SpringMVC源码-AbstractHandlerMethodMapping处理器映射器将@Controller修饰类方法存储到处理器映射器

SpringMVC九大内置组件之HandlerMapping处理器映射器-AbstractHandlerMethodMapping类以及子类RequestMappingHandlerMapping如何将@Controller修饰的注解类以及类下被注解RequestMapping修饰的方法存储到处理器映射器中。

从RequestMappingHandlerMapping寻找:

AbstractHandlerMethodMapping类的mappingRegistry什么时候赋值的呢？

AbstractHandlerMethodMapping类以及子类RequestMappingHandlerMapping的类关系图如下，实现了InitializingBean接口，那么该映射器在SpringMVC容器中进行9大组件初始化的时候肯定会调用该afterPropertiesSet方法。

调用链路如下，在启动项目的时候，先进行Spring父容器的刷新，然后进行SpringMVC子容器的刷新，在子容器中监听器会进行调用9大组件初始化代码(initStrategies)。初始化 HandlerMapping:映射器(initHandlerMappings）,配置文件没有配置就获取默认的，实例化属性填充之后进行初始化的设置，调用InitializingBean接口。开始完成@Controller注解进行方法和controller的映射关系，便于在后续进行http接口调用的时候，根据请求路径找到方法名从而获取到对行的controller类去执行方法

InitializingBean接口的afterPropertiesSet方法:200, RequestMappingHandlerMapping (org.springframework.web.servlet.mvc.method.annotation)
invokeInitMethods:2352, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
调用初始化方法，先调用bean的InitializingBean接口方法，后调用bean的自定义初始化方法 initializeBean:2261, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
doCreateBean:736, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
createBean:630, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
createBean:361, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
createDefaultStrategy:957, DispatcherServlet (org.springframework.web.servlet)
getDefaultStrategies:925, DispatcherServlet (org.springframework.web.servlet)
初始化 HandlerMapping:映射器，用来将对应的request跟controller进行对应initHandlerMappings:657, DispatcherServlet (org.springframework.web.servlet)
initStrategies:529, DispatcherServlet (org.springframework.web.servlet)
onRefresh:514, DispatcherServlet (org.springframework.web.servlet)
onApplicationEvent:901, FrameworkServlet (org.springframework.web.servlet)
onApplicationEvent:1277, FrameworkServlet$ContextRefreshListener (org.springframework.web.servlet)
onApplicationEvent:1273, FrameworkServlet$ContextRefreshListener (org.springframework.web.servlet)
onApplicationEvent:64, GenericApplicationListenerAdapter (org.springframework.context.event)
onApplicationEventInternal:109, SourceFilteringListener (org.springframework.context.event)
onApplicationEvent:73, SourceFilteringListener (org.springframework.context.event)
doInvokeListener:215, SimpleApplicationEventMulticaster (org.springframework.context.event)
invokeListener:202, SimpleApplicationEventMulticaster (org.springframework.context.event)
multicastEvent:164, SimpleApplicationEventMulticaster (org.springframework.context.event)
publishEvent:440, AbstractApplicationContext (org.springframework.context.support)
publishEvent:379, AbstractApplicationContext (org.springframework.context.support)
finishRefresh:1053, AbstractApplicationContext (org.springframework.context.support)
refresh:618, AbstractApplicationContext (org.springframework.context.support)
configureAndRefreshWebApplicationContext:759, FrameworkServlet (org.springframework.web.servlet)
createWebApplicationContext:715, FrameworkServlet (org.springframework.web.servlet)
createWebApplicationContext:773, FrameworkServlet (org.springframework.web.servlet)
initWebApplicationContext:625, FrameworkServlet (org.springframework.web.servlet)
initServletBean:536, FrameworkServlet (org.springframework.web.servlet)
init:185, HttpServletBean (org.springframework.web.servlet)
init:158, GenericServlet (javax.servlet)
initServlet:1164, StandardWrapper (org.apache.catalina.core)
loadServlet:1117, StandardWrapper (org.apache.catalina.core)
load:1010, StandardWrapper (org.apache.catalina.core)
loadOnStartup:4957, StandardContext (org.apache.catalina.core)
startInternal:5264, StandardContext (org.apache.catalina.core)
start:183, LifecycleBase (org.apache.catalina.util)
addChildInternal:726, ContainerBase (org.apache.catalina.core)
addChild:698, ContainerBase (org.apache.catalina.core)
addChild:696, StandardHost (org.apache.catalina.core)
manageApp:1783, HostConfig (org.apache.catalina.startup)
invoke0:-1, NativeMethodAccessorImpl (sun.reflect)
invoke:62, NativeMethodAccessorImpl (sun.reflect)
invoke:43, DelegatingMethodAccessorImpl (sun.reflect)
invoke:498, Method (java.lang.reflect)
invoke:293, BaseModelMBean (org.apache.tomcat.util.modeler)
invoke:819, DefaultMBeanServerInterceptor (com.sun.jmx.interceptor)
invoke:801, JmxMBeanServer (com.sun.jmx.mbeanserver)
createStandardContext:460, MBeanFactory (org.apache.catalina.mbeans)
createStandardContext:408, MBeanFactory (org.apache.catalina.mbeans)
invoke0:-1, NativeMethodAccessorImpl (sun.reflect)
invoke:62, NativeMethodAccessorImpl (sun.reflect)
invoke:43, DelegatingMethodAccessorImpl (sun.reflect)
invoke:498, Method (java.lang.reflect)
invoke:293, BaseModelMBean (org.apache.tomcat.util.modeler)
invoke:819, DefaultMBeanServerInterceptor (com.sun.jmx.interceptor)
invoke:801, JmxMBeanServer (com.sun.jmx.mbeanserver)
invoke:468, MBeanServerAccessController (com.sun.jmx.remote.security)
doOperation:1468, RMIConnectionImpl (javax.management.remote.rmi)
access$300:76, RMIConnectionImpl (javax.management.remote.rmi)
run:1309, RMIConnectionImpl$PrivilegedOperation (javax.management.remote.rmi)
doPrivileged:-1, AccessController (java.security)
doPrivilegedOperation:1408, RMIConnectionImpl (javax.management.remote.rmi)
invoke:829, RMIConnectionImpl (javax.management.remote.rmi)
invoke0:-1, NativeMethodAccessorImpl (sun.reflect)
invoke:62, NativeMethodAccessorImpl (sun.reflect)
invoke:43, DelegatingMethodAccessorImpl (sun.reflect)
invoke:498, Method (java.lang.reflect)
dispatch:346, UnicastServerRef (sun.rmi.server)
run:200, Transport$1 (sun.rmi.transport)
run:197, Transport$1 (sun.rmi.transport)
doPrivileged:-1, AccessController (java.security)
serviceCall:196, Transport (sun.rmi.transport)
handleMessages:568, TCPTransport (sun.rmi.transport.tcp)
run0:826, TCPTransport$ConnectionHandler (sun.rmi.transport.tcp)
lambda$run$0:683, TCPTransport$ConnectionHandler (sun.rmi.transport.tcp)
run:-1, 1316528462 (sun.rmi.transport.tcp.TCPTransport$ConnectionHandler$$Lambda$25)
doPrivileged:-1, AccessController (java.security)
run:682, TCPTransport$ConnectionHandler (sun.rmi.transport.tcp)
runWorker:1142, ThreadPoolExecutor (java.util.concurrent)
run:617, ThreadPoolExecutor$Worker (java.util.concurrent)
run:748, Thread (java.lang)

去父类AbstractHandlerMethodMapping类中去调用

在初始化时检测处理程序方法。

扫描ApplicationContext中的bean，检测和注册处理程序方法

判断 Bean 是否为处理器（例如有 @Controller 或者 @RequestMapping 注解）

	@Override
	protected boolean isHandler(Class<?> beanType) {
		// 判断是否有 @Controller 或者 @RequestMapping 的注解
		return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||
				AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));
	}

找到controller类上的方法去存储到处理器映射器中:

	/**
	 * Uses method and type-level @{@link RequestMapping} annotations to create
	 * the RequestMappingInfo.
	 * @return the created RequestMappingInfo, or {@code null} if the method
	 * does not have a {@code @RequestMapping} annotation.
	 * @see #getCustomMethodCondition(Method)
	 * @see #getCustomTypeCondition(Class)
	 */
	@Override
	@Nullable
	protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
		// 基于方法上的 @RequestMapping 注解，创建 RequestMappingInfo 对象
		RequestMappingInfo info = createRequestMappingInfo(method);
		if (info != null) {
			// 基于类上的 @RequestMapping 注解，合并进去
			RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);
			if (typeInfo != null) {
				info = typeInfo.combine(info);
			}
			// 如果有前缀，则设置到 info 中
			String prefix = getPathPrefix(handlerType);
			if (prefix != null) {
				info = RequestMappingInfo.paths(prefix).options(this.config).build().combine(info);
			}
		}
		return info;
	}

	/**
	 * Delegates to {@link #createRequestMappingInfo(RequestMapping, RequestCondition)},
	 * supplying the appropriate custom {@link RequestCondition} depending on whether
	 * the supplied {@code annotatedElement} is a class or method.
	 * @see #getCustomTypeCondition(Class)
	 * @see #getCustomMethodCondition(Method)
	 */
	@Nullable
	private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
		// 获得 @RequestMapping 注解
		RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);
		// 获得自定义的条件。目前都是空方法，可以无视
		RequestCondition<?> condition = (element instanceof Class ?
				getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));
		// 基于 @RequestMapping 注解，创建 RequestMappingInfo 对象
		return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
	}

getMappingForMethod方法中调用createRequestMappingInfo方法，完成从类中筛选有RequestMapping注解修饰的方法存储到处理器映射器中

RequestMappingHandlerMapping的registerHandlerMethod

protected void registerHandlerMethod(Object handler, Method method, RequestMappingInfo mapping) {
		super.registerHandlerMethod(handler, method, mapping);
		updateConsumesCondition(mapping, method);
	}

AbstractHandlerMethodMapping的registerHandlerMethod

protected void registerHandlerMethod(Object handler, Method method, T mapping) {
		this.mappingRegistry.register(mapping, handler, method);
	}

AbstractHandlerMethodMapping的register

		/**
		 * 释放读锁
		 *
		 * Release the read lock after using getMappings and getMappingsByUrl.
		 */
		public void releaseReadLock() {
			this.readWriteLock.readLock().unlock();
		}

		public void register(T mapping, Object handler, Method method) {
			// Assert that the handler method is not a suspending one.
			if (KotlinDetector.isKotlinType(method.getDeclaringClass())) {
				Class<?>[] parameterTypes = method.getParameterTypes();
				if ((parameterTypes.length > 0) && "kotlin.coroutines.Continuation".equals(parameterTypes[parameterTypes.length - 1].getName())) {
					throw new IllegalStateException("Unsupported suspending handler method detected: " + method);
				}
			}
			// 获得写锁
			this.readWriteLock.writeLock().lock();
			try {
				// 创建HandlerMethod对象
				HandlerMethod handlerMethod = createHandlerMethod(handler, method);
				// 校验当前mapping是否存在对应的HandlerMethod对象，如果已存在但不是当前的handlerMethod对象则抛出异常
				validateMethodMapping(handlerMethod, mapping);
				// 将mapping与handlerMethod的映射关系保存至this.mappingLookup
				this.mappingLookup.put(mapping, handlerMethod);

				// 获得mapping对应的普通URL数组
				List<String> directUrls = getDirectUrls(mapping);
				// 将url和mapping的映射关系保存至this.urlLookup
				for (String url : directUrls) {
					this.urlLookup.add(url, mapping);
				}

				// 初始化nameLookup
				String name = null;
				if (getNamingStrategy() != null) {
					// 获得Mapping的名字
					name = getNamingStrategy().getName(handlerMethod, mapping);
					// 将mapping的名字与HandlerMethod的映射关系保存至this.nameLookup
					addMappingName(name, handlerMethod);
				}

				// 初始化CorsConfiguration配置对象
				CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping);
				if (corsConfig != null) {
					this.corsLookup.put(handlerMethod, corsConfig);
				}

				// 创建MappingRegistration对象
				// 并与mapping映射添加到registry注册表中
				this.registry.put(mapping, new MappingRegistration<>(mapping, handlerMethod, directUrls, name));
			}
			finally {
				// 释放写锁
				this.readWriteLock.writeLock().unlock();
			}
		}

submit方法对应的FlashMapController存在映射器了，其他@Controller修饰的注解处理过程一样。