springmvc之配置拦截器拦截相应的请求

在springmvc.xml文件中配置：

    <mvc:interceptors>
        <!-- 配置自定义的拦截器 -->
        <bean class="com.gong.springmvc.interceptors.FirstInterceptor"></bean>
        <mvc:interceptor>
            <mvc:mapping path="/emps"/>
            <bean class="com.gong.springmvc.interceptors.SecondInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>

FirstInterceptor.java

package com.gong.springmvc.interceptors;

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

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

public class FirstInterceptor implements HandlerInterceptor{
    
    //该方法在目标方法之前被调用
    //如果返回true，则继续调用后续的拦截器和目标方法，若为false，则不会在调用后续的拦截器和目标方法
    //该方法可以考虑做权限、日志、事务等
    @Override
    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        System.out.println("[FirstInterceptor] preHandle");
        return true;
    }
    
    //调用目标方法之后，但在渲染视图之前被调用
    //可以修改请求域中的属性或视图做出修改
    @Override
    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("[FirstInterceptor] postHandle");
    }

    //在渲染视图之后被调用
    //释放资源
    @Override
    public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("[FirstInterceptor] afterCompletion");
    }

}

SecondInceptor.java

package com.gong.springmvc.interceptors;

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

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

public class SecondInterceptor implements HandlerInterceptor{

    @Override
    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        System.out.println("[SecondInterceptor] preHandle");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("[SecondInterceptor] postHandle");
    }

    @Override
    public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("[SecondInterceptor] afterCompletion");
    }

}

在<mvc:mapping path="/emps"/>中可以配置拦截的url地址。

在<mvc:exclude-mapping path=""/>中可以配置不拦截的url地址。

像这种定义在<mvc:interceptors>下的<bean class="com.gong.springmvc.interceptors.FirstInterceptor"></bean>，没有指定是否拦截，则默认所有请求都调用该拦截器。

在<mvc:interceptor>下使用<mvc:mapping path="/emps"/>表明要拦截该地址，调用的拦截器是SecondInterceptor。

比如说，我们如果请求地址是/emps，那么两个拦截器都会被调用，在控制台可以看到：

如果请求地址不是/emps，那么只会调用FirstInterceptor拦截器：