[Java知识库]统一管理session

老项目ssh 要限制用户做唯一登录，比如在谷歌浏览器登录之后，然后再用IE登录，那么谷歌 上的用户就会失效，项目用的session。所以记录一下如何管理，接下来演示代码以springboot的使用测试，原理一样。主要以session监听器做处理操作。

项目的权限校验使用拦截器做处理

@Component
public class LoginIntecptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
        User user = (User)request.getSession().getAttribute("user");
        if(user==null){
            response.sendRedirect("/toLogin");
            return false;
        }
        return true;
    }
}

让拦截器生效

@Configuration
public class MvcConfig implements WebMvcConfigurer {

    @Autowired
    LoginIntecptor loginIntecptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginIntecptor).addPathPatterns("/**").excludePathPatterns("/login","/toLogin");
    }
}

定义session容器

import javax.servlet.http.HttpSession;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class MySessionContext {
        private static MySessionContext instance;  
        private Map<String,HttpSession> sessionMap;
      
        private MySessionContext() {  
            sessionMap = new ConcurrentHashMap<String,HttpSession>();
        }  
      
        public static MySessionContext getInstance() {  
            if (instance == null) {  
                instance = new MySessionContext();  
            }  
            return instance;  
        }  
      
        public synchronized void addSession(HttpSession session) {  
            if (session != null) {  
                sessionMap.put(session.getId(), session);  
            }  
        }


        public synchronized void delSession(HttpSession session) {
            //session过期或者手动设置无效的时候手动移除key
            UserContext.removeKeyByValue(session.getId());
            if (session != null) {  
                sessionMap.remove(session.getId());  
            }  
        }  
      
        public synchronized HttpSession getSession(String sessionID) {  
            if (sessionID == null) {  
                return null;  
            }  
            return sessionMap.get(sessionID);  
        }
}

session监听器

import org.springframework.stereotype.Component;

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

@Component
public class SessionListener implements HttpSessionListener {

    private MySessionContext myc = MySessionContext.getInstance();

    /**
     * 添加session
     * @param e
     */
    @Override
    public void sessionCreated(HttpSessionEvent e) {
        System.out.println("监听到 session 创建, sessionid 是： " + e.getSession().getId());
        myc.addSession(e.getSession());
    }

    /**
     * 移除session
     * @param e
     */
    @Override
    public void sessionDestroyed(HttpSessionEvent e) {
        System.out.println("监听到 session 销毁, sessionid 是： " + e.getSession().getId());
        myc.delSession(e.getSession());
    }
}

用户和session对应关系容器

import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

public class UserContext {

    private static Map<Integer,String> userMap = new ConcurrentHashMap<>();

    /**
     * 存入
     * @param userId
     * @param sessionId
     */
    public static void put(Integer userId,String sessionId){
        userMap.put(userId,sessionId);
    }

    /**
     * 获取
     * @param userId
     * @return
     */
    public static String get(Integer userId){
        return userMap.get(userId);
    }

    /**
     * 移除key
     * @param userId
     */
    public static void remove(Integer userId){
         userMap.remove(userId);
    }

    /**
     * 根据value移除key
     * @param value
     */
    public static void removeKeyByValue(String value){
        Set<Integer> keys = userMap.keySet();
        for(Integer userId: keys){
            String s = userMap.get(userId);
            if(s.equals(value)){
                userMap.remove(userId);
            }
        }
    }
}

测试代码

@GetMapping("/toLogin")
public ModelAndView loginPage(){
  return new ModelAndView("login");
}

@GetMapping("/success")
public ModelAndView success(){
  return new ModelAndView("success");
}

@GetMapping("/login")
public void login(User user, HttpServletRequest request, HttpServletResponse response, HttpSession session) throws IOException {
  if(user==null){
      response.sendRedirect("toLogin");
  }
  String sessionId = UserContext.get(user.getId());
  if(!StringUtils.isEmpty(sessionId)){//说明用户已经登录了
      HttpSession session1 = MySessionContext.getInstance().getSession(sessionId);//移除原来的
      session1.invalidate();
  }
  UserContext.put(user.getId(),session.getId());//重新覆盖
  request.getSession().setAttribute("user",user);
  response.sendRedirect("success");
}

@GetMapping("/logout")
public void logout(HttpServletRequest request, HttpServletResponse response) throws IOException {
  request.getSession().invalidate();
  //return new ModelAndView("login");
  response.sendRedirect("toLogin");
}

效果就不给你们提供了，随便看看就行了，代码也比较简单，了解即可。

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