Springmvc中拦截器的配置

本文应用场景为：
登陆页面有一提交表单的动作。需要在controller中处理。判断用户名密码是否正确。如果正确，向session中写入用户信息。返回登陆成功。
拦截用户请求，判断用户是否登陆。如果用户已经登陆。放行， 如果用户未登陆，跳转到登陆页面

1.在Springmvc的配置文件中注册拦截器

<!--关于拦截器的配置-->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <bean id="loginInterceptor" class="com.yong.interceptor.MyInterceptor"/>
		//com.yong.interceptor.MyInterceptor为存放拦截器文件的路径
        </mvc:interceptor>
    </mvc:interceptors>

2.编写用户登录拦截器

package com.yong.interceptor;

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

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

public class MyInterceptor implements HandlerInterceptor {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        // 如果是登陆页面则放行
        System.out.println("uri: " + request.getRequestURI());
        if (request.getRequestURI().contains("login")) {
            return true;
        }
        HttpSession session = request.getSession();
        // 如果用户已登陆也放行
        if(session.getAttribute("user") != null) {
            return true;
        }
        // 用户没有登陆跳转到登陆页面
        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
        return false;
    }

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

    }

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

    }
}