本例实现登陆时的验证拦截，采用SpringMVC拦截器来实现

核心代码

首先是index.jsp,显示链接

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

首页

controller类

package com.jikexueyuan.demo.springmvc.lesson4.controller;

import javax.annotation.Resource;

import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RequestParam;

import com.jikexueyuan.demo.springmvc.lesson4.constant.Global;

import com.jikexueyuan.demo.springmvc.lesson4.exception.MyException;

import com.jikexueyuan.demo.springmvc.lesson4.model.User;

import com.jikexueyuan.demo.springmvc.lesson4.service.LoginService;

/**

* 这个例子讲解了如何定义MVC三层注解，使用@Resource进行注入，以及使用@RequestMapping、@RequestParam 、@SessionAttributes

*/

@Controller

public class LoginController extends BaseController {

@Resource

LoginService service;

@Resource

HttpServletRequest request;

@RequestMapping("/exception")

public void exception() throws MyException{

throw new MyException("测试springmvc中的异常捕获");

}

@RequestMapping("/loginpage")

public String toLoginPage(){

return "/WEB-INF/jsp/login.jsp";

}

@RequestMapping("/user/home")

public String toUserHome(){

return "/WEB-INF/jsp/userhome.jsp";

}

@RequestMapping("/logout")

public String logout(){

request.getSession().removeAttribute(Global.USER_SESSION_KEY);

return "redirect:/";

}

@RequestMapping(value = "/doLogin", method = RequestMethod.POST)

public String doLogin(@RequestParam String userName, @RequestParam String password){

try {

User user = service.doLogin(userName, password);

request.getSession().setAttribute(Global.USER_SESSION_KEY, user);

return "redirect:/user/home.html";

} catch (Exception e) {

return "/WEB-INF/jsp/login.jsp";

}

}

}

当点击用户中心时，触发拦截，相关配置如下

在spring-mvc.xml中加上拦截配置，拦截所有URL中包含/user/的请求，当然请求用户中心时就会触发这个拦截器了

然后是bean指向的具体的interceptor类，如果session保存的用户信息为null，则跳到login页面，postHandle和afterCompletion方法都不执行，反之都执行

package com.jikexueyuan.demo.springmvc.lesson4.interceptor;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.HandlerInterceptor;

import org.springframework.web.servlet.ModelAndView;

import com.jikexueyuan.demo.springmvc.lesson4.constant.Global;

public class LoginInterceptor implements HandlerInterceptor {

@Override

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

Object user = request.getSession().getAttribute(Global.USER_SESSION_KEY);

if (user == null) {

System.out.println("尚未登录，调到登录页面");

response.sendRedirect("/loginpage.html");

return false;

}

return true;

}

@Override

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

System.out.println("postHandle");

}

@Override

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

System.out.println("afterCompletion");

}

}

至此，简单的springmvc拦截器就完成了。