Java Spring拦截器案例详解

package com.xy.interceptors;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;

/**
* 方法耗时统计拦截器
*/
public class MethodTimerInterceptor implements HandlerInterceptor {

    private static final Logger LOGGER=Logger.getLogger(MethodTimerInterceptor.class);

    //前置功能，  开始到结束，两个点减法
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //定义开始时间
        long start = System.currentTimeMillis();
        //2.将其存到请求域当中
        request.setAttribute("start",start);
        //记录请求日志
        LOGGER.info(request.getRequestURI()+",请求到达");
        //3,返回true，才会找下一个拦截器，如果没有下一个拦截器，则去Controller
        return true;
    }


    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        //1,取出start
        long start = (long) request.getAttribute("start");


        //2,得到end
        long end =System.currentTimeMillis();


        //3,记录耗时
        long spendTime = end-start;
        if (spendTime>2000){
            LOGGER.warn("方法耗时严重，请及时处理，耗时："+spendTime);
        }else {
            LOGGER.info("方法耗时"+spendTime+"毫秒，正常");
        }
    }


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


    }
}

<!--拦截器的配置-->
<mvc:interceptors>
    <mvc:interceptor>
        <!--


        -->
        <mvc:mapping path="/**/*"/>
        <bean class="com.xy.interceptors.MethodTimerInterceptor">


        </bean>
    </mvc:interceptor>
</mvc:interceptors>

package com.xy.interceptors;


import com.xy.pojo.User;
import org.apache.log4j.Logger;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;


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


public class SessionInterceptor implements HandlerInterceptor {


    private static final Logger LOGGER=Logger.getLogger(SessionInterceptor.class);


    //检查当前会话是否有User，如果有则放行，没有则拦截
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Object user = request.getSession().getAttribute("SESSION_USER");


        if (user==null){
            LOGGER.warn("您不具备权限，请先登录");
            return false;
        }


        if(user instanceof User){
            //再去数据库检查其身份对不对，是否冻结。。。
            User user1 = (User) user;
            user1.setPwd(null);
            request.getSession().setAttribute("SESSION_USER",user1);
            LOGGER.info(user1.getName()+"处于登录状态，可以执行操作");
            return true;
        }else {
            LOGGER.warn("请先登录");
            return false;
        }
    }


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


    }


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


    }
}

<!--拦截器的配置-->
<mvc:interceptors>

    <!--只想拦截/user2/**/*
        还需要开放登录权限
    -->
    <mvc:interceptor>
        <mvc:mapping path="/user2/**/*"/>
        <!--排除登录的URI-->
        <mvc:exclude-mapping path="/user2/login"></mvc:exclude-mapping>
        <bean class="com.xy.interceptors.SessionInterceptor"></bean>
    </mvc:interceptor>
</mvc:interceptors>