HandlerExecutionChain类比较简单，好理解。
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/* * 处理器执行链由处理器对象和拦截器组成。 */public class HandlerExecutionChain { |
下面是类的部分属性。
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private final Object handler; //处理器对象。 private HandlerInterceptor[] interceptors; //拦截器数组 private List<HandlerInterceptor> interceptorList; //拦截器列表 |
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/** * Apply preHandle methods of registered interceptors. * @return {@code true} if the execution chain should proceed with the * next interceptor or the handler itself. Else, DispatcherServlet assumes * that this interceptor has already dealt with the response itself. * 执行已经注册的拦截的 preHandle()方法。如果返回true,则执行链可以执行下一个拦截器的preHandle()方法或 handler 自身。 * 否则， */ boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception { HandlerInterceptor[] interceptors = getInterceptors(); if (!ObjectUtils.isEmpty(interceptors)) { for (int i = 0; i < interceptors.length; i++) { HandlerInterceptor interceptor = interceptors[i]; if (!interceptor.preHandle(request, response, this.handler)) { triggerAfterCompletion(request, response, null); return false; } this.interceptorIndex = i; } } return true; } |
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/* * 执行已经注册的拦截器 postHandle()方法。 */ void applyPostHandle(HttpServletRequest request, HttpServletResponse response, ModelAndView mv) throws Exception { HandlerInterceptor[] interceptors = getInterceptors(); if (!ObjectUtils.isEmpty(interceptors)) { for (int i = interceptors.length - 1; i >= 0; i--) { HandlerInterceptor interceptor = interceptors[i]; interceptor.postHandle(request, response, this.handler, mv); } } } |
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/** * 这个方法只会执行preHandle()方法已经成功执行并且返回true的拦截器中的postHandle()方法。 */ void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, Exception ex) throws Exception { HandlerInterceptor[] interceptors = getInterceptors(); if (!ObjectUtils.isEmpty(interceptors)) { for (int i = this.interceptorIndex; i >= 0; i--) { HandlerInterceptor interceptor = interceptors[i]; try { interceptor.afterCompletion(request, response, this.handler, ex); } catch (Throwable ex2) { logger.error("HandlerInterceptor.afterCompletion threw exception", ex2); } } } } |
以上这篇对handlerexecutionchain类的深入理解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持服务器之家。
