SpringMVC：拦截器

一般我们会做一些统一的操作这个时候我们需要使用springmvc提供的拦截器，例如token的验证，字段必填的操作，接口超时判断，签名验证，字段加密等操作，所以我们需要了解执行先后顺序。我们来简单介绍下实现过程及对应代码，执行结果：

1、定义自己的spring mvc拦截器需要实现HandlerInterceptor 接口或者继承HandlerInterceptorAdapter

2、boolean preHandle()方法在controller被调用之前调用；

3、void postHandle()方法在controller被调用之后调用，可在modelandview中加入数据，比如当前时间；

4、void afterCompletion()在呈现视图之后调用，可用于清理资源等；

5、当设置多个拦截器时，先按顺序调用preHandle方法，然后逆序调用每个拦截器的postHandle和afterCompletion方法

public class MyInterceptor1 extends HandlerInterceptorAdapter {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("-------preHandle1-------");// 如果返回false，则不再调用之后的方法  return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("-------postHandle1-------");if (modelAndView != null) { // 当前时间  modelAndView.addObject("now", new Date());}}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("-------afterCompletion1-------");}}

 public class MyInterceptor2 extends HandlerInterceptorAdapter {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("-------preHandle2-------");// 如果返回false，则不再调用之后的方法  return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("-------postHandle2-------");if (modelAndView != null) { // 加入当前时间  modelAndView.addObject("now", new Date());}}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("-------afterCompletion2-------");}}

<mvc:interceptors><mvc:interceptor><mvc:mapping path="/**"/><bean class="com.kingbal.web.interceptor.MyInterceptor1" /></mvc:interceptor><mvc:interceptor><mvc:mapping path="/**"/><bean class="com.kingbal.web.interceptor.MyInterceptor2" /></mvc:interceptor>
</mvc:interceptors>

会根据配置先后顺序往下执行，执行结果如下图 >>