SpringMVC -- 拦截器

一.拦截器

定义拦截器，实现HandlerInterceptor接口

package com.huan.web;

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{

    //进入Handler方法之前执行
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        //return false表示拦截，不向下执行
        //return true表示放行
        return false;
    }

    //进入Handler方法之后，返回modelAndView之前执行
    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

    }

    //执行Handle之后执行
    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
    }
}

可以从名称和参数看出各个接口的顺序和作用:

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception

参数最少，只有三个
进入 Handler方法之前执行
用于身份认证、身份授权。比如身份认证，如果认证通过表示当前用户没有登陆，需要此方法拦截不再向下执行

public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, 
ModelAndView modelAndView) throws Exception

多了一个modelAndView参数
进入Handler方法之后，返回modelAndView之前执行
应用场景从modelAndView出发：将公用的模型数据(比如菜单导航)在这里传到视图，也可以在这里统一指定视图

public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, 
Exception ex) throws Exception

多了一个Exception的类型的参数
执行Handler完成执行此方法
应用场景：统一异常处理，统一日志处理

二.拦截器配置

针对HandlerMapping配置

springmvc拦截器针对HandlerMapping进行拦截设置，如果在某个HandlerMapping中配置拦截，经过该HandlerMapping映射成功的handler最终使用该拦截器。

不推荐使用

类似全局的拦截器

springmvc配置类似全局的拦截器，springmvc框架将配置的类似全局的拦截器注入到每个HandlerMapping中。

三.多拦截器测试

拦截器一:Interceptor1.java

package com.huan.web.Interceptor1;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Interceptor1 implements HandlerInterceptor{

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("拦截器一执行------preHandle");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("拦截器一执行-------postHandle");
    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("拦截器一执行------afterCompletion");
    }
}

拦截器二：Interceptor2.java

package com.huan.web.Interceptor1;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Interceptor2 implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("拦截器二执行------preHandle");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("拦截器二执行-------postHandle");

    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("拦截器二执行------afterCompletion");

    }
}