【SpringBoot（二）】带你认识Yaml配置文件类型、SpringMVC的资源访问路径 和 静态资源配置的原理！

k: v

行内写法：k: {k1:v1,k2:v2,k3:v3}
# 或
k:
	k1: v1
	k2: v2
	k3: v3

行内写法：k: [v1,v2,v3]
# 或者
k:
	- v1
	- v2
	- v3

person:
    name: zhangsan
    boss: true
    age: 21
    birthdate: 2022/12/9
    interests:
      - 篮球
      - 足球
      - 羽毛球
      - 数字18
    animal: [猫,狗]
    score:
        english: 80
        math: 90
    salarys: [8822,1290]
    pet:
      name: 旺旺
      weight: 99.1
    allpets:
      sick:
        - {name: 小蓝,weight: 92}
        - name: 小红
          weight: 80
        - name: 小黑
          weight: 89
      health: [{name: 小花,weight:90},{name: 小白,weight: 88}]

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>

<!--######################### 插件 ###############################-->
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <!-- 在打包时，防止 SpringBoot 加载过多的类 -->
            <configuration>
                <excludes>
                    <exclude>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-configuration-processor</artifactId>
                    </exclude>
                </excludes>
            </configuration>
        </plugin>
    </plugins>
</build>

spring:
  resources:
    static-locations: [ classpath: /haha/]

spring:
  mvc:
    static-path-pattern: /res/**

<dependency>
    <groupId>org.webjars.npm</groupId>
    <artifactId>jquery</artifactId>
    <version>3.6.0</version>
</dependency>

@AutoConfiguration(
    after = {DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class, ValidationAutoConfiguration.class}
)
@ConditionalOnWebApplication(
    type = Type.SERVLET
)
@ConditionalOnClass({Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class})
@ConditionalOnMissingBean({WebMvcConfigurationSupport.class})
@AutoConfigureOrder(-2147483638)
public class WebMvcAutoConfiguration {}

@Configuration(
    proxyBeanMethods = false
)
@Import({WebMvcAutoConfiguration.EnableWebMvcConfiguration.class})
@EnableConfigurationProperties({WebMvcProperties.class, WebProperties.class})
@Order(0)
public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer, ServletContextAware {}

public WebMvcAutoConfigurationAdapter(WebProperties webProperties, WebMvcProperties mvcProperties, ListableBeanFactory beanFactory, ObjectProvider<HttpMessageConverters> messageConvertersProvider, ObjectProvider<WebMvcAutoConfiguration.ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider, ObjectProvider<DispatcherServletPath> dispatcherServletPath, ObjectProvider<ServletRegistrationBean<?>> servletRegistrations) {
    this.resourceProperties = webProperties.getResources();
    this.mvcProperties = mvcProperties;
    this.beanFactory = beanFactory;
    this.messageConvertersProvider = messageConvertersProvider;
    this.resourceHandlerRegistrationCustomizer = (WebMvcAutoConfiguration.ResourceHandlerRegistrationCustomizer)resourceHandlerRegistrationCustomizerProvider.getIfAvailable();
    this.dispatcherServletPath = dispatcherServletPath;
    this.servletRegistrations = servletRegistrations;
    this.mvcProperties.checkConfiguration();
}

public void addResourceHandlers(ResourceHandlerRegistry registry) {
    // 获取静态资源的 add-mappings 属性，如果为false，那么所有的静态资源都被禁用了
    if (!this.resourceProperties.isAddMappings()) {
        logger.debug("Default resource handling disabled");
    } else {
        // 配置 webjars 的默认路径
        this.addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
        
        // 配置 静态资源 的访问路径
        this.addResourceHandler(registry, this.mvcProperties.getStaticPathPattern(), (registration) -> {
            registration.addResourceLocations(this.resourceProperties.getStaticLocations());
            if (this.servletContext != null) {
                ServletContextResource resource = new ServletContextResource(this.servletContext, "/");
                registration.addResourceLocations(new Resource[]{resource});
            }

        });
    }
}

spring:
  web:
    resources:
      add-mappings: false

public static class Resources {
        private static final String[] CLASSPATH_RESOURCE_LOCATIONS = new String[]{"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"};
    
        private String[] staticLocations;
        private boolean addMappings;
        private boolean customized;
        private final WebProperties.Resources.Chain chain;
        private final WebProperties.Resources.Cache cache;

        public Resources() {
            this.staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
            this.addMappings = true;
            this.customized = false;
            this.chain = new WebProperties.Resources.Chain();
            this.cache = new WebProperties.Resources.Cache();
        }

        public String[] getStaticLocations() {
            // 返回默认路径
            return this.staticLocations;
        }

// HandlerMapping：处理映射，保存了每一个 Handler 能处理哪些请求

@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext, FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
    WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(new TemplateAvailabilityProviders(applicationContext), applicationContext, this.getWelcomePage(), this.mvcProperties.getStaticPathPattern());
    welcomePageHandlerMapping.setInterceptors(this.getInterceptors(mvcConversionService, mvcResourceUrlProvider));
    welcomePageHandlerMapping.setCorsConfigurations(this.getCorsConfigurations());
    return welcomePageHandlerMapping;
}

// ###################### 构造器 ######################## 
WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders, ApplicationContext applicationContext, Resource welcomePage, String staticPathPattern) {
    // 要用欢迎页功能，路径必须是 /**
    if (welcomePage != null && "/**".equals(staticPathPattern)) {
        logger.info("Adding welcome page: " + welcomePage);
        this.setRootViewName("forward:index.html");
    } else if (this.welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
        //调用 Controller /index
        
        logger.info("Adding welcome page template: index");
        this.setRootViewName("index");
    }
}