ssm框架里面怎样实现保持在线

实现功能，在登陆状态下浏览器跟服务器一段时间不进行交互，session内部存放的信息将会失效，类似存放在其中的(adminUser)但是依然可以浏览登录后的网页，再跟服务器进行交互才会报错

实现需求：SpringMVC Redis 数据库

1.SpringMVC 进行拦截，

1)session里面有adminUser，则把adminUserId放到redis内部 JedisUtils.setex("keeponline_" + request.getSession().getId(), 60 * 60 * 24, adminUser.getId() + ""); return true;

2)session里面没有adminUser 如果不存在则有可能两种情况，第一次访问服务器或者session过期

　　进一步判断，Cookie sessionIdCookie = WebUtils.getCookie(request, "JSESSIONID");如果sessionIdCookie==null,则说明第一次访问，return true,

　　否则的话从redis里面取出当session里面有数据已经存放在redis里面的adminUserId,对应的key为“keeponline”+sessionIdCookie.getValue(),

　　String oldSessionId = sessionIdCookie.getValue();
　　String adminUserId = JedisUtils.get("keeponline_" + oldSessionId);然后在数据库进行查找，重新把adminUser添加到session里面进行正常操作

3）配置拦截器，登录，退出不需要进行拦截

相关代码：

package com.rupeng.web.rupengInterceptor;

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

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import org.springframework.web.util.WebUtils;

import com.rupeng.pojo.AdminUser;
import com.rupeng.service.AdminUserService;
import com.rupeng.util.JedisUtils;

public class OnlineInterceptor extends HandlerInterceptorAdapter
{
@Autowired
private AdminUserService adminUserService;

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
{
AdminUser adminUser = (AdminUser) request.getSession().getAttribute("adminUser");
//判断adminUser是否为null,不是则继续往下走，是的话有可能第一次打开浏览器，也有可能seession过期，继续判断
if (adminUser == null)
{
Cookie sessionIdCookie = WebUtils.getCookie(request, "JSESSIONID");
if (sessionIdCookie == null)//如果为null则说明第一次访问
{
return true;
}
//不为null则从redis里面把对应的adminUserId取出来，重新设置到session内进行正常操作
//存放到redis时约定主键为keeponline_sessionIdCookie (keeponline_sessionIdCookie,adminUserId)
String oldSessionId = sessionIdCookie.getValue();
String adminUserId = JedisUtils.get("keeponline_" + oldSessionId);
if (adminUserId == null)
{
return true;
}
adminUser = adminUserService.selectOne(Long.parseLong(adminUserId));

request.getSession().setAttribute("adminUser", adminUser);
return true;
}

JedisUtils.setex("keeponline_" + request.getSession().getId(), 60 * 60 * 24, adminUser.getId() + "");
return true;
}

}

<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:mapping path="/subject/*"/>
<mvc:mapping path="/card/*"/>
<mvc:mapping path="/user/*"/>
<mvc:mapping path="/classes/*"/>
<mvc:mapping path="/permission/*"/>
<mvc:mapping path="/*"/>
<mvc:exclude-mapping path="/adminUser/login.do"/>
<mvc:exclude-mapping path="/adminUser/logout.do"/>
<bean class="com.rupeng.web.rupengInterceptor.OnlineInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>