Spring mvc 实现用户登录的方法(拦截器)

package cn.woniubushiniu.controller;

import cn.woniubushiniu.po.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.http.HttpSession;

@Controller
public class UserController {
  /**
   * 向用户登录页面跳转
   */
  @RequestMapping(value = "/login",method = RequestMethod.GET)
  public String toLogin(){
    return "login";
  }

  /**
   * 用户登录
   * @param user
   * @param model
   * @param session
   * @return
   */
  @RequestMapping(value = "/login",method = RequestMethod.POST)
  public String login(User user, Model model, HttpSession session){
    //获取用户名和密码
    String username=user.getUsername();
    String password=user.getPassword();
    //些处横板从数据库中获取对用户名和密码后进行判断
    if(username!=null&&username.equals("admin")&&password!=null&&password.equals("admin")){
      //将用户对象添加到Session中
      session.setAttribute("USER_SESSION",user);
      //重定向到主页面的跳转方法
      return "redirect:main";
    }
    model.addAttribute("msg","用户名或密码错误，请重新登录！");
    return "login";
  }

  @RequestMapping(value = "/main")
  public String toMain(){
    return "main";
  }
  
  @RequestMapping(value = "/logout")
  public String logout(HttpSession session){
    //清除session
    session.invalidate();
    //重定向到登录页面的跳转方法
    return "redirect:login";
  }
  
}

public class LoginInterceptor implements HandlerInterceptor {

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {
    //获取请求的RUi:去除http:localhost:8080这部分剩下的
    String uri = request.getRequestURI();
    //UTL:除了login.jsp是可以公开访问的，其他的URL都进行拦截控制
    if (uri.indexOf("/login") >= 0) {
      return true;
    }
    //获取session
    HttpSession session = request.getSession();
    User user = (User) session.getAttribute("USER_SESSION");
    //判断session中是否有用户数据，如果有，则返回true，继续向下执行
    if (user != null) {
      return true;
    }
    //不符合条件的给出提示信息，并转发到登录页面
    request.setAttribute("msg", "您还没有登录，请先登录！");
    request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
    return false;
  }

  @Override
  public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

  }

  @Override
  public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

  }
}

<!--登录拦截器-->
    <mvc:interceptor>
      <mvc:mapping path="/**"/>
      <bean class="cn.woniubushiniu.interceptor.LoginInterceptor"/>
    </mvc:interceptor>
  </mvc:interceptors>

<!--配置前端控制器-->
  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc-config.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>