前往小程序，Get更优阅读体验！
立即前往
文档建议反馈控制台
首页
学习
活动
专区
工具
TVP
最新优惠活动
文章/答案/技术大牛
发布
首页
学习
活动
专区
工具
TVP最新优惠活动
返回腾讯云官网
社区首页 >专栏 >Dubbo服务治理篇——改造低版本Dubbo，使其兼容Spring4或Spring5注解配置

Dubbo服务治理篇——改造低版本Dubbo，使其兼容Spring4或Spring5注解配置

作者头像
冰河
发布于 2020-10-29 15:28:12
1.2K0
发布于 2020-10-29 15:28:12
举报
文章被收录于专栏：冰河技术冰河技术

温馨提示：本文有点长，但是满满的干货，建议耐心看完！

特别说明：由于很多网友留言自身使用的Dubbo框架版本比较低，无法兼容Spring4或Spring5的注解配置，故本文只针对低版本Dubbo如何兼容Spring4或Spring5的注解配置给出相应的解决方案，目前，高版本Dubbo已经不存在与Spring4或Spring5的注解配置的兼容性问题。

本文分析低版本Dubbo框架的源码，以找出不兼容Spring4或Spring5的注解配置的问题所在，并通过修改Dubbo源码以使其兼容Spring4或Spring5的注解配置。最后，由于直接修改Dubbo的源码对Dubbo框架的侵入性太强，文中又给出了如何以“外挂”的形式修改Dubbo源码并使其注册到Spring环境。

自从阿里重新维护Dubbo后，一路放大招，将Dubbo推上Apache的顶级开源项目，Dubbo经过不断的维护和发展，也相继发布了N多个版本，成为分布式与微服务领域中屈指可数的服务治理框架。目前， 笔者截稿前Dubbo的最新Release版本为apache-dubbo-2.7.4.1。

Dubbo的Release版本的源码Apache下载链接地址为：https://github.com/apache/dubbo/releases。

不过，目前，也有很多公司或组织内部使用的Dubbo版本比较老旧，很多网友在公众号留言咨询笔者，低版本的Dubbo如何兼容Spring4或Spring5。这里，笔者就借此机会写一些有关Dubbo服务治理框架的文章，供读者参考。

Dubbo本身就是基于Spring环境的，但是Dubbo当年Spring才2.版本。而现如今Spring 已经发展到5。

而随着Spring Boot的大热，Java-Base方式配置Spring也变得越来越流行。

Dubbo + Boot的开发模式，也是较为常见的组合方式。

但是，当使用低版本Dubbo在高版本Spring环境中使用注解方式配置时，会因为一些代码版本的原因导致整合出现问题。

1.Dubbo原生的注解配置

Dubbo本身就是基于Spring的，而且原生就提供注解配置： 服务提供方配置：

代码语言：javascript
复制
<!-- 扫描注解包路径，多个包用逗号分隔，不填pacakge表示扫描当前ApplicationContext中所有的类 -->
<dubbo:annotation package="com.foo.bar.service" />

服务提供方注解：

代码语言：javascript
复制
import com.alibaba.dubbo.config.annotation.Service;
 
@Service(version="1.0.0")
public class FooServiceImpl implements FooService {
    // ......
}

服务消费方注解：

代码语言：javascript
复制
import com.alibaba.dubbo.config.annotation.Reference;
import org.springframework.stereotype.Component;
 
@Component
public class BarAction {
 
    @Reference(version="1.0.0")
    private FooService fooService;
 
}

服务消费方配置：

代码语言：javascript
复制
<!-- 扫描注解包路径，多个包用逗号分隔，不填pacakge表示扫描当前ApplicationContext中所有的类 -->
<dubbo:annotation package="com.foo.bar.action" />

通过官方的例子，就可以看出Dubbo使用xml配置<dubbo:annotation /> 来开启注解配置，并提供 com.alibaba.dubbo.config.annotation.Service注解进行服务注册，提供com.alibaba.dubbo.config.annotation.Reference注解进行服务注入。

2.实现机制

可以看出，内部机制都是依托于<dubbo:annotation />标签。通过源码分析，Dubbo对于Spring xml解析处理由com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler提供：

DubboNamespaceHandler.java

代码语言：javascript
复制
package com.alibaba.dubbo.config.spring.schema;
 
import org.springframework.beans.factory.xml.NamespaceHandlerSupport;
 
import com.alibaba.dubbo.common.Version;
import com.alibaba.dubbo.config.ApplicationConfig;
import com.alibaba.dubbo.config.ConsumerConfig;
import com.alibaba.dubbo.config.ModuleConfig;
import com.alibaba.dubbo.config.MonitorConfig;
import com.alibaba.dubbo.config.ProtocolConfig;
import com.alibaba.dubbo.config.ProviderConfig;
import com.alibaba.dubbo.config.RegistryConfig;
import com.alibaba.dubbo.config.spring.AnnotationBean;
import com.alibaba.dubbo.config.spring.ReferenceBean;
import com.alibaba.dubbo.config.spring.ServiceBean;
 
/**
 * DubboNamespaceHandler
 * 
 * @author william.liangf
 * @export
 */
public class DubboNamespaceHandler extends NamespaceHandlerSupport {
 
    static {
        Version.checkDuplicate(DubboNamespaceHandler.class);
    }
 
    public void init() {
        registerBeanDefinitionParser("application", new DubboBeanDefinitionParser(ApplicationConfig.class, true));
        registerBeanDefinitionParser("module", new DubboBeanDefinitionParser(ModuleConfig.class, true));
        registerBeanDefinitionParser("registry", new DubboBeanDefinitionParser(RegistryConfig.class, true));
        registerBeanDefinitionParser("monitor", new DubboBeanDefinitionParser(MonitorConfig.class, true));
        registerBeanDefinitionParser("provider", new DubboBeanDefinitionParser(ProviderConfig.class, true));
        registerBeanDefinitionParser("consumer", new DubboBeanDefinitionParser(ConsumerConfig.class, true));
        registerBeanDefinitionParser("protocol", new DubboBeanDefinitionParser(ProtocolConfig.class, true));
        registerBeanDefinitionParser("service", new DubboBeanDefinitionParser(ServiceBean.class, true));
        registerBeanDefinitionParser("reference", new DubboBeanDefinitionParser(ReferenceBean.class, false));
        registerBeanDefinitionParser("annotation", new DubboBeanDefinitionParser(AnnotationBean.class, true));
    }
 
}

通过上面的代码可以很直观的发现，<dubbo:annotation />标签实际是由com.alibaba.dubbo.config.spring.schema.DubboBeanDefinitionParser解析：

DubboBeanDefinitionParser.java

代码语言：javascript
复制
/**
 * AbstractBeanDefinitionParser
 * 
 * @author william.liangf
 * @export
 */
public class DubboBeanDefinitionParser implements BeanDefinitionParser {
 
    private static final Logger logger = LoggerFactory.getLogger(DubboBeanDefinitionParser.class);
 
    private final Class<?> beanClass;
 
    private final boolean required;
 
    public DubboBeanDefinitionParser(Class<?> beanClass, boolean required) {
        this.beanClass = beanClass;
        this.required = required;
    }
 
    public BeanDefinition parse(Element element, ParserContext parserContext) {
        return parse(element, parserContext, beanClass, required);
    }
 
    @SuppressWarnings("unchecked")
    private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) {
        //略
    }

可以看到这个类实现了Spring的org.springframework.beans.factory.xml.BeanDefinitionParser接口，从而完成Spring Bean的解析工作。

而registerBeanDefinitionParser("annotation", new DubboBeanDefinitionParser(AnnotationBean.class, true));就是将<dubbo:annotation />标签，解析成com.alibaba.dubbo.config.spring.AnnotationBean并注册到Spring中。

3.AnnotationBean分析

先来看看源码： AnnotationBean.java

代码语言：javascript
复制
package com.alibaba.dubbo.config.spring;
 
 
 
/**
 * AnnotationBean
 * 
 * @author william.liangf
 * @export
 */
public class AnnotationBean extends AbstractConfig implements DisposableBean, BeanFactoryPostProcessor, BeanPostProcessor, ApplicationContextAware {
 
    private static final long serialVersionUID = -7582802454287589552L;
 
    private static final Logger logger = LoggerFactory.getLogger(Logger.class);
 
    private String annotationPackage;
 
    private String[] annotationPackages;
 
    private final Set<ServiceConfig<?>> serviceConfigs = new ConcurrentHashSet<ServiceConfig<?>>();
 
    private final ConcurrentMap<String, ReferenceBean<?>> referenceConfigs = new ConcurrentHashMap<String, ReferenceBean<?>>();
 
    public String getPackage() {
        return annotationPackage;
    }
 
    public void setPackage(String annotationPackage) {
        this.annotationPackage = annotationPackage;
        this.annotationPackages = (annotationPackage == null || annotationPackage.length() == 0) ? null
                : Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
    }
 
    private ApplicationContext applicationContext;
 
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
 
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
            throws BeansException {
        if (annotationPackage == null || annotationPackage.length() == 0) {
            return;
        }
        if (beanFactory instanceof BeanDefinitionRegistry) {
            try {
                // init scanner
                Class<?> scannerClass = ReflectUtils.forName("org.springframework.context.annotation.ClassPathBeanDefinitionScanner");
                Object scanner = scannerClass.getConstructor(new Class<?>[] {BeanDefinitionRegistry.class, boolean.class}).newInstance(new Object[] {(BeanDefinitionRegistry) beanFactory, true});
                // add filter
                Class<?> filterClass = ReflectUtils.forName("org.springframework.core.type.filter.AnnotationTypeFilter");
                Object filter = filterClass.getConstructor(Class.class).newInstance(Service.class);
                Method addIncludeFilter = scannerClass.getMethod("addIncludeFilter", ReflectUtils.forName("org.springframework.core.type.filter.TypeFilter"));
                addIncludeFilter.invoke(scanner, filter);
                // scan packages
                String[] packages = Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
                Method scan = scannerClass.getMethod("scan", new Class<?>[]{String[].class});
                scan.invoke(scanner, new Object[] {packages});
            } catch (Throwable e) {
                // spring 2.0
            }
        }
    }
 
    public void destroy() throws Exception {
        for (ServiceConfig<?> serviceConfig : serviceConfigs) {
            try {
                serviceConfig.unexport();
            } catch (Throwable e) {
                logger.error(e.getMessage(), e);
            }
        }
        for (ReferenceConfig<?> referenceConfig : referenceConfigs.values()) {
            try {
                referenceConfig.destroy();
            } catch (Throwable e) {
                logger.error(e.getMessage(), e);
            }
        }
    }
 
    public Object postProcessAfterInitialization(Object bean, String beanName)
            throws BeansException {
        if (! isMatchPackage(bean)) {
            return bean;
        }
        Service service = bean.getClass().getAnnotation(Service.class);
        if (service != null) {
            ServiceBean<Object> serviceConfig = new ServiceBean<Object>(service);
            if (void.class.equals(service.interfaceClass())
                    && "".equals(service.interfaceName())) {
                if (bean.getClass().getInterfaces().length > 0) {
                    serviceConfig.setInterface(bean.getClass().getInterfaces()[0]);
                } else {
                    throw new IllegalStateException("Failed to export remote service class " + bean.getClass().getName() + ", cause: The @Service undefined interfaceClass or interfaceName, and the service class unimplemented any interfaces.");
                }
            }
            if (applicationContext != null) {
                serviceConfig.setApplicationContext(applicationContext);
                if (service.registry() != null && service.registry().length > 0) {
                    List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
                    for (String registryId : service.registry()) {
                        if (registryId != null && registryId.length() > 0) {
                            registryConfigs.add((RegistryConfig)applicationContext.getBean(registryId, RegistryConfig.class));
                        }
                    }
                    serviceConfig.setRegistries(registryConfigs);
                }
                if (service.provider() != null && service.provider().length() > 0) {
                    serviceConfig.setProvider((ProviderConfig)applicationContext.getBean(service.provider(),ProviderConfig.class));
                }
                if (service.monitor() != null && service.monitor().length() > 0) {
                    serviceConfig.setMonitor((MonitorConfig)applicationContext.getBean(service.monitor(), MonitorConfig.class));
                }
                if (service.application() != null && service.application().length() > 0) {
                    serviceConfig.setApplication((ApplicationConfig)applicationContext.getBean(service.application(), ApplicationConfig.class));
                }
                if (service.module() != null && service.module().length() > 0) {
                    serviceConfig.setModule((ModuleConfig)applicationContext.getBean(service.module(), ModuleConfig.class));
                }
                if (service.provider() != null && service.provider().length() > 0) {
                    serviceConfig.setProvider((ProviderConfig)applicationContext.getBean(service.provider(), ProviderConfig.class));
                } else {
 
                }
                if (service.protocol() != null && service.protocol().length > 0) {
                    List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
                    for (String protocolId : service.registry()) {
                        if (protocolId != null && protocolId.length() > 0) {
                            protocolConfigs.add((ProtocolConfig)applicationContext.getBean(protocolId, ProtocolConfig.class));
                        }
                    }
                    serviceConfig.setProtocols(protocolConfigs);
                }
                try {
                    serviceConfig.afterPropertiesSet();
                } catch (RuntimeException e) {
                    throw (RuntimeException) e;
                } catch (Exception e) {
                    throw new IllegalStateException(e.getMessage(), e);
                }
            }
            serviceConfig.setRef(bean);
            serviceConfigs.add(serviceConfig);
            serviceConfig.export();
        }
        return bean;
    }
 
    public Object postProcessBeforeInitialization(Object bean, String beanName)
            throws BeansException {
        if (! isMatchPackage(bean)) {
            return bean;
        }
        Method[] methods = bean.getClass().getMethods();
        for (Method method : methods) {
            String name = method.getName();
            if (name.length() > 3 && name.startsWith("set")
                    && method.getParameterTypes().length == 1
                    && Modifier.isPublic(method.getModifiers())
                    && ! Modifier.isStatic(method.getModifiers())) {
                try {
                    Reference reference = method.getAnnotation(Reference.class);
                    if (reference != null) {
                        Object value = refer(reference, method.getParameterTypes()[0]);
                        if (value != null) {
                            method.invoke(bean, new Object[] {  });
                        }
                    }
                } catch (Throwable e) {
                    logger.error("Failed to init remote service reference at method " + name + " in class " + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
                }
            }
        }
        Field[] fields = bean.getClass().getDeclaredFields();
        for (Field field : fields) {
            try {
                if (! field.isAccessible()) {
                    field.setAccessible(true);
                }
                Reference reference = field.getAnnotation(Reference.class);
                if (reference != null) {
                    Object value = refer(reference, field.getType());
                    if (value != null) {
                        field.set(bean, value);
                    }
                }
            } catch (Throwable e) {
                logger.error("Failed to init remote service reference at filed " + field.getName() + " in class " + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
            }
        }
        return bean;
    }
 
    private Object refer(Reference reference, Class<?> referenceClass) { //method.getParameterTypes()[0]
        String interfaceName;
        if (! "".equals(reference.interfaceName())) {
            interfaceName = reference.interfaceName();
        } else if (! void.class.equals(reference.interfaceClass())) {
            interfaceName = reference.interfaceClass().getName();
        } else if (referenceClass.isInterface()) {
            interfaceName = referenceClass.getName();
        } else {
            throw new IllegalStateException("The @Reference undefined interfaceClass or interfaceName, and the property type " + referenceClass.getName() + " is not a interface.");
        }
        String key = reference.group() + "/" + interfaceName + ":" + reference.version();
        ReferenceBean<?> referenceConfig = referenceConfigs.get(key);
        if (referenceConfig == null) {
            referenceConfig = new ReferenceBean<Object>(reference);
            if (void.class.equals(reference.interfaceClass())
                    && "".equals(reference.interfaceName())
                    && referenceClass.isInterface()) {
                referenceConfig.setInterface(referenceClass);
            }
            if (applicationContext != null) {
                referenceConfig.setApplicationContext(applicationContext);
                if (reference.registry() != null && reference.registry().length > 0) {
                    List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
                    for (String registryId : reference.registry()) {
                        if (registryId != null && registryId.length() > 0) {
                            registryConfigs.add((RegistryConfig)applicationContext.getBean(registryId, RegistryConfig.class));
                        }
                    }
                    referenceConfig.setRegistries(registryConfigs);
                }
                if (reference.consumer() != null && reference.consumer().length() > 0) {
                    referenceConfig.setConsumer((ConsumerConfig)applicationContext.getBean(reference.consumer(), ConsumerConfig.class));
                }
                if (reference.monitor() != null && reference.monitor().length() > 0) {
                    referenceConfig.setMonitor((MonitorConfig)applicationContext.getBean(reference.monitor(), MonitorConfig.class));
                }
                if (reference.application() != null && reference.application().length() > 0) {
                    referenceConfig.setApplication((ApplicationConfig)applicationContext.getBean(reference.application(), ApplicationConfig.class));
                }
                if (reference.module() != null && reference.module().length() > 0) {
                    referenceConfig.setModule((ModuleConfig)applicationContext.getBean(reference.module(), ModuleConfig.class));
                }
                if (reference.consumer() != null && reference.consumer().length() > 0) {
                    referenceConfig.setConsumer((ConsumerConfig)applicationContext.getBean(reference.consumer(), ConsumerConfig.class));
                }
                try {
                    referenceConfig.afterPropertiesSet();
                } catch (RuntimeException e) {
                    throw (RuntimeException) e;
                } catch (Exception e) {
                    throw new IllegalStateException(e.getMessage(), e);
                }
            }
            referenceConfigs.putIfAbsent(key, referenceConfig);
            referenceConfig = referenceConfigs.get(key);
        }
        return referenceConfig.get();
    }
 
    private boolean isMatchPackage(Object bean) {
        if (annotationPackages == null || annotationPackages.length == 0) {
            return true;
        }
        String beanClassName = bean.getClass().getName();
        for (String pkg : annotationPackages) {
            if (beanClassName.startsWith(pkg)) {
                return true;
            }
        }
        return false;
    }
 
}

这个AnnotationBean实现了几个Spring生命周期接口，从而完成Dubbo整合Spring 的操作。 org.springframework.beans.factory.config.BeanFactoryPostProcessor 先来看看Spring文档中的介绍：

BeanFactoryPostProcessor operates on the bean configuration metadata; that is, the Spring IoC container allows a BeanFactoryPostProcessor to read the configuration metadata and potentially change it before the container instantiates any beans other than BeanFactoryPostProcessors.

翻译成中文就是：BeanFactoryPostProcessor可以用于在Spring IoC容器实例化Bean之前，对Spring Bean配置信息进行一些操作

通过Spring文档，可以清楚这个接口的功能，那再来看看Dubbo的AnnotationBean是如何实现这个接口的：

代码语言：javascript
复制
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
            throws BeansException {
    if (annotationPackage == null || annotationPackage.length() == 0) {
        return;
    }
    if (beanFactory instanceof BeanDefinitionRegistry) {
        try {
            // init scanner
            Class<?> scannerClass = ReflectUtils.forName("org.springframework.context.annotation.ClassPathBeanDefinitionScanner");
            Object scanner = scannerClass.getConstructor(new Class<?>[] {BeanDefinitionRegistry.class, boolean.class}).newInstance(new Object[] {(BeanDefinitionRegistry) beanFactory, true});
            // add filter
            Class<?> filterClass = ReflectUtils.forName("org.springframework.core.type.filter.AnnotationTypeFilter");
            Object filter = filterClass.getConstructor(Class.class).newInstance(Service.class);
            Method addIncludeFilter = scannerClass.getMethod("addIncludeFilter", ReflectUtils.forName("org.springframework.core.type.filter.TypeFilter"));
            addIncludeFilter.invoke(scanner, filter);
            // scan packages
            String[] packages = Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
            Method scan = scannerClass.getMethod("scan", new Class<?>[]{String[].class});
            scan.invoke(scanner, new Object[] {packages});
        } catch (Throwable e) {
            // spring 2.0
        }
    }
}

源码中已经标出了，Dubbo做了以下几件事：

  • 增加了一个class扫描器，用于处理Dubbo服务类的扫描
  • 增加过滤器，只扫描带有com.alibaba.dubbo.config.annotation.Service注解的class
  • 指定扫描的包，对应这<dubbo:annotation package="com.foo.bar.service" />标签中的package属性。

这个扫描器，就是将那些带有com.alibaba.dubbo.config.annotation.Service注解的class纳入Spring容器中，而这些Dubbo服务类上不需要单独加上Spring的注解，也不需要额外配置Spring Bean定义。

org.springframework.beans.factory.DisposableBean

再来看看这个接口，还是先看看Spring文档：

Implementing the org.springframework.beans.factory.DisposableBean interface allows a bean to get a callback when the container containing it is destroyed. The DisposableBean interface specifies a single method:void destroy() throws Exception;

这个接口实际上就是当Spring容器要销毁时的一个回调接口。 那再来看看Dubbo是如何实现的：

代码语言：javascript
复制
public void destroy() throws Exception {
    for (ServiceConfig<?> serviceConfig : serviceConfigs) {
        try {
            serviceConfig.unexport();
        } catch (Throwable e) {
            logger.error(e.getMessage(), e);
        }
    }
    for (ReferenceConfig<?> referenceConfig : referenceConfigs.values()) {
        try {
            referenceConfig.destroy();
        } catch (Throwable e) {
            logger.error(e.getMessage(), e);
        }
    }
}

也比较简单，实际上就是当Spring容器销毁时，对Dubbo服务进行反注册操作。 org.springframework.beans.factory.config.BeanPostProcessor 最后来看看这个接口，照例先看看Spring文档：

The BeanPostProcessor interface defines callback methods that you can implement to provide your own (or override the container’s default) instantiation logic, dependency-resolution logic, and so forth. If you want to implement some custom logic after the Spring container finishes instantiating, configuring, and initializing a bean, you can plug in one or more BeanPostProcessor implementations.

这个接口也是一个回调接口，只是回调时机不同，它发生在Spring容器初始化过程中，Bean实例化前后之时。也可以理解为Spring容器初始化完成后，Bean实例化前后但还没有给容器外使用前。 再来看看Dubbbo在这个时间点上做了什么：

代码语言：javascript
复制
public Object postProcessBeforeInitialization(Object bean, String beanName)
            throws BeansException {
    if (! isMatchPackage(bean)) {
        return bean;
    }
    Method[] methods = bean.getClass().getMethods();
    for (Method method : methods) {
        String name = method.getName();
        if (name.length() > 3 && name.startsWith("set")
                && method.getParameterTypes().length == 1
                && Modifier.isPublic(method.getModifiers())
                && ! Modifier.isStatic(method.getModifiers())) {
            try {
                Reference reference = method.getAnnotation(Reference.class);
                if (reference != null) {
                    Object value = refer(reference, method.getParameterTypes()[0]);
                    if (value != null) {
                        method.invoke(bean, new Object[] {  });
                    }
                }
            } catch (Throwable e) {
                logger.error("Failed to init remote service reference at method " + name + " in class " + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
            }
        }
    }
    Field[] fields = bean.getClass().getDeclaredFields();
    for (Field field : fields) {
        try {
            if (! field.isAccessible()) {
                field.setAccessible(true);
            }
            Reference reference = field.getAnnotation(Reference.class);
            if (reference != null) {
                Object value = refer(reference, field.getType());
                if (value != null) {
                    field.set(bean, value);
                }
            }
        } catch (Throwable e) {
            logger.error("Failed to init remote service reference at filed " + field.getName() + " in class " + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
        }
    }
    return bean;
}

postProcessBeforeInitialization方法，顾名思义，发生Bean实例化之前。通过源码就可以发现，主要用于处理Bean中的com.alibaba.dubbo.config.annotation.Reference注解，从而让Dubbo服务能够注入到Bean中。期间利用JAVA反射机制对Bean的方法和属性进行注入。

代码语言：javascript
复制
public Object postProcessAfterInitialization(Object bean, String beanName)
            throws BeansException {
    if (! isMatchPackage(bean)) {
        return bean;
    }
    Service service = bean.getClass().getAnnotation(Service.class);
    if (service != null) {
        ServiceBean<Object> serviceConfig = new ServiceBean<Object>(service);
        if (void.class.equals(service.interfaceClass())
                && "".equals(service.interfaceName())) {
            if (bean.getClass().getInterfaces().length > 0) {
                serviceConfig.setInterface(bean.getClass().getInterfaces()[0]);
            } else {
                throw new IllegalStateException("Failed to export remote service class " + bean.getClass().getName() + ", cause: The @Service undefined interfaceClass or interfaceName, and the service class unimplemented any interfaces.");
            }
        }
        if (applicationContext != null) {
            serviceConfig.setApplicationContext(applicationContext);
            if (service.registry() != null && service.registry().length > 0) {
                List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
                for (String registryId : service.registry()) {
                    if (registryId != null && registryId.length() > 0) {
                        registryConfigs.add((RegistryConfig)applicationContext.getBean(registryId, RegistryConfig.class));
                    }
                }
                serviceConfig.setRegistries(registryConfigs);
            }
            if (service.provider() != null && service.provider().length() > 0) {
                serviceConfig.setProvider((ProviderConfig)applicationContext.getBean(service.provider(),ProviderConfig.class));
            }
            if (service.monitor() != null && service.monitor().length() > 0) {
                serviceConfig.setMonitor((MonitorConfig)applicationContext.getBean(service.monitor(), MonitorConfig.class));
            }
            if (service.application() != null && service.application().length() > 0) {
                serviceConfig.setApplication((ApplicationConfig)applicationContext.getBean(service.application(), ApplicationConfig.class));
            }
            if (service.module() != null && service.module().length() > 0) {
                serviceConfig.setModule((ModuleConfig)applicationContext.getBean(service.module(), ModuleConfig.class));
            }
            if (service.provider() != null && service.provider().length() > 0) {
                serviceConfig.setProvider((ProviderConfig)applicationContext.getBean(service.provider(), ProviderConfig.class));
            } else {
 
            }
            if (service.protocol() != null && service.protocol().length > 0) {
                List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
                for (String protocolId : service.registry()) {
                    if (protocolId != null && protocolId.length() > 0) {
                        protocolConfigs.add((ProtocolConfig)applicationContext.getBean(protocolId, ProtocolConfig.class));
                    }
                }
                serviceConfig.setProtocols(protocolConfigs);
            }
            try {
                serviceConfig.afterPropertiesSet();
            } catch (RuntimeException e) {
                throw (RuntimeException) e;
            } catch (Exception e) {
                throw new IllegalStateException(e.getMessage(), e);
            }
        }
        serviceConfig.setRef(bean);
        serviceConfigs.add(serviceConfig);
        serviceConfig.export();
    }
    return bean;
}

postProcessAfterInitialization方法，同样从名字就能看出，其发生在Bean实例化之后。通过源码就能发现，其作用就是将带有com.alibaba.dubbo.config.annotation.Service注解的Bean自动注册到Dubbo的注册中心，完成服务注册动作。

4.问题分析

通过上面的分析，对于Dubbo注解方式整合到Spring已经比较清楚了。而在使用高版本Spring时，上面的AnnotationBean会出现一些问题。

问题主要集中在：

  • Dubbo的注解Service有时不能进行服务注册
  • Dubbo的注解Reference有时不能注入服务

从代码分析问题主要集中在postProcessBeforeInitialization和postProcessAfterInitialization方法上。

代码语言：javascript
复制
Service service = bean.getClass().getAnnotation(Service.class);
代码语言：javascript
复制
Method[] methods = bean.getClass().getMethods();

方法中都是利用Java反射来处理Bean的Class。

众所周知，Spring有两大利器IOC和AOP。在早期AOP基本都是利用JAVA动态代理实现的，而随着字节码技术的发展，现在Spring已经基本以ASM为代表的字节码增强框架为基础实现AOP,以及一些Bean的代理。

有兴趣的小伙伴可以打开spring-core-x.x.x.jar,会发现spring已经内嵌了asm以及cglib （org.springframework.asm）（org.springframework.cglib）

而在Spring环境中大量出现经过Cglib增强的Class，这些Class不再是简单的基于接口的代理机制了，其内部大量使用委派方式，以及访问器模式。最常见的就是Spring的事物，对于使用了@Transactional的Bean，都是以这种方式来增加事物处理能力的。

那基于这种方式扩展的Class，再通过反射getClass得到的是经过cglib改写后的class。在这些class上getAnnotation以及getMethods都不再是预期中的结果了。

所以，这也也就导致了上面罗列的两个问题。

5. 解决方案

经过对问题的分析，可以发现，问题主要是集中在Dubbo获取Bean的class上。

在Spring中，提供了很多Utils类。其中org.springframework.aop.support.AopUtils就可以用来对Aop代理的类进行操作的API。

于是，我们可以利用这个类来完成Class的获取。

代码语言：javascript
复制
private Class<?> getBeanClass(Object bean) {
    Class<?> clazz = bean.getClass();
    if (AopUtils.isAopProxy(bean)) {
        clazz = AopUtils.getTargetClass(bean);
    }
    return clazz;
}

这样获取Class就可以这样：

代码语言：javascript
复制
Class<?> clazz = getBeanClass(bean);
Service service = clazz.getAnnotation(Service.class);
代码语言：javascript
复制
Class<?> clazz = getBeanClass(bean);

修改后完整的代码： AnnotationBean.java

代码语言：javascript
复制
/*
 * Copyright 1999-2012 Alibaba Group.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.roc.dubbo.config.spring;
 
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
 
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
 
import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.common.utils.ConcurrentHashSet;
import com.alibaba.dubbo.common.utils.ReflectUtils;
import com.alibaba.dubbo.config.AbstractConfig;
import com.alibaba.dubbo.config.ApplicationConfig;
import com.alibaba.dubbo.config.ConsumerConfig;
import com.alibaba.dubbo.config.ModuleConfig;
import com.alibaba.dubbo.config.MonitorConfig;
import com.alibaba.dubbo.config.ProtocolConfig;
import com.alibaba.dubbo.config.ProviderConfig;
import com.alibaba.dubbo.config.ReferenceConfig;
import com.alibaba.dubbo.config.RegistryConfig;
import com.alibaba.dubbo.config.ServiceConfig;
import com.alibaba.dubbo.config.annotation.Reference;
import com.alibaba.dubbo.config.annotation.Service;
import com.alibaba.dubbo.config.spring.ReferenceBean;
import com.alibaba.dubbo.config.spring.ServiceBean;
 
/**
 * AnnotationBean
 * 
 * @author william.liangf
 * @export
 * 
 *         >>>修复@com.alibaba.dubbo.config.annotation.Service
 *         与Spring @Transactional 冲突
 */
public class AnnotationBean extends AbstractConfig
        implements DisposableBean, BeanFactoryPostProcessor, BeanPostProcessor, ApplicationContextAware {
 
    private static final long serialVersionUID = -7582802454287589552L;
 
    private static final Logger logger = LoggerFactory.getLogger(Logger.class);
 
    private String annotationPackage;
 
    private String[] annotationPackages;
 
    private final Set<ServiceConfig<?>> serviceConfigs = new ConcurrentHashSet<ServiceConfig<?>>();
 
    private final ConcurrentMap<String, ReferenceBean<?>> referenceConfigs = new ConcurrentHashMap<String, ReferenceBean<?>>();
 
    public String getPackage() {
        return annotationPackage;
    }
 
    public void setPackage(String annotationPackage) {
        this.annotationPackage = annotationPackage;
        this.annotationPackages = (annotationPackage == null || annotationPackage.length() == 0) ? null
                : Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
    }
 
    private ApplicationContext applicationContext;
 
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
 
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        if (annotationPackage == null || annotationPackage.length() == 0) {
            logger.debug("未定义注解扫描包");
            return;
        }
        logger.info("扫描：" + annotationPackage);
        if (beanFactory instanceof BeanDefinitionRegistry) {
            try {
                // init scanner
                Class<?> scannerClass = ReflectUtils
                        .forName("org.springframework.context.annotation.ClassPathBeanDefinitionScanner");
                Object scanner = scannerClass
                        .getConstructor(new Class<?>[] { BeanDefinitionRegistry.class, boolean.class })
                        .newInstance(new Object[] { (BeanDefinitionRegistry) beanFactory, true });
                // add filter
                Class<?> filterClass = ReflectUtils
                        .forName("org.springframework.core.type.filter.AnnotationTypeFilter");
                Object filter = filterClass.getConstructor(Class.class).newInstance(Service.class);
                Method addIncludeFilter = scannerClass.getMethod("addIncludeFilter",
                        ReflectUtils.forName("org.springframework.core.type.filter.TypeFilter"));
                addIncludeFilter.invoke(scanner, filter);
                // scan packages
                String[] packages = Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
                Method scan = scannerClass.getMethod("scan", new Class<?>[] { String[].class });
                scan.invoke(scanner, new Object[] { packages });
            } catch (Throwable e) {
                // spring 2.0
            }
        }
    }
 
    public void destroy() throws Exception {
        for (ServiceConfig<?> serviceConfig : serviceConfigs) {
            try {
                serviceConfig.unexport();
            } catch (Throwable e) {
                logger.error(e.getMessage(), e);
            }
        }
        for (ReferenceConfig<?> referenceConfig : referenceConfigs.values()) {
            try {
                referenceConfig.destroy();
            } catch (Throwable e) {
                logger.error(e.getMessage(), e);
            }
        }
    }
 
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (!isMatchPackage(bean)) {
            return bean;
        }
        Class<?> clazz = getBeanClass(bean);
        Service service = clazz.getAnnotation(Service.class);
        // >>>>>>>>>>>>>>>>>>
        if (service != null) {
            ServiceBean<Object> serviceConfig = new ServiceBean<Object>(service);
            if (void.class.equals(service.interfaceClass()) && "".equals(service.interfaceName())) {
                if (bean.getClass().getInterfaces().length > 0) {
                    serviceConfig.setInterface(bean.getClass().getInterfaces()[0]);
                } else {
                    throw new IllegalStateException("Failed to export remote service class " + bean.getClass().getName()
                            + ", cause: The @Service undefined interfaceClass or interfaceName, and the service class unimplemented any interfaces.");
                }
            }
            if (applicationContext != null) {
                serviceConfig.setApplicationContext(applicationContext);
                if (service.registry() != null && service.registry().length > 0) {
                    List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
                    for (String registryId : service.registry()) {
                        if (registryId != null && registryId.length() > 0) {
                            registryConfigs
                                    .add((RegistryConfig) applicationContext.getBean(registryId, RegistryConfig.class));
                        }
                    }
                    serviceConfig.setRegistries(registryConfigs);
                }
                if (service.provider() != null && service.provider().length() > 0) {
                    serviceConfig.setProvider(
                            (ProviderConfig) applicationContext.getBean(service.provider(), ProviderConfig.class));
                }
                if (service.monitor() != null && service.monitor().length() > 0) {
                    serviceConfig.setMonitor(
                            (MonitorConfig) applicationContext.getBean(service.monitor(), MonitorConfig.class));
                }
                if (service.application() != null && service.application().length() > 0) {
                    serviceConfig.setApplication((ApplicationConfig) applicationContext.getBean(service.application(),
                            ApplicationConfig.class));
                }
                if (service.module() != null && service.module().length() > 0) {
                    serviceConfig
                            .setModule((ModuleConfig) applicationContext.getBean(service.module(), ModuleConfig.class));
                }
                if (service.provider() != null && service.provider().length() > 0) {
                    serviceConfig.setProvider(
                            (ProviderConfig) applicationContext.getBean(service.provider(), ProviderConfig.class));
                } else {
 
                }
                if (service.protocol() != null && service.protocol().length > 0) {
                    List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
                    for (String protocolId : service.registry()) {
                        if (protocolId != null && protocolId.length() > 0) {
                            protocolConfigs
                                    .add((ProtocolConfig) applicationContext.getBean(protocolId, ProtocolConfig.class));
                        }
                    }
                    serviceConfig.setProtocols(protocolConfigs);
                }
                try {
                    serviceConfig.afterPropertiesSet();
                } catch (RuntimeException e) {
                    throw (RuntimeException) e;
                } catch (Exception e) {
                    throw new IllegalStateException(e.getMessage(), e);
                }
            }
            serviceConfig.setRef(bean);
            serviceConfigs.add(serviceConfig);
            serviceConfig.export();
        }
        return bean;
    }
 
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        // logger.debug("扫描bean:"+bean);
        // System.out.println("扫描bean:"+bean);
        if (!isMatchPackage(bean)) {
            return bean;
        }
        // >>>>>>>>>>>>>>>>>>>>>>>>
        Class<?> clazz = getBeanClass(bean);
        // >>>>>>>>>>>>>>>>>>>>>>>>
        Method[] methods = clazz.getMethods();
        for (Method method : methods) {
            String name = method.getName();
            if (name.length() > 3 && name.startsWith("set") && method.getParameterTypes().length == 1
                    && Modifier.isPublic(method.getModifiers()) && !Modifier.isStatic(method.getModifiers())) {
                try {
                    Reference reference = method.getAnnotation(Reference.class);
                    if (reference != null) {
                        Object value = refer(reference, method.getParameterTypes()[0]);
                        if (value != null) {
                            method.invoke(bean, new Object[] {});
                        }
                    }
                } catch (Throwable e) {
                    logger.error("Failed to init remote service reference at method " + name + " in class "
                            + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
                }
            }
        }
        // >>>>>>>>>>>>>>>>>>>>>>>>
        Field[] fields = clazz.getDeclaredFields();
        for (Field field : fields) {
            try {
                if (!field.isAccessible()) {
                    field.setAccessible(true);
                }
                Reference reference = field.getAnnotation(Reference.class);
                if (reference != null) {
                    Object value = refer(reference, field.getType());
                    if (value != null) {
                        field.set(bean, value);
                    }
                }
            } catch (Throwable e) {
                logger.error("Failed to init remote service reference at filed " + field.getName() + " in class "
                        + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
            }
        }
        return bean;
    }
 
    private Object refer(Reference reference, Class<?> referenceClass) { // method.getParameterTypes()[0]
        String interfaceName;
        if (!"".equals(reference.interfaceName())) {
            interfaceName = reference.interfaceName();
        } else if (!void.class.equals(reference.interfaceClass())) {
            interfaceName = reference.interfaceClass().getName();
        } else if (referenceClass.isInterface()) {
            interfaceName = referenceClass.getName();
        } else {
            throw new IllegalStateException(
                    "The @Reference undefined interfaceClass or interfaceName, and the property type "
                            + referenceClass.getName() + " is not a interface.");
        }
        String key = reference.group() + "/" + interfaceName + ":" + reference.version();
        ReferenceBean<?> referenceConfig = referenceConfigs.get(key);
        if (referenceConfig == null) {
            referenceConfig = new ReferenceBean<Object>(reference);
            if (void.class.equals(reference.interfaceClass()) && "".equals(reference.interfaceName())
                    && referenceClass.isInterface()) {
                referenceConfig.setInterface(referenceClass);
            }
            if (applicationContext != null) {
                referenceConfig.setApplicationContext(applicationContext);
                if (reference.registry() != null && reference.registry().length > 0) {
                    List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
                    for (String registryId : reference.registry()) {
                        if (registryId != null && registryId.length() > 0) {
                            registryConfigs
                                    .add((RegistryConfig) applicationContext.getBean(registryId, RegistryConfig.class));
                        }
                    }
                    referenceConfig.setRegistries(registryConfigs);
                }
                if (reference.consumer() != null && reference.consumer().length() > 0) {
                    referenceConfig.setConsumer(
                            (ConsumerConfig) applicationContext.getBean(reference.consumer(), ConsumerConfig.class));
                }
                if (reference.monitor() != null && reference.monitor().length() > 0) {
                    referenceConfig.setMonitor(
                            (MonitorConfig) applicationContext.getBean(reference.monitor(), MonitorConfig.class));
                }
                if (reference.application() != null && reference.application().length() > 0) {
                    referenceConfig.setApplication((ApplicationConfig) applicationContext
                            .getBean(reference.application(), ApplicationConfig.class));
                }
                if (reference.module() != null && reference.module().length() > 0) {
                    referenceConfig.setModule(
                            (ModuleConfig) applicationContext.getBean(reference.module(), ModuleConfig.class));
                }
                if (reference.consumer() != null && reference.consumer().length() > 0) {
                    referenceConfig.setConsumer(
                            (ConsumerConfig) applicationContext.getBean(reference.consumer(), ConsumerConfig.class));
                }
                try {
                    referenceConfig.afterPropertiesSet();
                } catch (RuntimeException e) {
                    throw (RuntimeException) e;
                } catch (Exception e) {
                    throw new IllegalStateException(e.getMessage(), e);
                }
            }
            referenceConfigs.putIfAbsent(key, referenceConfig);
            referenceConfig = referenceConfigs.get(key);
        }
        return referenceConfig.get();
    }
 
    private boolean isMatchPackage(Object bean) {
        if (annotationPackages == null || annotationPackages.length == 0) {
            return true;
        }
        Class<?> clazz = getBeanClass(bean);
        String beanClassName = clazz.getName();
        for (String pkg : annotationPackages) {
            if (beanClassName.startsWith(pkg)) {
                return true;
            }
        }
        return false;
    }
 
    private Class<?> getBeanClass(Object bean) {
        Class<?> clazz = bean.getClass();
        if (AopUtils.isAopProxy(bean)) {
            clazz = AopUtils.getTargetClass(bean);
        }
        return clazz;
    }
 
}

6. 整合

同样，我不太赞同自己修改Dubbo源码，然后打包。侵入性太强。通过前面几节的分析发现，其实只要AnnotationBean能够注册到Spring环境就行。而AnnotationBean无所谓放在哪个jar中。

所以，完全可以把修改后的AnnotationBean打入到自己写的jar中，然后注入Spring环境，以外挂的方式完成修改。

下面示例代码展示了，在Spring Boot中以外挂方式整合：

代码语言：javascript
复制
package com.roc.dubbo.boot.configuration;
 
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import com.roc.dubbo.config.spring.AnnotationBean;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
 
/**
 * @author binghe
 * @description 以外挂方式整合修改后的Dubbo源码
 */
@Configuration
@Import(DubboBasicConfiguration.class)
@AutoConfigureAfter(DubboBasicConfiguration.class)
public class DubboConfiguration {
 
    private final Logger logger = LogManager.getLogger(getClass());
 
    @Bean
    // @DependsOn("dubboConfiguration")
    public AnnotationBean dubboAnnotationBean() {
        AnnotationBean annotationBean = new AnnotationBean();
        // annotationBean.setApplicationContext(applicationContext);
        // annotationBean.setPackage(dubboProperties.getAnnotationPackage());
        // annotationBean.setPackage("com.roc.pay");
        logger.info("加入自定义" + annotationBean);
        return annotationBean;
    }
 
}
本文参与 腾讯云自媒体分享计划，分享自微信公众号。
原始发表：2019-12-20，如有侵权请联系 cloudcommunity@tencent.com 删除
spring
spring boot
dubbo
容器
java

本文分享自 冰河技术 微信公众号，前往查看

如有侵权，请联系 cloudcommunity@tencent.com 删除。

本文参与 腾讯云自媒体分享计划  ，欢迎热爱写作的你一起参与！

spring
spring boot
dubbo
容器
java
评论
登录后参与评论
0 条评论
热度
最新
登录 后参与评论
推荐阅读
LV.
文章
0
获赞
0
目录
  • 1.Dubbo原生的注解配置
  • 3.AnnotationBean分析
相关产品与服务
容器服务
腾讯云容器服务（Tencent Kubernetes Engine, TKE）基于原生 kubernetes 提供以容器为核心的、高度可扩展的高性能容器管理服务，覆盖 Serverless、边缘计算、分布式云等多种业务部署场景，业内首创单个集群兼容多种计算节点的容器资源管理模式。同时产品作为云原生 Finops 领先布道者，主导开源项目Crane，全面助力客户实现资源优化、成本控制。
产品介绍产品文档
精选特惠 用云无忧
领券

腾讯云开发者

扫码关注腾讯云开发者

扫码关注腾讯云开发者

领取腾讯云代金券

热门产品

热门推荐

更多推荐

Copyright © 2013 - 2024 Tencent Cloud. All Rights Reserved. 腾讯云 版权所有 

深圳市腾讯计算机系统有限公司 ICP备案/许可证号：粤B2-20090059 深公网安备号 44030502008569

腾讯云计算（北京）有限责任公司 京ICP证150476号 |  京ICP备11018762号 | 京公网安备号11010802020287

问题归档专栏文章快讯文章归档关键词归档开发者手册归档开发者手册 Section 归档

Copyright © 2013 - 2024 Tencent Cloud.

All Rights Reserved. 腾讯云 版权所有

登录 后参与评论