeBeanReferences = toRuntimeBeanReferences(protocolConfigBeanNames);
if (!protocolRuntimeBeanReferences.isEmpty()) {
builder.addPropertyValue("protocols", protocolRuntimeBeanReferences);
}
return builder.getBeanDefinition();
}
....
}【5】扫描@Reference注解，并且进行处理
1）ReferenceAnnotationBeanPostProcessor类会被调用是基于继承关系
//class ReferenceAnnotationBeanPostProcessor extends AnnotationInjectedBeanPostProcessor
//abstract class AnnotationInjectedBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter
//InstantiationAwareBeanPostProcessorAdapter类便是属性注入时候会调用的
//调用AnnotationInjectedBeanPostProcessor抽象类的postProcessPropertyValues方法
@Override
public PropertyValues postProcessPropertyValues(
PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeanCreationException {
// 寻找需要注入的属性（被@Reference标注的Field）
InjectionMetadata metadata = findInjectionMetadata(beanName, bean.getClass(), pvs);
try {
metadata.inject(bean, beanName, pvs);
} catch (BeanCreationException ex) {
throw ex;
} catch (Throwable ex) {
throw new BeanCreationException(beanName, "Injection of @" + getAnnotationType().getSimpleName()
+ " dependencies is failed", ex);
}
return pvs;
}
//最终走回到ReferenceAnnotationBeanPostProcessor类的doGetInjectedBean方法2）ReferenceAnnotationBeanPostProcessor中的方法
public class ReferenceAnnotationBeanPostProcessor extends AnnotationInjectedBeanPostProcessor implements ApplicationContextAware, ApplicationListener {
...
// 该方法得到的对象会赋值给@ReferenceBean注解的属性
@Override
protected Object doGetInjectedBean(AnnotationAttributes attributes, Object bean, String beanName, Class<?> injectedType,InjectionMetadata.InjectedElement injectedElement) throws Exception {
// 得到引入服务的beanName
// attributes里存的是@Reference注解中的所配置的属性与值
// injectedType表示引入的是哪个服务接口
// referencedBeanName的值为 ServiceBean:org.apache.dubbo.demo.DemoService 表示得到该服务Bean的beanName
// referencedBeanName表示 我现在要引用的这个服务，它导出时对应的ServiceBean的beanName是什么，可以用来判断现在我引用的这个服务是不是我自己导出的
String referencedBeanName = buildReferencedBeanName(attributes, injectedType);
// @Reference(methods=[Lorg.apache.dubbo.config.annotation.Method;@39b43d60) org.apache.dubbo.demo.DemoService
// 我要生成一个RefrenceBean，对应的beanName， 根据@Reference注解来标识不同
String referenceBeanName = getReferenceBeanName(attributes, injectedType);
// 生成一个ReferenceBean对象，方法1
ReferenceBean referenceBean = buildReferenceBeanIfAbsent(referenceBeanName, attributes, injectedType);
// 把referenceBean添加到Spring容器中去，方法2
registerReferenceBean(referencedBeanName, referenceBean, attributes, injectedType);
cacheInjectedReferenceBean(referenceBean, injectedElement);
// 创建一个代理对象，Service中的属性被注入的就是这个代理对象
// 内部会调用referenceBean.get(); ，核心方法1
return getOrCreateProxy(referencedBeanName, referenceBeanName, referenceBean, injectedType);
}
//方法1
private ReferenceBean buildReferenceBeanIfAbsent(String referenceBeanName, AnnotationAttributes attributes, Class<?> referencedType) throws Exception {
ReferenceBean<?> referenceBean = referenceBeanCache.get(referenceBeanName);
if (referenceBean == null) {
// 生成了一个ReferenceBean对象，attributes是@Reference注解的参数值
ReferenceBeanBuilder beanBuilder = ReferenceBeanBuilder
.create(attributes, applicationContext)
.interfaceClass(referencedType);
referenceBean = beanBuilder.build();
referenceBeanCache.put(referenceBeanName, referenceBean);
} else if (!referencedType.isAssignableFrom(referenceBean.getInterfaceClass())) {
throw new IllegalArgumentException(...);
}
return referenceBean;
}
//方法2
private void registerReferenceBean(String referencedBeanName, ReferenceBean referenceBean, AnnotationAttributes attributes, Class<?> interfaceClass) {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
// @Reference(parameters=[Ljava.lang.String;@72ef8d15) org.apache.dubbo.demo.DemoService
// ReferenceBean的beanName，注意这个beanName，它是直接取的@Reference的全信息
// 所以，就算引用的是同一个服务，如果@Reference注解上的信息不同，那么就会生成不同的ReferenceBean
String beanName = getReferenceBeanName(attributes, interfaceClass);
// 要引入的服务就是本地提供的一个服务
if (existsServiceBean(referencedBeanName)) { // If @Service bean is local one
/**
* Get the @Service's BeanDefinition from {@link BeanFactory}
* Refer to {@link ServiceAnnotationBeanPostProcessor#buildServiceBeanDefinition}
*/
AbstractBeanDefinition beanDefinition = (AbstractBeanDefinition) beanFactory.getBeanDefinition(referencedBeanName);
RuntimeBeanReference runtimeBeanReference = (RuntimeBeanReference) beanDefinition.getPropertyValues().get("ref"); // ServiceBean --- ref
// The name of bean annotated @Service
String serviceBeanName = runtimeBeanReference.getBeanName();
// register Alias rather than a new bean name, in order to reduce duplicated beans
// 如果是本地提供的一个服务，那么就@Reference(parameters=[Ljava.lang.String;@72ef8d15) org.apache.dubbo.demo.DemoService
// 的别名是demoService，不需要是ServiceBean的名字
beanFactory.registerAlias(serviceBeanName, beanName);
} else { // Remote @Service Bean
if (!beanFactory.containsBean(beanName)) {
beanFactory.registerSingleton(beanName, referenceBean);
}
}
}
//核心方法1
//这里面其实有点绕，因为@Reference其实也相当于做了@Autowired的工作
//能在本地找到，如果不代理的话其实相当于@Autowired注入属性（不会走Dubbo的逻辑），所以包装成代理，让它也走Dubbo的逻辑
private Object getOrCreateProxy(String referencedBeanName, String referenceBeanName, ReferenceBean referenceBean, Class<?> serviceInterfaceType) {
//这个其实是判断本地有没有
if (existsServiceBean(referencedBeanName)) { // If the local @Service Bean exists, build a proxy of ReferenceBean
//进行代理，让它走Dubbo的逻辑
return newProxyInstance(getClassLoader(), new Class[]{serviceInterfaceType}, wrapInvocationHandler(referenceBeanName, referenceBean));
} else { // ReferenceBean should be initialized and get immediately
// 重点，服务引入的地方
return referenceBean.get();
}
}
...
}【6】图示：
Dubbo服务导出
【0】服务导出要做的几件事情：
1. 确定服务的参数
2. 确定服务支持的协议
3. 构造服务最终的URL
4. 将服务URL注册到注册中心去
5. 根据服务支持的不同协议，启动不同的Server，用来接收和处理请求
6. 因为Dubbo支持动态配置服务参数，所以服务导出时还需要绑定一个监听器Listener来监听服务的参数是否有修改，如果发现有修改，则需要重新进行导出【1】核心点记录
ServiceBean的两种暴露服务的方法
1.利用InitializingBean接口，调用export()方法（没有监听器的情况下才行）
2.利用监听ContextRefreshedEvent事件达到服务暴露
动态代理生成 Invoker 包装成 wrapperInvoker【2】ServiceBean是怎么进程服务导出的
//1是利用InitializingBean接口，调用export()方法【主要是调用父类的export()方法和发布ServiceBeanExportedEvent事件】
//2是利用监听ContextRefreshedEvent事件达到服务暴露
public class ServiceBean<T> extends ServiceConfig<T> implements InitializingBean, DisposableBean, ApplicationContextAware, ApplicationListener<ContextRefreshedEvent>, BeanNameAware, ApplicationEventPublisherAware {
....
@Override
public void setApplicationContext(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
// 如果某一个Service是通过Spring暴露的，
// 那么当需要获取该服务时就要从Spring容器中进行获取，
// 也就是从applicationContext中获取，所以需要把applicationContext添加到SpringExtensionFactory中去
SpringExtensionFactory.addApplicationContext(applicationContext);
// 一定要有这一步，不然ServiceBean将接收不到ContextRefreshedEvent事件
supportedApplicationListener = addApplicationListener(applicationContext, this);
}
//当接收到监听ContextRefreshedEvent事件时候
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
// 当前服务没有被导出并且没有卸载，才导出服务
if (!isExported() && !isUnexported()) {
if (logger.isInfoEnabled()) {
logger.info("The service ready on spring started. service: " + getInterface());
}
// 服务导出（服务注册）
export();
}
}
@Override
@SuppressWarnings({"unchecked", "deprecation"})
public void afterPropertiesSet() throws Exception {
// 如果@Service中没有配置provider
if (getProvider() == null) {
// 就从Spring容器中找ProviderConfig类型的Bean
Map<String, ProviderConfig> providerConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProviderConfig.class, false, false);
if (providerConfigMap != null && providerConfigMap.size() > 0) {
// 从Spring容器中找ProtocolConfig类型的Bean
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
// 如果存在ProtocolConfig存在，并且存在多个ProviderConfig
if (CollectionUtils.isEmptyMap(protocolConfigMap) && providerConfigMap.size() > 1) { // backward compatibility
// 如果找到多个，取第一个default等于true的ProviderConfig
List<ProviderConfig> providerConfigs = new ArrayList<ProviderConfig>();
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() != null && config.isDefault()) {
providerConfigs.add(config);
}
}
if (!providerConfigs.isEmpty()) {
setProviders(providerConfigs);
}
} else {
ProviderConfig providerConfig = null;
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() == null || config.isDefault()) {
if (providerConfig != null) {
throw new IllegalStateException(...);
}
providerConfig = config;
}
}
if (providerConfig != null) {
setProvider(providerConfig);
}
}
}
}
if (getApplication() == null && (getProvider() == null || getProvider().getApplication() == null)) {
Map<String, ApplicationConfig> applicationConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ApplicationConfig.class, false, false);
if (applicationConfigMap != null && applicationConfigMap.size() > 0) {
ApplicationConfig applicationConfig = null;
for (ApplicationConfig config : applicationConfigMap.values()) {
if (applicationConfig != null) {
throw new IllegalStateException(...);
}
applicationConfig = config;
}
if (applicationConfig != null) {
setApplication(applicationConfig);
}
}
}
if (getModule() == null && (getProvider() == null || getProvider().getModule() == null)) {
Map<String, ModuleConfig> moduleConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ModuleConfig.class, false, false);
if (moduleConfigMap != null && moduleConfigMap.size() > 0) {
ModuleConfig moduleConfig = null;
for (ModuleConfig config : moduleConfigMap.values()) {
if (config.isDefault() == null || config.isDefault()) {
if (moduleConfig != null) {
throw new IllegalStateException(...);
}
moduleConfig = config;
}
}
if (moduleConfig != null) {
setModule(moduleConfig);
}
}
}
// registryIds代码能看到，但是没找到在哪里能配置
if (StringUtils.isEmpty(getRegistryIds())) {
if (getApplication() != null && StringUtils.isNotEmpty(getApplication().getRegistryIds())) {
setRegistryIds(getApplication().getRegistryIds());
}
if (getProvider() != null && StringUtils.isNotEmpty(getProvider().getRegistryIds())) {
setRegistryIds(getProvider().getRegistryIds());
}
}
if ((CollectionUtils.isEmpty(getRegistries())) && (getProvider() == null || CollectionUtils.isEmpty(getProvider().getRegistries())) && (getApplication() == null || CollectionUtils.isEmpty(getApplication().getRegistries()))) {
Map<String, RegistryConfig> registryConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, RegistryConfig.class, false, false);
if (CollectionUtils.isNotEmptyMap(registryConfigMap)) {
List<RegistryConfig> registryConfigs = new ArrayList<>();
if (StringUtils.isNotEmpty(registryIds)) {
Arrays.stream(COMMA_SPLIT_PATTERN.split(registryIds)).forEach(id -> {
if (registryConfigMap.containsKey(id)) {
registryConfigs.add(registryConfigMap.get(id));
}
});
}
if (registryConfigs.isEmpty()) {
for (RegistryConfig config : registryConfigMap.values()) {
if (StringUtils.isEmpty(registryIds) && (config.isDefault() == null || config.isDefault().booleanValue())) {
registryConfigs.add(config);
}
}
}
if (!registryConfigs.isEmpty()) {
super.setRegistries(registryConfigs);
}
}
}
if (getMetadataReportConfig() == null) {
Map<String, MetadataReportConfig> metadataReportConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MetadataReportConfig.class, false, false);
if (metadataReportConfigMap != null && metadataReportConfigMap.size() == 1) {
super.setMetadataReportConfig(metadataReportConfigMap.values().iterator().next());
} else if (metadataReportConfigMap != null && metadataReportConfigMap.size() > 1) {
throw new IllegalStateException("Multiple MetadataReport configs: " + metadataReportConfigMap);
}
}
if (getConfigCenter() == null) {
Map<String, ConfigCenterConfig> configenterMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ConfigCenterConfig.class, false, false);
if (configenterMap != null && configenterMap.size() == 1) {
super.setConfigCenter(configenterMap.values().iterator().next());
} else if (configenterMap != null && configenterMap.size() > 1) {
throw new IllegalStateException("Multiple ConfigCenter found:" + configenterMap);
}
}
if (getMonitor() == null
&& (getProvider() == null || getProvider().getMonitor() == null)
&& (getApplication() == null || getApplication().getMonitor() == null)) {
Map<String, MonitorConfig> monitorConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MonitorConfig.class, false, false);
if (monitorConfigMap != null && monitorConfigMap.size() > 0) {
MonitorConfig monitorConfig = null;
for (MonitorConfig config : monitorConfigMap.values()) {
if (config.isDefault() == null || config.isDefault()) {
if (monitorConfig != null) {
throw new IllegalStateException("Duplicate monitor configs: " + monitorConfig + " and " + config);
}
monitorConfig = config;
}
}
if (monitorConfig != null) {
setMonitor(monitorConfig);
}
}
}
if (getMetrics() == null) {
Map<String, MetricsConfig> metricsConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, MetricsConfig.class, false, false);
if (metricsConfigMap != null && metricsConfigMap.size() > 0) {
MetricsConfig metricsConfig = null;
for (MetricsConfig config : metricsConfigMap.values()) {
if (metricsConfig != null) {
throw new IllegalStateException("Duplicate metrics configs: " + metricsConfig + " and " + config);
}
metricsConfig = config;
}
if (metricsConfig != null) {
setMetrics(metricsConfig);
}
}
}
// protocolIds也没看到在哪里配置
if (StringUtils.isEmpty(getProtocolIds())) {
if (getProvider() != null && StringUtils.isNotEmpty(getProvider().getProtocolIds())) {
setProtocolIds(getProvider().getProtocolIds());
}
}
if (CollectionUtils.isEmpty(getProtocols())
&& (getProvider() == null || CollectionUtils.isEmpty(getProvider().getProtocols()))) {
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
if (protocolConfigMap != null && protocolConfigMap.size() > 0) {
List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
if (StringUtils.isNotEmpty(getProtocolIds())) {
Arrays.stream(COMMA_SPLIT_PATTERN.split(getProtocolIds()))
.forEach(id -> {
if (protocolConfigMap.containsKey(id)) {
protocolConfigs.add(protocolConfigMap.get(id));
}
});
}
if (protocolConfigs.isEmpty()) {
for (ProtocolConfig config : protocolConfigMap.values()) {
if (StringUtils.isEmpty(protocolIds)) {
protocolConfigs.add(config);
}
}
}
if (!protocolConfigs.isEmpty()) {
super.setProtocols(protocolConfigs);
}
}
}
if (StringUtils.isEmpty(getPath())) {
if (StringUtils.isNotEmpty(beanName)
&& StringUtils.isNotEmpty(getInterface())
&& beanName.startsWith(getInterface())) {
setPath(beanName);
}
}
//没有监听事件才做暴露服务
if (!supportedApplicationListener) {
export();
}
}
//服务暴露的核心方法
@Override
public void export() {
super.export();
// Publish ServiceBeanExportedEvent
publishExportEvent();
}
private void publishExportEvent() {
ServiceBeanExportedEvent exportEvent = new ServiceBeanExportedEvent(this);
applicationEventPublisher.publishEvent(exportEvent);
}
@Override
public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
this.applicationEventPublisher = applicationEventPublisher;
}
}1）ServiceConfig类#export()方法
public synchronized void export() {
//读取配置并补全（最新最全的配置），方法1
checkAndUpdateSubConfigs();
// 检查服务是否需要导出
if (!shouldExport()) {
return;
}
// 检查是否需要延迟发布
if (shouldDelay()) {
DELAY_EXPORT_EXECUTOR.schedule(this::doExport, getDelay(), TimeUnit.MILLISECONDS);
} else {
// 导出服务，方法2
doExport();
}
}2）方法1：ServiceConfig类#checkAndUpdateSubConfigs()方法
/**
* 1. ServiceConfig中的某些属性如果是空的，那么就从ProviderConfig、ModuleConfig、ApplicationConfig中获取
* 2. 从配置中心获取配置，包括应用配置和全局配置
* 3. 从配置中心获取Provider配置
* 4. 从配置中心获取Protocol配置
* 5. 如果ApplicationConfig为空，则构造一个ApplicationConfig
* 6. 从配置中心获取Registry配置
* 7. 更新ServiceConfig中的属性为优先级最高的配置
* 8. 更新MetadataReportConfig中的属性为优先级最高的配置
* 9. 检查当前服务是不是一个泛化服务
* 10.检查Stub和Local
* 11.检查Mock
*/
public void checkAndUpdateSubConfigs() {
// ServiceConfig中的某些属性如果是空的，那么就从ProviderConfig、ModuleConfig、ApplicationConfig中获取（之前生成的配置Bean）
completeCompoundConfigs();
// 方法1.1
// 从配置中心获取配置，包括应用配置和全局配置
// 把获取到的配置放入到Environment中的externalConfigurationMap和appExternalConfigurationMap中
// 并刷新所有的Config属性
startConfigCenter();
// 如果没有ProviderConfig对象，则创建一个
checkDefault();
// 如果没有单独的配置protocols，那么就从provider获取配置的协议，添加到的ServiceConfig中去
// 假如程序员在配置文件中配了一个dubbo协议，配置中心的全局配置或应用配置中也配置了一个协议，那么就会被添加到ServiceConfig中
checkProtocol();
checkApplication();
// if protocol is not injvm checkRegistry
// 如果protocol不是只有injvm协议，表示服务调用不是只在本机jvm里面调用，那就需要用到注册中心
// 如果protocol是injvm，表示本地调用
if (!isOnlyInJvm()) {
checkRegistry();
}
// 刷新ServiceConfig，方法1.2
this.refresh();
// 如果配了metadataReportConfig，那么就刷新配置
checkMetadataReport();
if (StringUtils.isEmpty(interfaceName)) {
throw new IllegalStateException("<dubbo:service interface=\"\" /> interface not allow null!");
}
// 当前服务对应的实现类是一个GenericService，表示没有特定的接口
if (ref instanceof GenericService) {
interfaceClass = GenericService.class;
if (StringUtils.isEmpty(generic)) {
generic = Boolean.TRUE.toString();
}
} else {
// 加载接口
try {
interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
.getContextClassLoader());
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
// 刷新MethodConfig，并判断MethodConfig中对应的方法在接口中是否存在
checkInterfaceAndMethods(interfaceClass, methods);
// 实现类是不是该接口类型
checkRef();
generic = Boolean.FALSE.toString();
}
// local和stub一样，不建议使用了
if (local != null) {
// 如果本地存根为true，则存根类为interfaceName + "Local"
if (Boolean.TRUE.toString().equals(local)) {
local = interfaceName + "Local";
}
// 加载本地存根类
Class<?> localClass;
try {
localClass = ClassUtils.forNameWithThreadContextClassLoader(local);
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
if (!interfaceClass.isAssignableFrom(localClass)) {
throw new IllegalStateException("The local implementation class " + localClass.getName() + " not implement interface " + interfaceName);
}
}
// 本地存根
if (stub != null) {
// 如果本地存根为true，则存根类为interfaceName + "Stub"
if (Boolean.TRUE.toString().equals(stub)) {
stub = interfaceName + "Stub";
}
Class<?> stubClass;
try {
stubClass = ClassUtils.forNameWithThreadContextClassLoader(stub);
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
if (!interfaceClass.isAssignableFrom(stubClass)) {
throw new IllegalStateException("The stub implementation class " + stubClass.getName() + " not implement interface " + interfaceName);
}
}
// 检查local和stub
checkStubAndLocal(interfaceClass);
// 检查mock
checkMock(interfaceClass);
}3）方法1.1，AbstractInterfaceConfig类#startConfigCenter()方法
void startConfigCenter() {
if (configCenter == null) {
ConfigManager.getInstance().getConfigCenter().ifPresent(cc -> this.configCenter = cc);
}
// 如果配置了ConfigCenter
if (this.configCenter != null) {
// 从其他位置获取配置中心的相关属性信息，比如配置中心地址
// TODO there may have duplicate refresh
this.configCenter.refresh();
// 属性更新后，从远程配置中心获取数据(应用配置，全局配置)
prepareEnvironment();
}
// 从配置中心取到配置数据后，刷新所有的XxConfig中的属性
ConfigManager.getInstance().refreshAll();
}
private void prepareEnvironment() {
if (configCenter.isValid()) {
if (!configCenter.checkOrUpdateInited()) {
return;
}
// 动态配置中心，管理台上的配置中心
DynamicConfiguration dynamicConfiguration = getDynamicConfiguration(configCenter.toUrl());
// 如果是zookeeper，获取的就是/dubbo/config/dubbo/dubbo.properties节点中的内容
String configContent = dynamicConfiguration.getProperties(configCenter.getConfigFile(), configCenter.getGroup());
String appGroup = application != null ? application.getName() : null;
String appConfigContent = null;
if (StringUtils.isNotEmpty(appGroup)) {
// 获取的就是/dubbo/config/dubbo-demo-consumer-application/dubbo.properties节点中的内容
// 这里有bug
appConfigContent = dynamicConfiguration.getProperties (StringUtils.isNotEmpty(configCenter.getAppConfigFile()) ? configCenter.getAppConfigFile() : configCenter.getConfigFile(), appGroup );
}
try {
Environment.getInstance().setConfigCenterFirst(configCenter.isHighestPriority());
Environment.getInstance().updateExternalConfigurationMap(parseProperties(configContent));
Environment.getInstance().updateAppExternalConfigurationMap(parseProperties(appConfigContent));
} catch (IOException e) {
throw new IllegalStateException(...);
}
}
}4）方法1.2，AbstractInterfaceConfig类#refresh()方法
// 刷新XxConfig
// 一个XxConfig对象的属性可能是有值的，也可能是没有值的，这时需要从其他位置获取属性值,来进行属性的覆盖
// 覆盖的优先级，从大到小为系统变量->配置中心应用配置->配置中心全局配置->注解或xml中定义->dubbo.properties文件
// 以ServiceConfig为例，ServiceConfig中包括很多属性，比如timeout
// 但是在定义一个Service时，如果在注解上没有配置timeout，那么就会其他地方获取timeout的配置
// 比如可以从系统变量->配置中心应用配置->配置中心全局配置->注解或xml中定义->dubbo.properties文件
// refresh是刷新，将当前ServiceConfig上的set方法所对应的属性更新为优先级最高的值
public void refresh() {
try {
CompositeConfiguration compositeConfiguration = Environment.getInstance().getConfiguration(getPrefix(), getId());
// 表示XxConfig对象本身- AbstractConfig
Configuration config = new ConfigConfigurationAdapter(this);
//设置顺序，
if (Environment.getInstance().isConfigCenterFirst()) {
// The sequence would be: SystemConfiguration -> AppExternalConfiguration -> ExternalConfiguration -> AbstractConfig -> PropertiesConfiguration
compositeConfiguration.addConfiguration(4, config);
} else {
// The sequence would be: SystemConfiguration -> AbstractConfig -> AppExternalConfiguration -> ExternalConfiguration -> PropertiesConfiguration
compositeConfiguration.addConfiguration(2, config);
}
// loop methods, get override value and set the new value back to method
//
Method[] methods = getClass().getMethods();
for (Method method : methods) {
// 是不是setXX()方法
if (MethodUtils.isSetter(method)) {
// 获取xx配置项的value
String value = StringUtils.trim(compositeConfiguration.getString(extractPropertyName(getClass(), method)));
// isTypeMatch() is called to avoid duplicate and incorrect update, for example, we have two 'setGeneric' methods in ReferenceConfig.
if (StringUtils.isNotEmpty(value) && ClassUtils.isTypeMatch(method.getParameterTypes()[0], value)) {
method.invoke(this, ClassUtils.convertPrimitive(method.getParameterTypes()[0], value));
}
// 是不是setParameters()方法
} else if (isParametersSetter(method)) {
// 获取parameter配置项的value
String value = StringUtils.trim(compositeConfiguration.getString(extractPropertyName(getClass(), method)));
if (StringUtils.isNotEmpty(value)) {
Map<String, String> map = invokeGetParameters(getClass(), this);
map = map == null ? new HashMap<>() : map;
map.putAll(convert(StringUtils.parseParameters(value), ""));
invokeSetParameters(getClass(), this, map);
}
}
}
} catch (Exception e) {
logger.error("Failed to override ", e);
}
}
public CompositeConfiguration getConfiguration(String prefix, String id) {
CompositeConfiguration compositeConfiguration = new CompositeConfiguration();
// Config center has the highest priority
// JVM环境变量
compositeConfiguration.addConfiguration(this.getSystemConfig(prefix, id));
// 操作系统环境变量
compositeConfiguration.addConfiguration(this.getEnvironmentConfig(prefix, id));
// 配置中心APP配置
compositeConfiguration.addConfiguration(this.getAppExternalConfig(prefix, id));
// 配置中心Global配置
compositeConfiguration.addConfiguration(this.getExternalConfig(prefix, id));
// dubbo.properties中的配置
compositeConfiguration.addConfiguration(this.getPropertiesConfig(prefix, id));
return compositeConfiguration;
}5）方法2，ServiceConfig类#doExport()方法
protected synchronized void doExport() {
// 当前服务已经被取消了，就不能再导出了
if (unexported) {
throw new IllegalStateException(...);
}
// 已经导出了，就不再导出了
if (exported) {
return;
}
exported = true;
if (StringUtils.isEmpty(path)) {
path = interfaceName;
}
doExportUrls();
}
@SuppressWarnings({"unchecked", "rawtypes"})
private void doExportUrls() {
// 得到url，注册服务也是一个服务，所以也会有对应的url，通过调用该url完成服务注册
List<URL> registryURLs = loadRegistries(true); //
// 遍历每个协议
// 一个协议一个服务
for (ProtocolConfig protocolConfig : protocols) {
// path表示服务名
// contextPath表示应用名（可配置）
// pathKey = group/contextpath/path:version
// 例子：myGroup/user/org.apache.dubbo.demo.DemoService:1.0.1
String pathKey = URL.buildKey(getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path), group, version);
// ProviderModel中存在服务提供者访问路径，实现类，接口，以及接口中的各个方法对应的ProviderMethodModel
// ProviderMethodModel表示某一个方法，方法名，所属的服务的，
ProviderModel providerModel = new ProviderModel(pathKey, ref, interfaceClass);
// ApplicationModel表示应用中有哪些服务提供者和引用了哪些服务
ApplicationModel.initProviderModel(pathKey, providerModel);
// 每种协议导出一个单独的服务,注册到各个注册中心
doExportUrlsFor1Protocol(protocolConfig, registryURLs);
}
}6）doExportUrlsFor1Protocol方法
private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
// protocolConfig表示某个协议，registryURLs表示所有的注册中心
// 如果配置的某个协议，没有配置name，那么默认为dubbo
String name = protocolConfig.getName();
if (StringUtils.isEmpty(name)) {
name = DUBBO;
}
// 这个map表示服务url的参数
Map<String, String> map = new HashMap<String, String>();
map.put(SIDE_KEY, PROVIDER_SIDE);
appendRuntimeParameters(map);
// 监控中心参数
appendParameters(map, metrics);
// 应用相关参数
appendParameters(map, application);
// 模块相关参数
appendParameters(map, module);
// 提供者相关参数
appendParameters(map, provider);
// 协议相关参数
appendParameters(map, protocolConfig);
// 服务本身相关参数
appendParameters(map, this);
// 服务中某些方法参数
if (CollectionUtils.isNotEmpty(methods)) {
for (MethodConfig method : methods) {
// 某个方法的配置参数，注意有prefix
appendParameters(map, method, method.getName());
String retryKey = method.getName() + ".retry";
// 如果某个方法配置存在xx.retry=false，则改成xx.retry=0
if (map.containsKey(retryKey)) {
String retryValue = map.remove(retryKey);
if (Boolean.FALSE.toString().equals(retryValue)) {
map.put(method.getName() + ".retries", "0");
}
}
List<ArgumentConfig> arguments = method.getArguments();
if (CollectionUtils.isNotEmpty(arguments)) {
// 遍历当前方法配置中的参数配置
for (ArgumentConfig argument : arguments) {
// 如果配置了type，则遍历当前接口的所有方法，然后找到方法名和当前方法名相等的方法，可能存在多个
// 如果配置了index,则看index对应位置的参数类型是否等于type,如果相等，则向map中存入argument对象中的参数
// 如果没有配置index，那么则遍历方法所有的参数类型，等于type则向map中存入argument对象中的参数
// 如果没有配置type,但配置了index,则把对应位置的argument放入map
// convert argument type
if (argument.getType() != null && argument.getType().length() > 0) {
Method[] methods = interfaceClass.getMethods();
// visit all methods
if (methods != null && methods.length > 0) {
for (int i = 0; i < methods.length; i++) {
String methodName = methods[i].getName();
// target the method, and get its signature
if (methodName.equals(method.getName())) {
Class<?>[] argtypes = methods[i].getParameterTypes();
// one callback in the method
if (argument.getIndex() != -1) {
if (argtypes[argument.getIndex()].getName().equals(argument.getType())) {
appendParameters(map, argument, method.getName() + "." + argument.getIndex());
} else {
throw new IllegalArgumentException(...);
}
} else {
// multiple callbacks in the method
for (int j = 0; j < argtypes.length; j++) {
Class<?> argclazz = argtypes[j];
if (argclazz.getName().equals(argument.getType())) {
appendParameters(map, argument, method.getName() + "." + j);
if (argument.getIndex() != -1 && argument.getIndex() != j) {
throw new IllegalArgumentException(...);
}
}
}
}
}
}
}
} else if (argument.getIndex() != -1) {
appendParameters(map, argument, method.getName() + "." + argument.getIndex());
} else {
throw new IllegalArgumentException(...);
}
}
}
} // end of methods for
}
if (ProtocolUtils.isGeneric(generic)) {
map.put(GENERIC_KEY, generic);
map.put(METHODS_KEY, ANY_VALUE);
} else {
String revision = Version.getVersion(interfaceClass, version);
if (revision != null && revision.length() > 0) {
map.put(REVISION_KEY, revision);
}
// 通过接口对应的Wrapper，拿到接口中所有的方法名字
String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames();
if (methods.length == 0) {
logger.warn("No method found in service interface " + interfaceClass.getName());
map.put(METHODS_KEY, ANY_VALUE);
} else {
map.put(METHODS_KEY, StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));
}
}
// Token是为了防止服务被消费者直接调用（伪造http请求）
// 主要是存于注册中心，调用时Token匹配成功即算通过（所以要求调用者是通过注册中心获取提供方的信息）
if (!ConfigUtils.isEmpty(token)) {
if (ConfigUtils.isDefault(token)) {
map.put(TOKEN_KEY, UUID.randomUUID().toString());
} else {
map.put(TOKEN_KEY, token);
}
}
// export service
// 通过该host和port访问该服务
String host = this.findConfigedHosts(protocolConfig, registryURLs, map);
Integer port = this.findConfigedPorts(protocolConfig, name, map);
// 服务url
URL url = new URL(name, host, port, getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path), map);
// url：http://192.168.40.17:80/org.apache.dubbo.demo.DemoService?anyhost=true&application=dubbo-demo-annotation-provider&bean.name=ServiceBean:org.apache.dubbo.demo.DemoService&bind.ip=192.168.40.17&bind.port=80&deprecated=false&dubbo=2.0.2&dynamic=true&generic=false&interface=org.apache.dubbo.demo.DemoService&methods=sayHello&pid=285072&release=&side=provider×tamp=1585206500409
// 可以通过ConfiguratorFactory，在服务导出时候进行统一配置
if (ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class).hasExtension(url.getProtocol())) {
url = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class).getExtension(url.getProtocol()).getConfigurator(url).configure(url);
}
String scope = url.getParameter(SCOPE_KEY); // scope可能为null，remote, local,none
// don't export when none is configured
if (!SCOPE_NONE.equalsIgnoreCase(scope)) {
// 如果scope为none,则不会进行任何的服务导出，既不会远程，也不会本地
// export to local if the config is not remote (export to remote only when config is remote)
if (!SCOPE_REMOTE.equalsIgnoreCase(scope)) {
// 如果scope不是remote,则会进行本地导出，会把当前url的protocol改为injvm，然后进行导出
exportLocal(url);
}
// export to remote if the config is not local (export to local only when config is local)
if (!SCOPE_LOCAL.equalsIgnoreCase(scope)) {
// 如果scope不是local,则会进行远程导出
if (CollectionUtils.isNotEmpty(registryURLs)) {
// 如果有注册中心，则将服务注册到注册中心
for (URL registryURL : registryURLs) {
//if protocol is only injvm ,not register
// 如果是injvm，则不需要进行注册中心注册
if (LOCAL_PROTOCOL.equalsIgnoreCase(url.getProtocol())) {
continue;
}
// 该服务是否是动态，对应zookeeper上表示是否是临时节点，对应dubbo中的功能就是静态服务
url = url.addParameterIfAbsent(DYNAMIC_KEY, registryURL.getParameter(DYNAMIC_KEY));
// 基于注册中心地址的到监控中心地址，为什么是基于注册中心地址？
URL monitorUrl = loadMonitor(registryURL);
// 把监控中心地址添加到服务url中
if (monitorUrl != null) {
url = url.addParameterAndEncoded(MONITOR_KEY, monitorUrl.toFullString());
}
// 服务的register参数，如果为true，则表示要注册到注册中心
if (logger.isInfoEnabled()) {
if (url.getParameter(REGISTER_KEY, true)) {
logger.info(...);
} else {
logger.info(...);
}
}
// For providers, this is used to enable custom proxy to generate invoker
// 服务使用的动态代理机制，如果为空则使用javassit
String proxy = url.getParameter(PROXY_KEY);
if (StringUtils.isNotEmpty(proxy)) {
registryURL = registryURL.addParameter(PROXY_KEY, proxy);
}
// 生成一个当前服务接口的代理对象
// 使用代理生成一个Invoker，Invoker表示服务提供者的代理，可以使用Invoker的invoke方法执行服务
// 对应的url为 registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-annotation-provider&dubbo=2.0.2&export=http%3A%2F%2F192.168.40.17%3A80%2Forg.apache.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Ddubbo-demo-annotation-provider%26bean.name%3DServiceBean%3Aorg.apache.dubbo.demo.DemoService%26bind.ip%3D192.168.40.17%26bind.port%3D80%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26interface%3Dorg.apache.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D19472%26release%3D%26side%3Dprovider%26timestamp%3D1585207994860&pid=19472®istry=zookeeper×tamp=1585207994828
// 这个Invoker中包括了服务的实现者、服务接口类、服务的注册地址（针对当前服务的，参数export指定了当前服务）
// 此invoker表示一个可执行的服务，调用invoker的invoke()方法即可执行服务,同时此invoker也可用来导出
Invoker<?> invoker = PROXY_FACTORY.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(EXPORT_KEY, url.toFullString()));
// DelegateProviderMetaDataInvoker也表示服务提供者，包括了Invoker和服务的配置
DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);
// 使用特定的协议来对服务进行导出，这里的协议为RegistryProtocol，导出成功后得到一个Exporter
// 1. 先使用RegistryProtocol进行服务注册
// 2. 注册完了之后，使用DubboProtocol进行导出
Exporter<?> exporter = protocol.export(wrapperInvoker);
exporters.add(exporter);
}
} else {
// 没有配置注册中心时，也会导出服务
Invoker<?> invoker = PROXY_FACTORY.getInvoker(ref, (Class) interfaceClass, url);
DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);
Exporter<?> exporter = protocol.export(wrapperInvoker);
exporters.add(exporter);
}
// 根据服务url，讲服务的元信息存入元数据中心
MetadataReportService metadataReportService = null;
if ((metadataReportService = getMetadataReportService()) != null) {
metadataReportService.publishProvider(url);
}
}
}
this.urls.add(url);
}7）protocol.export的调用
@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
// 导出服务
// registry:// ---> RegistryProtocol
// zookeeper:// ---> ZookeeperRegistry
// dubbo:// ---> DubboProtocol
// provider:// --->
// 将registry://xxx?xx=xx®istry=zookeeper 转为---> zookeeper://xxx?xx=xx
URL registryUrl = getRegistryUrl(originInvoker); // zookeeper://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-provider-application&dubbo=2.0.2&export=dubbo%3A%2F%2F192.168.40.17%3A20880%2Forg.apache.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Ddubbo-demo-provider-application%26bean.name%3DServiceBean%3Aorg.apache.dubbo.demo.DemoService%26bind.ip%3D192.168.40.17%26bind.port%3D20880%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26interface%3Dorg.apache.dubbo.demo.DemoService%26logger%3Dlog4j%26methods%3DsayHello%26pid%3D27656%26release%3D2.7.0%26side%3Dprovider%26timeout%3D3000%26timestamp%3D1590735956489&logger=log4j&pid=27656&release=2.7.0×tamp=1590735956479
// 得到服务提供者url
URL providerUrl = getProviderUrl(originInvoker); // dubbo://192.168.40.17:20880/org.apache.dubbo.demo.DemoService?anyhost=true&application=dubbo-demo-provider-application&bean.name=ServiceBean:org.apache.dubbo.demo.DemoService&bind.ip=192.168.40.17&bind.port=20880&deprecated=false&dubbo=2.0.2&dynamic=true&generic=false&interface=org.apache.dubbo.demo.DemoService&logger=log4j&methods=sayHello&pid=27656&release=2.7.0&side=provider&timeout=3000×tamp=1590735956489
// Subscribe the override data
// FIXME When the provider subscribes, it will affect the scene : a certain JVM exposes the service and call
// the same service. Because the subscribed is cached key with the name of the service, it causes the
// subscription information to cover.
// overrideSubscribeUrl是老版本的动态配置监听url，表示了需要监听的服务以及监听的类型（configurators， 这是老版本上的动态配置）
// 在服务提供者url的基础上，生成一个overrideSubscribeUrl，协议为provider://，增加参数category=configurators&check=false
final URL overrideSubscribeUrl = getSubscribedOverrideUrl(providerUrl);
// 一个overrideSubscribeUrl对应一个OverrideListener，用来监听变化事件，监听到overrideSubscribeUrl的变化后，
// OverrideListener就会根据变化进行相应处理，具体处理逻辑看OverrideListener的实现
final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
// 在这个方法里会利用providerConfigurationListener和serviceConfigurationListener去重写providerUrl
// providerConfigurationListener表示应用级别的动态配置监听器，providerConfigurationListener是RegistyProtocol的一个属性
// serviceConfigurationListener表示服务级别的动态配置监听器，serviceConfigurationListener是在每暴露一个服务时就会生成一个
// 这两个监听器都是新版本中的监听器
// 新版本监听的zk路径是：
// 服务： /dubbo/config/dubbo/org.apache.dubbo.demo.DemoService.configurators节点的内容
// 应用： /dubbo/config/dubbo/dubbo-demo-provider-application.configurators节点的内容
// 注意，要喝配置中心的路径区分开来，配置中心的路径是：
// 应用：/dubbo/config/dubbo/org.apache.dubbo.demo.DemoService/dubbo.properties节点的内容
// 全局：/dubbo/config/dubbo/dubbo.properties节点的内容
providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);
// export invoker
// 根据动态配置重写了providerUrl之后，就会调用DubboProtocol或HttpProtocol去进行导出服务了
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
// url to registry
// 得到注册中心-ZookeeperRegistry
final Registry registry = getRegistry(originInvoker);
// 得到存入到注册中心去的providerUrl,会对服务提供者url中的参数进行简化
final URL registeredProviderUrl = getRegisteredProviderUrl(providerUrl, registryUrl);
// 将当前服务提供者Invoker，以及该服务对应的注册中心地址，以及简化后的服务url存入ProviderConsumerRegTable
ProviderInvokerWrapper<T> providerInvokerWrapper = ProviderConsumerRegTable.registerProvider(originInvoker, registryUrl, registeredProviderUrl);
//to judge if we need to delay publish
//是否需要注册到注册中心
boolean register = providerUrl.getParameter(REGISTER_KEY, true);
if (register) {
// 注册服务，把简化后的服务提供者url注册到registryUrl中去
register(registryUrl, registeredProviderUrl);
providerInvokerWrapper.setReg(true);
}
// 针对老版本的动态配置，需要把overrideSubscribeListener绑定到overrideSubscribeUrl上去进行监听
// 兼容老版本的配置修改，利用overrideSubscribeListener去监听旧版本的动态配置变化
// 监听overrideSubscribeUrl provider://192.168.40.17:20880/org.apache.dubbo.demo.DemoService?anyhost=true&application=dubbo-demo-annotation-provider&bean.name=ServiceBean:org.apache.dubbo.demo.DemoService&bind.ip=192.168.40.17&bind.port=20880&category=configurators&check=false&deprecated=false&dubbo=2.0.2&dynamic=true&generic=false&interface=org.apache.dubbo.demo.DemoService&methods=sayHello&pid=416332&release=&side=provider×tamp=1585318241955
// 那么新版本的providerConfigurationListener和serviceConfigurationListener是在什么时候进行订阅的呢？在这两个类构造的时候
// Deprecated! Subscribe to override rules in 2.6.x or before.
// 老版本监听的zk路径是：/dubbo/org.apache.dubbo.demo.DemoService/configurators/override://0.0.0.0/org.apache.dubbo.demo.DemoService?category=configurators&compatible_config=true&dynamic=false&enabled=true&timeout=6000
// 监听的是路径的内容，不是节点的内容
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
exporter.setRegisterUrl(registeredProviderUrl);
exporter.setSubscribeUrl(overrideSubscribeUrl);
//Ensure that a new exporter instance is returned every time export
return new DestroyableExporter<>(exporter);
}
public void register(URL registryUrl, URL registeredProviderUrl) {
Registry registry = registryFactory.getRegistry(registryUrl);
// 调用FailbackRegistry类的方法再转到ZookeeperRegistry的register方法
registry.register(registeredProviderUrl);
}
//FailbackRegistry类（进行失败重试）
@Override
public void register(URL url) {
super.register(url);
removeFailedRegistered(url);
removeFailedUnregistered(url);
try {
// 这里才会调用ZookeeperRegistry类的方法
doRegister(url);
} catch (Exception e) {
Throwable t = e;
// If the startup detection is opened, the Exception is thrown directly.
boolean check = getUrl().getParameter(Constants.CHECK_KEY, true) && url.getParameter(Constants.CHECK_KEY, true) && !CONSUMER_PROTOCOL.equals(url.getProtocol());
boolean skipFailback = t instanceof SkipFailbackWrapperException;
if (check || skipFailback) {
if (skipFailback) {
t = t.getCause();
}
throw new IllegalStateException(...);
} else {
logger.error(...);
}
addFailedRegistered(url);
}
}
//ZookeeperRegistry的真正注册的地方
@Override
public void doRegister(URL url) {
try {
zkClient.create(toUrlPath(url), url.getParameter(DYNAMIC_KEY, true));
} catch (Throwable e) {
throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
}
}8）doLocalExport方法
@SuppressWarnings("unchecked")
private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker, URL providerUrl) {
String key = getCacheKey(originInvoker);
return (ExporterChangeableWrapper<T>) bounds.computeIfAbsent(key, s -> {
Invoker<?> invokerDelegate = new InvokerDelegate<>(originInvoker, providerUrl);
// protocol属性的值是哪来的，是在SPI中注入进来的，是一个代理类
// 这里实际利用的就是DubboProtocol或HttpProtocol去export NettyServer
// 为什么需要ExporterChangeableWrapper？方便注销已经被导出的服务
return new ExporterChangeableWrapper<>((Exporter<T>) protocol.export(invokerDelegate), originInvoker);
});
}
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
URL url = invoker.getUrl();
// export service.
String key = serviceKey(url);
// 构造一个Exporter
DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);
exporterMap.put(key, exporter);
//export an stub service for dispatching event
Boolean isStubSupportEvent = url.getParameter(STUB_EVENT_KEY, DEFAULT_STUB_EVENT);
Boolean isCallbackservice = url.getParameter(IS_CALLBACK_SERVICE, false);
if (isStubSupportEvent && !isCallbackservice) {
String stubServiceMethods = url.getParameter(STUB_EVENT_METHODS_KEY);
if (stubServiceMethods == null || stubServiceMethods.length() == 0) {
if (logger.isWarnEnabled()) {
logger.warn(...);
}
} else {
// 服务的stub方法
stubServiceMethodsMap.put(url.getServiceKey(), stubServiceMethods);
}
}
// 开启NettyServer
openServer(url);
optimizeSerialization(url);
return exporter;
}
private void openServer(URL url) {
// find server.
String key = url.getAddress(); // 获得ip地址和port， 192.168.40.17:20880
// NettyClient, NettyServer
//client can export a service which's only for server to invoke
boolean isServer = url.getParameter(IS_SERVER_KEY, true);
if (isServer) {
// 缓存Server对象
ExchangeServer server = serverMap.get(key);
// DCL，Double Check Lock
if (server == null) {
synchronized (this) {
server = serverMap.get(key);
if (server == null) {
// 创建Server，并进行缓存
serverMap.put(key, createServer(url));
}
}
} else {
// server supports reset, use together with override
// 服务重新导出时，就会走这里
server.reset(url);
}
}
}
private ExchangeServer createServer(URL url) {
url = URLBuilder.from(url)
// send readonly event when server closes, it's enabled by default
.addParameterIfAbsent(CHANNEL_READONLYEVENT_SENT_KEY, Boolean.TRUE.toString())
// enable heartbeat by default
.addParameterIfAbsent(HEARTBEAT_KEY, String.valueOf(DEFAULT_HEARTBEAT))
.addParameter(CODEC_KEY, DubboCodec.NAME)
.build();
// 协议的服务器端实现类型，比如：dubbo协议的mina,netty等，http协议的jetty,servlet等，默认为netty
String str = url.getParameter(SERVER_KEY, DEFAULT_REMOTING_SERVER);
if (str != null && str.length() > 0 && !ExtensionLoader.getExtensionLoader(Transporter.class).hasExtension(str)) {
throw new RpcException("Unsupported server type: " + str + ", url: " + url);
}
// 通过url绑定端口，和对应的请求处理器
ExchangeServer server;
try {
// requestHandler是请求处理器，类型为ExchangeHandler
// 表示从url的端口接收到请求后，requestHandler来进行处理
server = Exchangers.bind(url, requestHandler);
} catch (RemotingException e) {
throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e);
}
// 协议的客户端实现类型，比如：dubbo协议的mina,netty等
str = url.getParameter(CLIENT_KEY);
if (str != null && str.length() > 0) {
Set<String> supportedTypes = ExtensionLoader.getExtensionLoader(Transporter.class).getSupportedExtensions();
if (!supportedTypes.contains(str)) {
throw new RpcException("Unsupported client type: " + str);
}
}
return server;
}9）当数据发生改变时 OverrideListener 监听者的处理
@Override
public synchronized void notify(List<URL> urls) {
List<URL> matchedUrls = getMatchedUrls(urls, subscribeUrl.addParameter(CATEGORY_KEY, CONFIGURATORS_CATEGORY));
// No matching results
if (matchedUrls.isEmpty()) {
return;
}
// 对发生了变化的url进行过滤，只取url是override协议，或者参数category等于configurators的url
this.configurators = Configurator.toConfigurators(classifyUrls(matchedUrls, UrlUtils::isConfigurator)).orElse(configurators);
// 根据Override协议修改
doOverrideIfNecessary();
}
public synchronized void doOverrideIfNecessary() {
final Invoker<?> invoker;
if (originInvoker instanceof InvokerDelegate) {
invoker = ((InvokerDelegate<?>) originInvoker).getInvoker();
} else {
invoker = originInvoker;
}
//The origin invoker 当前服务的原始服务提供者url
URL originUrl = RegistryProtocol.this.getProviderUrl(invoker);
String key = getCacheKey(originInvoker);
ExporterChangeableWrapper<?> exporter = bounds.get(key);
if (exporter == null) {
logger.warn(new IllegalStateException("error state, exporter should not be null"));
return;
}
//The current, may have been merged many times，当前服务被导出的url
URL currentUrl = exporter.getInvoker().getUrl();
//根据configurators修改url，configurators是全量的，并不是某个新增的或删除的，所以是基于原始的url进行修改，并不是基于currentUrl
//Merged with this configuration
URL newUrl = getConfigedInvokerUrl(configurators, originUrl);
newUrl = getConfigedInvokerUrl(providerConfigurationListener.getConfigurators(), newUrl);
newUrl = getConfigedInvokerUrl(serviceConfigurationListeners.get(originUrl.getServiceKey()).getConfigurators(), newUrl);
// 修改过的url如果和目前的url不相同，则重新按newUrl导出
if (!currentUrl.equals(newUrl)) {
RegistryProtocol.this.reExport(originInvoker, newUrl);
logger.info(...);
}
}
public <T> void reExport(final Invoker<T> originInvoker, URL newInvokerUrl) {
// 根据newInvokerUrl进行导出
// update local exporter
ExporterChangeableWrapper exporter = doChangeLocalExport(originInvoker, newInvokerUrl);
// 获取准确的ProviderUrl
// update registry
URL registryUrl = getRegistryUrl(originInvoker);
// 对于一个服务提供者url，在注册到注册中心时，会先进行简化，所以如果
final URL registeredProviderUrl = getRegisteredProviderUrl(newInvokerUrl, registryUrl);
//decide if we need to re-publish
// 根据getServiceKey获取ProviderInvokerWrapper
ProviderInvokerWrapper<T> providerInvokerWrapper = ProviderConsumerRegTable.getProviderWrapper(registeredProviderUrl, originInvoker);
// 生成一个新的ProviderInvokerWrapper
ProviderInvokerWrapper<T> newProviderInvokerWrapper = ProviderConsumerRegTable.registerProvider(originInvoker, registryUrl, registeredProviderUrl);
/**
* Only if the new url going to Registry is different with the previous one should we do unregister and register.
* 如果新的服务提供者url简化后的url和这个服务之前的服务提供者url简化后的url不相等，则需要把新的简化后的服务提供者url注册到注册中心去
*/
if (providerInvokerWrapper.isReg() && !registeredProviderUrl.equals(providerInvokerWrapper.getProviderUrl())) {
unregister(registryUrl, providerInvokerWrapper.getProviderUrl());
register(registryUrl, registeredProviderUrl);
newProviderInvokerWrapper.setReg(true);
}
exporter.setRegisterUrl(registeredProviderUrl);
}
@SuppressWarnings("unchecked")
private <T> ExporterChangeableWrapper doChangeLocalExport(final Invoker<T> originInvoker, URL newInvokerUrl) {
String key = getCacheKey(originInvoker);
final ExporterChangeableWrapper<T> exporter = (ExporterChangeableWrapper<T>) bounds.get(key);
if (exporter == null) {
logger.warn(new IllegalStateException("error state, exporter should not be null"));
} else {
// 到这里才能真正明白，为什么需要InvokerDelegate
// InvokerDelegate表示一个调用者，由invoker+url构成，invoker不变，url可变
final Invoker<T> invokerDelegate = new InvokerDelegate<T>(originInvoker, newInvokerUrl);
//这次openServer会走HeaderExchangeServer的reset方法
exporter.setExporter(protocol.export(invokerDelegate));
}
return exporter;
}
//这里面存在重新导出，关闭旧的延迟任务（旧的心跳任务），开启新的心跳任务，但是Netty不会关闭，也不会重启
@Override
public void reset(URL url) {
server.reset(url);
try {
int currHeartbeat = getHeartbeat(getUrl());
int currIdleTimeout = getIdleTimeout(getUrl());
int heartbeat = getHeartbeat(url);
int idleTimeout = getIdleTimeout(url);
if (currHeartbeat != heartbeat || currIdleTimeout != idleTimeout) {
cancelCloseTask();
startIdleCheckTask(url);
}
} catch (Throwable t) {
logger.error(t.getMessage(), t);
}
}【3】汇总
服务导出的入口为ServiceBean中的export()方法，当Spring启动完之后，通过接收Spring的ContextRefreshedEvent事件来触发export()方法的执行。
一个ServiceBean对象就表示一个Dubbo服务，ServiceBean对象中的参数就表示服务的参数，比如timeout，该对象的参数值来至@Service注解中所定义的。
服务导出主要得做两件事情：
1. 根据服务的参数信息，启动对应的网络服务器（netty、tomcat、jetty等），用来接收网络请求
2. 将服务的信息注册到注册中心
但是在做这两件事情之前得先把服务的参数确定好，因为一个Dubbo服务的参数，除开可以在@Service注解中去配置，还会继承Dubbo服务所属应用（Application）上的配置，
还可以在配置中心或JVM环境变量中去配置某个服务的参数，所以首先要做的是确定好当前服务最终的（优先级最高）的参数值。
确定好服务参数之后，就根据所配置的协议启动对应的网络服务器。在启动网络服务器时，并且在网络服务器接收请求的过程中，都可以从服务参数中获取信息，比如最大连接数，线程数，socket超时时间等等。
启动完网络服务器之后，就将服务信息注册到注册中心。同时还有向注册中心注册监听器，监听Dubbo的中的动态配置信息变更。Dubbo服务引入
【0】核心点记录
生成代理对象（代理对象应该包含的功能）{
1.获取服务提供者列表
2.Mock--------MockClusterInvoker
3.路由筛选
4.负载均衡
5.集群容错------FailoverClusterInvoker
6.构造NettyClient
7.发送数据（Invocation）
}
代理对象的Invoker
MockClusterInvoker
Invoker属性塞入FailoverClusterInvoker
FailoverClusterInvoker
Invoker属性塞入DubboInvoker【1】服务要怎么引入（ReferenceConfig类#get()方法）
//服务引入的入口方法
public synchronized T get() {
//读取配置并补全（最新最全的配置）
checkAndUpdateSubConfigs();
if (destroyed) {
throw new IllegalStateException(...);
}
if (ref == null) {
// 入口
init();
}
return ref; // Invoke代理
}【2】检查并拿到最新配置（ReferenceConfig类#checkAndUpdateSubConfigs()方法）
public void checkAndUpdateSubConfigs() {
if (StringUtils.isEmpty(interfaceName)) {
throw new IllegalStateException(...);
}
// 填充ReferenceConfig对象中的属性
completeCompoundConfigs();
// 开启配置中心
startConfigCenter();
// get consumer's global configuration
checkDefault();
// 刷新ReferenceConfig对象的属性值
this.refresh();
// 设置泛化
if (getGeneric() == null && getConsumer() != null) {
setGeneric(getConsumer().getGeneric());
}
if (ProtocolUtils.isGeneric(getGeneric())) {
interfaceClass = GenericService.class;
} else {
try {
interfaceClass = Class.forName(interfaceName, true, Thread.currentThread().getContextClassLoader());
} catch (ClassNotFoundException e) {
throw new IllegalStateException(...);
}
checkInterfaceAndMethods(interfaceClass, methods);
}
resolveFile();
checkApplication();
checkMetadataReport();
}【3】初始化生成代理对象（ReferenceConfig类#init()方法）
private void init() {
if (initialized) {
return;
}
//准备参数，进行参数配置
checkStubAndLocal(interfaceClass);
checkMock(interfaceClass);
Map<String, String> map = new HashMap<String, String>();
map.put(SIDE_KEY, CONSUMER_SIDE);
appendRuntimeParameters(map);
if (!ProtocolUtils.isGeneric(getGeneric())) {
String revision = Version.getVersion(interfaceClass, version);
if (revision != null && revision.length() > 0) {
map.put(REVISION_KEY, revision);
}
String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames();
if (methods.length == 0) {
logger.warn("No method found in service interface " + interfaceClass.getName());
map.put(METHODS_KEY, ANY_VALUE);
} else {
map.put(METHODS_KEY, StringUtils.join(new HashSet<String>(Arrays.asList(methods)), COMMA_SEPARATOR));
}
}
map.put(INTERFACE_KEY, interfaceName);
appendParameters(map, metrics);
appendParameters(map, application);
appendParameters(map, module);
// remove 'default.' prefix for configs from ConsumerConfig
// appendParameters(map, consumer, Constants.DEFAULT_KEY);
appendParameters(map, consumer);
appendParameters(map, this);
Map<String, Object> attributes = null;
if (CollectionUtils.isNotEmpty(methods)) {
attributes = new HashMap<String, Object>();
for (MethodConfig methodConfig : methods) {
appendParameters(map, methodConfig, methodConfig.getName());
String retryKey = methodConfig.getName() + ".retry";
if (map.containsKey(retryKey)) {
String retryValue = map.remove(retryKey);
if ("false".equals(retryValue)) {
map.put(methodConfig.getName() + ".retries", "0");
}
}
attributes.put(methodConfig.getName(), convertMethodConfig2AsyncInfo(methodConfig));
}
}
String hostToRegistry = ConfigUtils.getSystemProperty(DUBBO_IP_TO_REGISTRY);
if (StringUtils.isEmpty(hostToRegistry)) {
hostToRegistry = NetUtils.getLocalHost();
} else if (isInvalidLocalHost(hostToRegistry)) {
throw new IllegalArgumentException(...);
}
map.put(REGISTER_IP_KEY, hostToRegistry);
//参数配置完成后去生成代理对象
ref = createProxy(map);
String serviceKey = URL.buildKey(interfaceName, group, version);
ApplicationModel.initConsumerModel(serviceKey, buildConsumerModel(serviceKey, attributes));
initialized = true;
}【4】生成代理对象（ReferenceConfig类#createProxy()方法）
@SuppressWarnings({"unchecked", "rawtypes", "deprecation"})
private T createProxy(Map<String, String> map) {
if (shouldJvmRefer(map)) {
// injvm://
URL url = new URL(LOCAL_PROTOCOL, LOCALHOST_VALUE, 0, interfaceClass.getName()).addParameters(map);
invoker = REF_PROTOCOL.refer(interfaceClass, url);
} else {
// 为什么会有urls，因为可以在@Reference的url属性中配置多个url，可以是点对点的服务地址，也可以是注册中心的地址
urls.clear(); // reference retry init will add url to urls, lead to OOM
// @Reference中指定了url属性
if (url != null && url.length() > 0) { // user specified URL, could be peer-to-peer address, or register center's address.
String[] us = SEMICOLON_SPLIT_PATTERN.split(url); // 用;号切分
if (us != null && us.length > 0) {
for (String u : us) {
URL url = URL.valueOf(u);
if (StringUtils.isEmpty(url.getPath())) {
url = url.setPath(interfaceName);
}
// 如果是注册中心地址，则在url中添加一个refer参数
if (REGISTRY_PROTOCOL.equals(url.getProtocol())) {
// map表示消费者端配置的参数
urls.add(url.addParameterAndEncoded(REFER_KEY, StringUtils.toQueryString(map)));
} else {
// 如果是服务地址
// 有可能url中配置了参数，map中表示的服务消费者消费服务时的参数，所以需要合并
urls.add(ClusterUtils.mergeUrl(url, map));
}
}
}
} else { // assemble URL from register center's configuration
// @Reference中的protocol属性表示使用哪个协议调用服务，如果不是本地调用协议injvm://，则把注册中心地址找出来
// 对于injvm://协议已经在之前的逻辑中就已经生成invoke了
// if protocols not injvm checkRegistry
if (!LOCAL_PROTOCOL.equalsIgnoreCase(getProtocol())){
checkRegistry();
// 加载注册中心地址
List<URL> us = loadRegistries(false);
if (CollectionUtils.isNotEmpty(us)) {
for (URL u : us) {
URL monitorUrl = loadMonitor(u);
if (monitorUrl != null) {
map.put(MONITOR_KEY, URL.encode(monitorUrl.toFullString()));
}
// 对于注册中心地址都添加REFER_KEY
urls.add(u.addParameterAndEncoded(REFER_KEY, StringUtils.toQueryString(map)));
}
}
if (urls.isEmpty()) {
throw new IllegalStateException(...);
}
}
}
// 如果只有一个url则直接refer得到一个invoker
if (urls.size() == 1) {
// RegistryProtocol.refer() 或者 DubboProtocol.refer()
invoker = REF_PROTOCOL.refer(interfaceClass, urls.get(0));
} else {
// 如果有多个url
// 1. 根据每个url，refer得到对应的invoker
// 2. 如果这多个urls中存在注册中心url，则把所有invoker整合为RegistryAwareClusterInvoker，该Invoker在调用时，会查看所有Invoker中是否有默认的，如果有则使用默认的Invoker，如果没有，则使用第一个Invoker
// 2. 如果这多个urls中不存在注册中心url，则把所有invoker整合为FailoverCluster
List<Invoker<?>> invokers = new ArrayList<Invoker<?>>();
URL registryURL = null; // 用来记录urls中最后一个注册中心url
for (URL url : urls) {
invokers.add(REF_PROTOCOL.refer(interfaceClass, url));
if (REGISTRY_PROTOCOL.equals(url.getProtocol())) {
registryURL = url; // use last registry url
}
}
// 如果存在注册中心地址
if (registryURL != null) { // registry url is available
// use RegistryAwareCluster only when register's CLUSTER is available
URL u = registryURL.addParameter(CLUSTER_KEY, RegistryAwareCluster.NAME);
// StaticDirectory表示静态服务目录，里面的invokers是不会变的, 生成一个RegistryAwareCluster
// The invoker wrap relation would be: RegistryAwareClusterInvoker(StaticDirectory) -> FailoverClusterInvoker(RegistryDirectory, will execute route) -> Invoker
invoker = CLUSTER.join(new StaticDirectory(u, invokers));
} else { // not a registry url, must be direct invoke.
// 如果不存在注册中心地址, 生成一个FailoverClusterInvoker
invoker = CLUSTER.join(new StaticDirectory(invokers));
}
}
}
if (shouldCheck() && !invoker.isAvailable()) {
throw new IllegalStateException(...);
}
MetadataReportService metadataReportService = null;
if ((metadataReportService = getMetadataReportService()) != null) {
URL consumerURL = new URL(CONSUMER_PROTOCOL, map.remove(REGISTER_IP_KEY), 0, map.get(INTERFACE_KEY), map);
metadataReportService.publishConsumer(consumerURL);
}
// create service proxy
return (T) PROXY_FACTORY.getProxy(invoker);
}【5】PROXY_FACTORY.getProxy等过程
//默认采用JavassistProxyFactory来产生代理对象
public class JavassistProxyFactory extends AbstractProxyFactory {
@Override
@SuppressWarnings("unchecked")
public <T> T getProxy(Invoker<T> invoker, Class<?>[] interfaces) {
return (T) Proxy.getProxy(interfaces).newInstance(new InvokerInvocationHandler(invoker));
}
@Override
public <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) {
// TODO Wrapper cannot handle this scenario correctly: the classname contains '$'
// 如果现在被代理的对象proxy本身就是一个已经被代理过的对象，那么则取代理类的Wrapper，否则取type（接口）的Wrapper
// Wrapper是针对某个类或某个接口的包装类，通过wrapper对象可以更方便的去执行某个类或某个接口的方法
final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0 ? proxy.getClass() : type);
// proxy是服务实现类
// type是服务接口
// url是一个注册中心url，但同时也记录了
return new AbstractProxyInvoker<T>(proxy, type, url) {
@Override
protected Object doInvoke(T proxy, String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Throwable {
// 执行proxy的method方法
// 执行的proxy实例的方法
// 如果没有wrapper，则要通过原生的反射技术去获取Method对象，然后执行
return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);
}
};
}
}
public class InvokerInvocationHandler implements InvocationHandler {
private static final Logger logger = LoggerFactory.getLogger(InvokerInvocationHandler.class);
private final Invoker<?> invoker;
public InvokerInvocationHandler(Invoker<?> handler) {
this.invoker = handler;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String methodName = method.getName();
Class<?>[] parameterTypes = method.getParameterTypes();
if (method.getDeclaringClass() == Object.class) {
return method.invoke(invoker, args);
}
if ("toString".equals(methodName) && parameterTypes.length == 0) {
return invoker.toString();
}
if ("hashCode".equals(methodName) && parameterTypes.length == 0) {
return invoker.hashCode();
}
if ("equals".equals(methodName) && parameterTypes.length == 1) {
return invoker.equals(args[0]);
}
// 这里的recreate方法很重要，他会调用AppResponse的recreate方法，
// 如果AppResponse对象中存在exception信息，则此方法中会throw这个异常
return invoker.invoke(new RpcInvocation(method, args)).recreate();
}
}【6】对URL的处理过程
1）从@Reference的url属性中配置多个url，然后采用字符串分割的形式拿出来，包装后塞入urls列表中
2）加载注册中心地址
protected List<URL> loadRegistries(boolean provider) {
// check && override if necessary
List<URL> registryList = new ArrayList<URL>();
if (CollectionUtils.isNotEmpty(registries)) {
for (RegistryConfig config : registries) {
String address = config.getAddress();
// 如果注册中心没有配地址，则地址为0.0.0.0
if (StringUtils.isEmpty(address)) {
address = ANYHOST_VALUE;
}
// 如果注册中心的地址不是"N/A"
if (!RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(address)) {
Map<String, String> map = new HashMap<String, String>();
// 把application中的参数放入map中，注意，map中的key是没有prefix的
appendParameters(map, application);
// 把config中的参数放入map中，注意，map中的key是没有prefix的
// config是RegistryConfig，表示注册中心
appendParameters(map, config);
// 此处path值固定为RegistryService.class.getName()，因为现在是在加载注册中心
map.put(PATH_KEY, RegistryService.class.getName());
// 把dubbo的版本信息和pid放入map中
appendRuntimeParameters(map);
// 如果map中如果没有protocol，那么默认为dubbo
if (!map.containsKey(PROTOCOL_KEY)) {
map.put(PROTOCOL_KEY, DUBBO_PROTOCOL);
}
// 构造注册中心url，地址+参数
List<URL> urls = UrlUtils.parseURLs(address, map);
for (URL url : urls) {
url = URLBuilder.from(url)
.addParameter(REGISTRY_KEY, url.getProtocol())
.setProtocol(REGISTRY_PROTOCOL)
.build();
// 到此为止，url的内容大概为：
// registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-annotation-provider&dubbo=2.0.2&pid=269936®istry=zookeeper×tamp=1584886077813
// 该url表示：使用registry协议调用org.apache.dubbo.registry.RegistryService服务
// 参数为application=dubbo-demo-annotation-provider&dubbo=2.0.2&pid=269936®istry=zookeeper×tamp=1584886077813
// 这里是服务提供者和服务消费者区别的逻辑
// 如果是服务提供者，获取register的值，如果为false，表示该服务不注册到注册中心
// 如果是服务消费者，获取subscribe的值，如果为false，表示该引入的服务不订阅注册中心中的数据
if ((provider && url.getParameter(REGISTER_KEY, true))
|| (!provider && url.getParameter(SUBSCRIBE_KEY, true))) {
registryList.add(url);
}
}
}
}
}
return registryList;
}【7】invoker的包装过程
1）前置说明
//RegistryProtocol实际上会被两个包装类包装ProtocolListenerWrapper与ProtocolFilterWrapper
//如ProtocolListenerWrapper的protocol属性存放ProtocolFilterWrapper
//ProtocolFilterWrapper的protocol属性存放RegistryProtocol
//然后是Cluster，通过接口可知默认是FailoverCluster，但实际上还会有一个包装类MockClusterWrapper
//MockClusterWrapper的cluster属性存放FailoverCluster或者RegistryAwareCluster2）先是调用REF_PROTOCOL.refer
//ProtocolListenerWrapper的处理
@Override
public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
if (REGISTRY_PROTOCOL.equals(url.getProtocol())) {
return protocol.refer(type, url);
}
return new ListenerInvokerWrapper<T>(protocol.refer(type, url),
Collections.unmodifiableList(
ExtensionLoader.getExtensionLoader(InvokerListener.class)
.getActivateExtension(url, INVOKER_LISTENER_KEY)));
}
//ProtocolFilterWrapper的处理
@Override
public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
if (REGISTRY_PROTOCOL.equals(url.getProtocol())) {
return protocol.refer(type, url);
}
return buildInvokerChain(protocol.refer(type, url), REFERENCE_FILTER_KEY, CommonConstants.CONSUMER);
}
private static <T> Invoker<T> buildInvokerChain(final Invoker<T> invoker, String key, String group) {
Invoker<T> last = invoker;
// 根据url获取filter，根据url中的parameters取key为key的value所对应的filter，但是还会匹配group
List<Filter> filters = ExtensionLoader.getExtensionLoader(Filter.class).getActivateExtension(invoker.getUrl(), key, group);
// ConsumerContextFilter--->FutureFilter--->MonitorFilter
// ConsumerContextFilter用来设置RpcContext
if (!filters.isEmpty()) {
for (int i = filters.size() - 1; i >= 0; i--) {
final Filter filter = filters.get(i);
final Invoker<T> next = last;
last = new Invoker<T>() {
@Override
public Class<T> getInterface() {
return invoker.getInterface();
}
@Override
public URL getUrl() {
return invoker.getUrl();
}
@Override
public boolean isAvailable() {
return invoker.isAvailable();
}
@Override
public Result invoke(Invocation invocation) throws RpcException {
Result asyncResult;
try {
// 得到一个异步结果
asyncResult = filter.invoke(next, invocation);
} catch (Exception e) {
// onError callback
if (filter instanceof ListenableFilter) {
Filter.Listener listener = ((ListenableFilter) filter).listener();
if (listener != null) {
listener.onError(e, invoker, invocation);
}
}
throw e;
}
return asyncResult;
}
@Override
public void destroy() {
invoker.destroy();
}
@Override
public String toString() {
return invoker.toString();
}
};
}
}
return new CallbackRegistrationInvoker<>(last, filters);
}
//RegistryProtocol的处理
public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
// 从registry://的url中获取对应的注册中心，比如zookeeper， 默认为dubbo，dubbo提供了自带的注册中心实现
// url由 registry:// 改变为---> zookeeper://
url = URLBuilder.from(url)
.setProtocol(url.getParameter(REGISTRY_KEY, DEFAULT_REGISTRY))
.removeParameter(REGISTRY_KEY)
.build();
// 拿到注册中心实现，ZookeeperRegistry
Registry registry = registryFactory.getRegistry(url);
// 下面这个代码，通过过git历史提交记录是用来解决SimpleRegistry不可用的问题
if (RegistryService.class.equals(type)) {
return proxyFactory.getInvoker((T) registry, type, url);
}
// qs表示 queryString, 表示url中的参数，表示消费者引入服务时所配置的参数
Map<String, String> qs = StringUtils.parseQueryString(url.getParameterAndDecoded(REFER_KEY));
// group="a,b" or group="*"
String group = qs.get(GROUP_KEY);
if (group != null && group.length() > 0) {
if ((COMMA_SPLIT_PATTERN.split(group)).length > 1 || "*".equals(group)) {
// group有多个值，这里的cluster为MergeableCluster
return doRefer(getMergeableCluster(), registry, type, url);
}
}
// 这里的cluster是cluster的Adaptive对象
return doRefer(cluster, registry, type, url);
}
private <T> Invoker<T> doRefer(Cluster cluster, Registry registry, Class<T> type, URL url) {
// RegistryDirectory表示动态服务目录，会和注册中心的数据保持同步
// type表示一个服务对应一个RegistryDirectory，url表示注册中心地址
// 在消费端，最核心的就是RegistryDirectory
RegistryDirectory<T> directory = new RegistryDirectory<T>(type, url);
directory.setRegistry(registry);
directory.setProtocol(protocol);
// all attributes of REFER_KEY
// 引入服务所配置的参数
Map<String, String> parameters = new HashMap<String, String>(directory.getUrl().getParameters());
// 消费者url
URL subscribeUrl = new URL(CONSUMER_PROTOCOL, parameters.remove(REGISTER_IP_KEY), 0, type.getName(), parameters);
if (!ANY_VALUE.equals(url.getServiceInterface()) && url.getParameter(REGISTER_KEY, true)) {
directory.setRegisteredConsumerUrl(getRegisteredConsumerUrl(subscribeUrl, url));
// 注册简化后的消费url
registry.register(directory.getRegisteredConsumerUrl());
}
// 构造路由链,路由链会在引入服务时按路由条件进行过滤
// 路由链是动态服务目录中的一个属性，通过路由链可以过滤某些服务提供者
directory.buildRouterChain(subscribeUrl);
// 服务目录需要订阅的几个路径
// 当前所引入的服务的消费应用目录：/dubbo/config/dubbo/dubbo-demo-consumer-application.configurators
// 当前所引入的服务的动态配置目录：/dubbo/config/dubbo/org.apache.dubbo.demo.DemoService:1.1.1:g1.configurators
// 当前所引入的服务的提供者目录：/dubbo/org.apache.dubbo.demo.DemoService/providers
// 当前所引入的服务的老版本动态配置目录：/dubbo/org.apache.dubbo.demo.DemoService/configurators
// 当前所引入的服务的老版本路由器目录：/dubbo/org.apache.dubbo.demo.DemoService/routers
directory.subscribe(subscribeUrl.addParameter(CATEGORY_KEY,
PROVIDERS_CATEGORY + "," + CONFIGURATORS_CATEGORY + "," + ROUTERS_CATEGORY));
// 利用传进来的cluster，join得到invoker,
Invoker invoker = cluster.join(directory);
ProviderConsumerRegTable.registerConsumer(invoker, url, subscribeUrl, directory);
return invoker;
}3）再是调用CLUSTER.join
//MockClusterWrapper的处理
public class MockClusterWrapper implements Cluster {
private Cluster cluster;
public MockClusterWrapper(Cluster cluster) {
this.cluster = cluster;
}
@Override
public <T> Invoker<T> join(Directory<T> directory) throws RpcException {
return new MockClusterInvoker<T>(directory,
this.cluster.join(directory));
}
}
//有注册中心，RegistryAwareCluster的处理
public class RegistryAwareCluster implements Cluster {
public final static String NAME = "registryaware";
@Override
public <T> Invoker<T> join(Directory<T> directory) throws RpcException {
return new RegistryAwareClusterInvoker<T>(directory);
}
}
//没有注册中心，FailoverCluster的处理
public class FailoverCluster implements Cluster {
public final static String NAME = "failover";
@Override
public <T> Invoker<T> join(Directory<T> directory) throws RpcException {
return new FailoverClusterInvoker<T>(directory);
}
}【8】RegistryProtocol里面的监听过程
//directory.subscribe(subscribeUrl.addParameter(CATEGORY_KEY, PROVIDERS_CATEGORY + "," + CONFIGURATORS_CATEGORY + "," + ROUTERS_CATEGORY));
//RegistryDirectory类#subscribe方法
public void subscribe(URL url) {
setConsumerUrl(url);
CONSUMER_CONFIGURATION_LISTENER.addNotifyListener(this); // 监听consumer应用
serviceConfigurationListener = new ReferenceConfigurationListener(this, url); // 监听所引入的服务的动态配置
registry.subscribe(url, this); //老版本的监听
}
//FailbackRegistry类#subscribe方法
@Override
public void subscribe(URL url, NotifyListener listener) {
super.subscribe(url, listener);
removeFailedSubscribed(url, listener);
try {
// 核心方法
doSubscribe(url, listener);
} catch (Exception e) {
Throwable t = e;
List<URL> urls = getCacheUrls(url);
if (CollectionUtils.isNotEmpty(urls)) {
notify(url, listener, urls);
logger.error(...);
} else {
// If the startup detection is opened, the Exception is thrown directly.
boolean check = getUrl().getParameter(Constants.CHECK_KEY, true) && url.getParameter(Constants.CHECK_KEY, true);
boolean skipFailback = t instanceof SkipFailbackWrapperException;
if (check || skipFailback) {
if (skipFailback) {
t = t.getCause();
}
throw new IllegalStateException("Failed to subscribe " + url + ", cause: " + t.getMessage(), t);
} else {
logger.error("Failed to subscribe " + url + ", waiting for retry, cause: " + t.getMessage(), t);
}
}
// Record a failed registration request to a failed list, retry regularly
// 添加listener，向zk添加监听器时如果报错了，那么会把这个listener添加到failedSubscribed中，并会定时重试（重新注册listener）
addFailedSubscribed(url, listener);
}
}
// 父类AbstractRegistry#subscribe方法
// 把listener添加到subscribed中，subscribed是一个map, 存的是URL:Set<NotifyListener>
@Override
public void subscribe(URL url, NotifyListener listener) {
if (url == null) {
throw new IllegalArgumentException("subscribe url == null");
}
if (listener == null) {
throw new IllegalArgumentException("subscribe listener == null");
}
if (logger.isInfoEnabled()) {
logger.info("Subscribe: " + url);
}
Set<NotifyListener> listeners = subscribed.computeIfAbsent(url, n -> new ConcurrentHashSet<>());
listeners.add(listener);
}
// 进行订阅，先看父类的subscribe方法
@Override
public void doSubscribe(final URL url, final NotifyListener listener) {
try {
if (ANY_VALUE.equals(url.getServiceInterface())) {
// 订阅所有服务
String root = toRootPath();
ConcurrentMap<NotifyListener, ChildListener> listeners = zkListeners.get(url);
if (listeners == null) {
zkListeners.putIfAbsent(url, new ConcurrentHashMap<>());
listeners = zkListeners.get(url);
}
ChildListener zkListener = listeners.get(listener);
if (zkListener == null) {
listeners.putIfAbsent(listener, (parentPath, currentChilds) -> {
for (String child : currentChilds) {
child = URL.decode(child);
if (!anyServices.contains(child)) {
anyServices.add(child);
subscribe(url.setPath(child).addParameters(INTERFACE_KEY, child,
Constants.CHECK_KEY, String.valueOf(false)), listener);
}
}
});
zkListener = listeners.get(listener);
}
zkClient.create(root, false);
List<String> services = zkClient.addChildListener(root, zkListener);
if (CollectionUtils.isNotEmpty(services)) {
for (String service : services) {
service = URL.decode(service);
anyServices.add(service);
subscribe(url.setPath(service).addParameters(INTERFACE_KEY, service,
Constants.CHECK_KEY, String.valueOf(false)), listener);
}
}
} else {
// 单独订阅某一个服务
List<URL> urls = new ArrayList<>();
// 得到真正要监听的zk上的路径,
for (String path : toCategoriesPath(url)) {
// 根据监听地址去拿listeners，如果没有则生成
ConcurrentMap<NotifyListener, ChildListener> listeners = zkListeners.get(url);
if (listeners == null) {
zkListeners.putIfAbsent(url, new ConcurrentHashMap<>());
listeners = zkListeners.get(url);
}
// 一个NotifyListener对应一个ChildListener
ChildListener zkListener = listeners.get(listener);
if (zkListener == null) {
// lambda表达式就是监听逻辑， parentPath表示父path,currentChilds表示当前拥有的child, 会调用notify方法进行实际的处理
listeners.putIfAbsent(listener, (parentPath, currentChilds) -> ZookeeperRegistry.this.notify(url, listener, toUrlsWithEmpty(url, parentPath, currentChilds)));
zkListener = listeners.get(listener);
}
// 创建zk上路径
zkClient.create(path, false);
// 添加真正跟zk相关的ChildListener,ChildListener中的逻辑就是监听到zk上数据发生了变化后会触发的逻辑
List<String> children = zkClient.addChildListener(path, zkListener);
if (children != null) {
urls.addAll(toUrlsWithEmpty(url, path, children));
}
}
// 这里的urls就是从现在所引入的服务的目录下查到的url，比如下面这个三个目录下的路径
// "/dubbo/org.apache.dubbo.demo.DemoService/providers"
// "/dubbo/org.apache.dubbo.demo.DemoService/configurators"
// "/dubbo/org.apache.dubbo.demo.DemoService/routers"
notify(url, listener, urls);
}
} catch (Throwable e) {
throw new RpcException("Failed to subscribe " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
}
}【9】监听器触发时
//RegistryDirectory类#notify方法
public synchronized void notify(List<URL> urls) {
Map<String, List<URL>> categoryUrls = urls.stream()
.filter(Objects::nonNull)
.filter(this::isValidCategory)
.filter(this::isNotCompatibleFor26x)
.collect(Collectors.groupingBy(url -> {
if (UrlUtils.isConfigurator(url)) {
return CONFIGURATORS_CATEGORY;
} else if (UrlUtils.isRoute(url)) {
return ROUTERS_CATEGORY;
} else if (UrlUtils.isProvider(url)) {
return PROVIDERS_CATEGORY;
}
return "";
}));
// 获取动态配置URL，生成configurators
List<URL> configuratorURLs = categoryUrls.getOrDefault(CONFIGURATORS_CATEGORY, Collections.emptyList());
this.configurators = Configurator.toConfigurators(configuratorURLs).orElse(this.configurators);
// 获取老版本路由URL，生成Router，并添加到路由链中
List<URL> routerURLs = categoryUrls.getOrDefault(ROUTERS_CATEGORY, Collections.emptyList());
toRouters(routerURLs).ifPresent(this::addRouters);
// 获取服务提供者URL
List<URL> providerURLs = categoryUrls.getOrDefault(PROVIDERS_CATEGORY, Collections.emptyList());
refreshOverrideAndInvoker(providerURLs);
}
private void refreshOverrideAndInvoker(List<URL> urls) {
// mock zookeeper://xxx?mock=return null
overrideDirectoryUrl();
refreshInvoker(urls);
}
// 利用动态配置重写服务目录地址
private void overrideDirectoryUrl() {
// merge override parameters
this.overrideDirectoryUrl = directoryUrl;
List<Configurator> localConfigurators = this.configurators; // local reference
doOverrideUrl(localConfigurators);
List<Configurator> localAppDynamicConfigurators = CONSUMER_CONFIGURATION_LISTENER.getConfigurators(); // local reference
doOverrideUrl(localAppDynamicConfigurators);
if (serviceConfigurationListener != null) {
List<Configurator> localDynamicConfigurators = serviceConfigurationListener.getConfigurators(); // local reference
doOverrideUrl(localDynamicConfigurators);
}
}
private void refreshInvoker(List<URL> invokerUrls) {
Assert.notNull(invokerUrls, "invokerUrls should not be null");
if (invokerUrls.size() == 1 && invokerUrls.get(0) != null && EMPTY_PROTOCOL.equals(invokerUrls.get(0).getProtocol())) {
this.forbidden = true; // Forbid to access
this.invokers = Collections.emptyList();
routerChain.setInvokers(this.invokers);
destroyAllInvokers(); // Close all invokers
} else {
this.forbidden = false; // Allow to access
Map<String, Invoker<T>> oldUrlInvokerMap = this.urlInvokerMap; // local reference
if (invokerUrls == Collections.<URL>emptyList()) {
invokerUrls = new ArrayList<>();
}
if (invokerUrls.isEmpty() && this.cachedInvokerUrls != null) {
invokerUrls.addAll(this.cachedInvokerUrls);
} else {
this.cachedInvokerUrls = new HashSet<>();
this.cachedInvokerUrls.addAll(invokerUrls);//Cached invoker urls, convenient for comparison
}
if (invokerUrls.isEmpty()) {
return;
}
// 这里会先按Protocol进行过滤，并且调用DubboProtocol.refer方法得到DubboInvoker
Map<String, Invoker<T>> newUrlInvokerMap = toInvokers(invokerUrls);// Translate url list to Invoker map
/**
* If the calculation is wrong, it is not processed.
*
* 1. The protocol configured by the client is inconsistent with the protocol of the server.
* eg: consumer protocol = dubbo, provider only has other protocol services(rest).
* 2. The registration center is not robust and pushes illegal specification data.
*
*/
if (CollectionUtils.isEmptyMap(newUrlInvokerMap)) {
logger.error(...);
return;
}
List<Invoker<T>> newInvokers = Collections.unmodifiableList(new ArrayList<>(newUrlInvokerMap.values()));
// pre-route and build cache, notice that route cache should build on original Invoker list.
// toMergeMethodInvokerMap() will wrap some invokers having different groups, those wrapped invokers not should be routed.
// 得到了所引入的服务Invoker之后，把它们设置到路由链中去，在调用时使用，并且会调用TagRouter的notify方法
routerChain.setInvokers(newInvokers);
this.invokers = multiGroup ? toMergeInvokerList(newInvokers) : newInvokers;
this.urlInvokerMap = newUrlInvokerMap;
try {
destroyUnusedInvokers(oldUrlInvokerMap, newUrlInvokerMap); // Close the unused Invoker
} catch (Exception e) {
logger.warn("destroyUnusedInvokers error. ", e);
}
}
}
private Map<String, Invoker<T>> toInvokers(List<URL> urls) {
Map<String, Invoker<T>> newUrlInvokerMap = new HashMap<>();
if (urls == null || urls.isEmpty()) {
return newUrlInvokerMap;
}
Set<String> keys = new HashSet<>();
String queryProtocols = this.queryMap.get(PROTOCOL_KEY);
// 遍历当前服务所有的服务提供者URL
for (URL providerUrl : urls) {
// If protocol is configured at the reference side, only the matching protocol is selected
if (queryProtocols != null && queryProtocols.length() > 0) {
boolean accept = false;
String[] acceptProtocols = queryProtocols.split(",");
// 当前消费者如果手动配置了Protocol，那么则进行匹配
for (String acceptProtocol : acceptProtocols) {
if (providerUrl.getProtocol().equals(acceptProtocol)) {
accept = true;
break;
}
}
if (!accept) {
continue;
}
}
if (EMPTY_PROTOCOL.equals(providerUrl.getProtocol())) {
continue;
}
// 当前Protocol是否在应用中存在对应的扩展点
if (!ExtensionLoader.getExtensionLoader(Protocol.class).hasExtension(providerUrl.getProtocol())) {
logger.error(...);
continue;
}
URL url = mergeUrl(providerUrl);
String key = url.toFullString(); // The parameter urls are sorted
if (keys.contains(key)) { // Repeated url
continue;
}
keys.add(key);
// Cache key is url that does not merge with consumer side parameters, regardless of how the consumer combines parameters, if the server url changes, then refer again
Map<String, Invoker<T>> localUrlInvokerMap = this.urlInvokerMap; // local reference
Invoker<T> invoker = localUrlInvokerMap == null ? null : localUrlInvokerMap.get(key);
// 如果当前服务提供者URL没有生产过Invoker
if (invoker == null) { // Not in the cache, refer again
try {
boolean enabled = true;
if (url.hasParameter(DISABLED_KEY)) {
enabled = !url.getParameter(DISABLED_KEY, false);
} else {
enabled = url.getParameter(ENABLED_KEY, true);
}
if (enabled) {
// 调用Protocol的refer方法得到一个Invoker
invoker = new InvokerDelegate<>(protocol.refer(serviceType, url), url, providerUrl);
}
} catch (Throwable t) {
logger.error(...);
}
if (invoker != null) { // Put new invoker in cache
newUrlInvokerMap.put(key, invoker);
}
} else {
newUrlInvokerMap.put(key, invoker);
}
}
keys.clear();
return newUrlInvokerMap;
}本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2022-10-17，如有侵权请联系 cloudcommunity@tencent.com 删除
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