springMVC系列源码之请求处理过程――12 - JAVA

; CollectionUtils.mergeArrayIntoCollection(interceptors, this.interceptorList); } else { this.handler = handler; this.interceptors = interceptors; } } public Object getHandler() { return this.handler; } public void addInterceptor(HandlerInterceptor interceptor) { initInterceptorList(); this.interceptorList.add(interceptor); } public void addInterceptors(HandlerInterceptor[] interceptors) { if (interceptors != null) { initInterceptorList(); this.interceptorList.addAll(Arrays.asList(interceptors)); } } private void initInterceptorList() { if (this.interceptorList == null) { this.interceptorList = new ArrayList (); } if (this.interceptors != null) { this.interceptorList.addAll(Arrays.asList(this.interceptors)); this.interceptors = null; } } public HandlerInterceptor[] getInterceptors() { if (this.interceptors == null && this.interceptorList != null) { this.interceptors = this.interceptorList.toArray(new HandlerInterceptor[this.interceptorList.size()]); } return this.interceptors; } boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception { if (getInterceptors() != null) { for (int i = 0; i < getInterceptors().length; i++) { HandlerInterceptor interceptor = getInterceptors()[i]; if (!interceptor.preHandle(request, response, this.handler)) { triggerAfterCompletion(request, response, null); return false; } this.interceptorIndex = i; } } return true; } void applyPostHandle(HttpServletRequest request, HttpServletResponse response, ModelAndView mv) throws Exception { if (getInterceptors() == null) { return; } for (int i = getInterceptors().length - 1; i >= 0; i--) { HandlerInterceptor interceptor = getInterceptors()[i]; interceptor.postHandle(request, response, this.handler, mv); } } void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, Exception ex) throws Exception { if (getInterceptors() == null) { return; } for (int i = this.interceptorIndex; i >= 0; i--) { HandlerInterceptor interceptor = getInterceptors()[i]; try { interceptor.afterCompletion(request, response, this.handler, ex); } catch (Throwable ex2) { logger.error("HandlerInterceptor.afterCompletion threw exception", ex2); } } } void applyAfterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response) { if (getInterceptors() == null) { return; } for (int i = getInterceptors().length - 1; i >= 0; i--) { if (interceptors[i] instanceof AsyncHandlerInterceptor) { try { AsyncHandlerInterceptor asyncInterceptor = (AsyncHandlerInterceptor) this.interceptors[i]; asyncInterceptor.afterConcurrentHandlingStarted(request, response, this.handler); } catch (Throwable ex) { logger.error("Interceptor [" + interceptors[i] + "] failed in afterConcurrentHandlingStarted", ex); } } } } @Override public String toString() { if (this.handler == null) { return "HandlerExecutionChain with no handler"; } StringBuilder sb = new StringBuilder(); sb.append("HandlerExecutionChain with handler [").append(this.handler).append("]"); if (!CollectionUtils.isEmpty(this.interceptorList)) { sb.append(" and ").append(this.interceptorList.size()).append(" interceptor"); if (this.interceptorList.size() > 1) { sb.append("s"); } } return sb.toString(); } }

一个拦截器列表，一个执行对象，这个类的内容十分的简单，它蕴含的设计思想，却十分的丰富。
a） .拦截器组成的列表，在执行对象被调用的前后，会依次执行。这里可以看成是一个的AOP环绕通知，拦截器可以对处理对象随心所欲的进行处理和增强。这里明显是吸收了Struts2中拦截器的设计思想。这种AOP环绕式的扩展点设计，也几乎成为所有框架必备的内容。
b） .实际的处理对象，即handler对象，是由Object对象来引用的。 private final Object handler;之所以要用一个java世界最基础的Object对象引用来引用这个handler对象，是因为连特定的接口也不希望绑定在这个handler对象上，从而使handler对象具有最大程度的选择性和灵活性。

2.3.2 实际执行handler ： mv =ha.handle(processedRequest, response, mappedHandler.getHandler());

有兴趣的可以自己跟一下。处理到最后返回ModelAndView的类：RequestMappingHandlerAdapter）――

	private ModelAndView getModelAnd

springMVC系列源码之请求处理过程――12(五)