AOP实现的动态代理中的包括 方法拦截器数组，DispatcherServlet包括的是处理器拦截器。
DispatcherServlet 初始化时调用 onRefresh 方法，调用 initStrategies() 的this.initHandlerMappings(context); 方法中加载拦截器。
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protected void onRefresh(ApplicationContext context) {
this.initStrategies(context);
}
protected void initStrategies(ApplicationContext context) {
this.initMultipartResolver(context);
this.initLocaleResolver(context);
this.initThemeResolver(context);
this.initHandlerMappings(context);
this.initHandlerAdapters(context);
this.initHandlerExceptionResolvers(context);
this.initRequestToViewNameTranslator(context);
this.initViewResolvers(context);
this.initFlashMapManager(context);
}
initHandlerMappings() 方法会加载所有实现 HandlerMappin 的类。
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private void initHandlerMappings(ApplicationContext context) {
this.handlerMappings = null;
if (this.detectAllHandlerMappings) {
Map<String, HandlerMapping> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
if (!matchingBeans.isEmpty()) {
this.handlerMappings = new ArrayList(matchingBeans.values());
AnnotationAwareOrderComparator.sort(this.handlerMappings);
}
} else {
try {
HandlerMapping hm = (HandlerMapping)context.getBean("handlerMapping", HandlerMapping.class);
this.handlerMappings = Collections.singletonList(hm);
} catch (NoSuchBeanDefinitionException var3) {
;
}
}
在doDispatch方法中，mappedHandler = this.getHandler(processedRequest); 实际是调用抽象类AbstractHandlerMapping 的public final HandlerExecutionChain getHandler(HttpServletRequest request)方法，获取了一个HandlerExecutionChain对象,把匹配request的url的拦截器都加入HandlerExecutionChain。
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protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
HandlerExecutionChain chain = handler instanceof HandlerExecutionChain ? (HandlerExecutionChain)handler : new HandlerExecutionChain(handler);
String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);
Iterator var5 = this.adaptedInterceptors.iterator();
while(var5.hasNext()) {
HandlerInterceptor interceptor = (HandlerInterceptor)var5.next();
if (interceptor instanceof MappedInterceptor) {
MappedInterceptor mappedInterceptor = (MappedInterceptor)interceptor;
if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
chain.addInterceptor(mappedInterceptor.getInterceptor());
}
} else {
chain.addInterceptor(interceptor);
}
}
拦截器执行
拦截器的 preHandle 方法是在 HandlerExecutionChain 对象的 applyPreHandle方法中被调用，这个调用是在 HandlerAdapter 对象的 handle 方法也就是 contrller 本身的方法调用之前。postHandle 在之后，最后在 processDispatchResult 处理返回结果和抓异常时执行拦截器的 afterCompletion 方法。
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boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
HandlerInterceptor[] interceptors = this.getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for(int i = 0; i < interceptors.length; this.interceptorIndex = i++) {
HandlerInterceptor interceptor = interceptors[i];
if (!interceptor.preHandle(request, response, this.handler)) {
this.triggerAfterCompletion(request, response, (Exception)null);
return false;
}
}
}
return true;
}
