SpringMVC源码-@ControllerAdvice和 @InitBinder注解源码讲解

1.@ControllerAdvice修饰的类何时被加载扫描

被@ControllerAdvice修饰的类是作用于全局的

initStrategies 初始化springmvc的9大组件

java 复制代码

initStrategies:531, 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, 1659438018 (sun.rmi.transport.tcp.TCPTransport$ConnectionHandler$$Lambda$24)
doPrivileged:-1, AccessController (java.security)
run:682, TCPTransport$ConnectionHandler (sun.rmi.transport.tcp)
runWorker:1142, ThreadPoolExecutor (java.util.concurrent)
run:617, ThreadPoolExecutor$Worker (java.util.concurrent)
run:748, Thread (java.lang)

initHandlerAdapters(context); 初始化 HandlerAdapter:处理适配器，主要包含Http请求处理器适配器，简单控制器处理器适配器，注解方法处理器适配器

循环遍历生成，遍历到RequestMappingHandlerAdapter，类图如下:

因为实现了InitializingBean接口，当初始化调用afterPropertiesSet方法:

initControllerAdviceCache 初始化注释了@ControllerAdvice的类的相关属性

java 复制代码

	private void initControllerAdviceCache() {
		// 判断当前应用程序上下文是否为空，如果为空，直接返回
		if (getApplicationContext() == null) {
			return;
		}

		// 扫描@ControllerAdvice注解的Bean，生成对应的ControllerAdviceBean对象，并将进行排序
		List<ControllerAdviceBean> adviceBeans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());

		List<Object> requestResponseBodyAdviceBeans = new ArrayList<>();

		// 遍历ControllerAdviceBean数组
		for (ControllerAdviceBean adviceBean : adviceBeans) {
			Class<?> beanType = adviceBean.getBeanType();
			if (beanType == null) {
				throw new IllegalStateException("Unresolvable type for ControllerAdviceBean: " + adviceBean);
			}
			// 扫描有`@ModelAttribute`，无`@RequestMapping`注解的方法，添加到`modelAttributeAdviceCache`属性中
			// 该类方法用于在执行方法前修改 Model 对象
			Set<Method> attrMethods = MethodIntrospector.selectMethods(beanType, MODEL_ATTRIBUTE_METHODS);
			if (!attrMethods.isEmpty()) {
				this.modelAttributeAdviceCache.put(adviceBean, attrMethods);
			}
			// 扫描有`@InitBinder`注解的方法，添加到`initBinderAdviceCache`属性中
			// 该类方法用于在执行方法前初始化数据绑定器
			Set<Method> binderMethods = MethodIntrospector.selectMethods(beanType, INIT_BINDER_METHODS);
			if (!binderMethods.isEmpty()) {
				this.initBinderAdviceCache.put(adviceBean, binderMethods);
			}
			// 如果是RequestBodyAdvice或ResponseBodyAdvice的子类，添加到requestResponseBodyAdviceBeans中
			if (RequestBodyAdvice.class.isAssignableFrom(beanType) || ResponseBodyAdvice.class.isAssignableFrom(beanType)) {
				requestResponseBodyAdviceBeans.add(adviceBean);
			}
		}

		// 将requestResponseBodyAdviceBeans添加到this.requestResponseBodyAdvice属性中
		if (!requestResponseBodyAdviceBeans.isEmpty()) {
			this.requestResponseBodyAdvice.addAll(0, requestResponseBodyAdviceBeans);
		}

		// 打印日志
		if (logger.isDebugEnabled()) {
			int modelSize = this.modelAttributeAdviceCache.size();
			int binderSize = this.initBinderAdviceCache.size();
			int reqCount = getBodyAdviceCount(RequestBodyAdvice.class);
			int resCount = getBodyAdviceCount(ResponseBodyAdvice.class);
			if (modelSize == 0 && binderSize == 0 && reqCount == 0 && resCount == 0) {
				logger.debug("ControllerAdvice beans: none");
			}
			else {
				logger.debug("ControllerAdvice beans: " + modelSize + " @ModelAttribute, " + binderSize +
						" @InitBinder, " + reqCount + " RequestBodyAdvice, " + resCount + " ResponseBodyAdvice");
			}
		}
	}

List adviceBeans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());

java 复制代码

	/**在给定的{@link ApplicationContext}中找到带有{@link ControllerAdvice @ControllerAdvice}注释的bean
	 * Find beans annotated with {@link ControllerAdvice @ControllerAdvice} in the
	 * given {@link ApplicationContext} and wrap them as {@code ControllerAdviceBean}
	 * instances.并将它们包装为{@code ControllerAdviceBean}实例。
	 * <p>As of Spring Framework 5.2, the {@code ControllerAdviceBean} instances
	 * in the returned list are sorted using {@link OrderComparator#sort(List)}. ，<p>从Spring Framework 5.2开始，返回列表中的{@code ControllerAdviceBean}实例使用{@link OrderComparatorsort(list)}进行排序。
	 * @see #getOrder() 
	 * @see OrderComparator
	 * @see Ordered
	 */
	public static List<ControllerAdviceBean> findAnnotatedBeans(ApplicationContext context) {
		List<ControllerAdviceBean> adviceBeans = new ArrayList<>();
		for (String name : BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context, Object.class)) {
			if (!ScopedProxyUtils.isScopedTarget(name)) {
				ControllerAdvice controllerAdvice = context.findAnnotationOnBean(name, ControllerAdvice.class);
				if (controllerAdvice != null) {
					// Use the @ControllerAdvice annotation found by findAnnotationOnBean()
					// in order to avoid a subsequent lookup of the same annotation.
					adviceBeans.add(new ControllerAdviceBean(name, context, controllerAdvice));
				}
			}
		}
		OrderComparator.sort(adviceBeans);
		return adviceBeans;
	}

该类在这里会被扫描识别类下的方法:

ControllerAdviceController该类会被识别到，结果如下:

和上面注解修饰的方法对应。