拦截器的介绍

那么拦截器Inteceptinon中是如何实现拦截的呢

其实主要还是上面说的首先在Inteception链中增加多个拦截器（也就是上面的addInterceptions方法过滤的多个Intecepter）然后去执行三个方法

1、preHandle(controler执行前执行，返回false标示后面的拦截器不用再执行，已经执行完毕)

2、postHandle（controler执行后，modelView渲染前）

3、aftercomlication（modelView渲染后主要作用是清理资源）

package com.ryc.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class Interceptor  implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("        1在请求之前，  被执行");

        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
            System.out.println("    1在完成业务之后 ，试图解析之前 执行");
    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
            System.out.println("    1再完成视图解析之后");
    }
}

以及 xml 配置：

<mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/*"/>
            <bean id="" class="com.ryc.interceptor."
        </mvc:interceptor>
    </mvc:interceptors>

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