Java Web之限制用户多处登录实例代码

public class LoginUserMap {

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

  /**
   * 将用户和sessionId存入map
   * @param key
   * @param value
   */
  public static void setLoginUsers(String loginId, String sessionId) {
    loginUsers.put(loginId, sessionId);
  }

  /**
   * 获取loginUsers
   * @return
   */
  public static Map<String, String> getLoginUsers() {
    return loginUsers;
  }

  /**
   * 根据sessionId移除map中的值
   * @param sessionId
   */
  public static void removeUser(String sessionId) {
    for (Map.Entry<String, String> entry : loginUsers.entrySet()) {
      if (sessionId.equals(entry.getValue())) {
        loginUsers.remove(entry.getKey());
        break;
      }
    }
  }

  /**
   * 判断用户是否在loginusers中
   * @param loginId
   * @param sessionId
   * @return
   */
  public static boolean isInLoginUsers(String loginId, String sessionId) {
    return (loginUsers.containsKey(loginId) && sessionId.equals(loginUsers.get(loginId)));
  }

}

//登录方法所在的地方
public void login(ttpServletRequest request) {
  try {  
      ......//一系列登录的方法
      HttpSession session = request.getSession();
      LoginUserMap.setLoginUsers(username, session.getId());//保存sessionId到map中
    } catch (LoginException ex) {
      throw ex;
    }
}

public class SessionListener implements HttpSessionListener {
  private Log log = LogFactory.getLog(SessionListener.class);

  /**
   * 创建session时候的动作
   * @param event
   */
  @Override
  public void sessionCreated(HttpSessionEvent event) {

  }

  /**
   * 销毁session时候的动作
   * @param event
   */
  @Override
  public void sessionDestroyed(HttpSessionEvent event) {
    HttpSession session = event.getSession();
    String sessionId = session.getId();
    //移除loginUsers中已经被销毁的session
    LoginUserMap.removeUser(sessionId);
    log.info(sessionId + "被销毁！");
    }
}

  <listener>
    <listener-class>io.github.brightloong.loginlimite.SessionListener</listener-class>
  </listener>

public class LoginLimitFilter implements Filter{

  private Log log = LogFactory.getLog(LoginLimitFilter.class);

  /**
   * 销毁时的方法
   */
  @Override
  public void destroy() {

  }

  /**
   * 过滤请求
   * @param request
   * @param response
   * @param filterChain
   * @throws IOException
   * @throws ServletException
   */
  @Override
  public void doFilter(ServletRequest request, ServletResponse response,
     FilterChain filterChain) throws IOException, ServletException {
    HttpServletRequest servletRequest = (HttpServletRequest) request;
    HttpServletResponse servletResponse = (HttpServletResponse) response;
    HttpSession session = servletRequest.getSession();

    //获取项目路径
    String path = servletRequest.getContextPath(); 
    String basePath = servletRequest.getScheme()+"://"+servletRequest.getServerName()+":"+servletRequest.getServerPort()+path;

    try {
      //获取用户信息，如果没获取到会抛出错误,我的是这样,代表用户还没有登录
      IUser user = UserUtils.getCurrUserInfo();
      String loginId = user.getLoginId();
      //判断当前用户的sessionId是否在loginUsers中，如果没有执行if后的操作
      if(!LoginUserMap.isInLoginUsers(loginId, session.getId())) {
        //当前用户logout
        logout();//自己的logout方法
        //调到登录页面，并表明退出方式为挤下线
        servletResponse.sendRedirect(basePath + "?logoutway=edge");
      }
    } catch (Exception e) {
      log.debug("获取当前用户信息失败，用户未登陆！", e);
    } finally {
      filterChain.doFilter(request, response);
    }
  }

  /**
   * 初始化方法
   * @param arg0
   * @throws ServletException
   */
  @Override
  public void init(FilterConfig arg0) throws ServletException {

  }

}

  <filter>
    <filter-name>LoginLimitFilter</filter-name>
    <filter-class>io.github.brightloong.loginlimite.LoginLimitFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>LoginLimitFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

window.onload = function(){
  if(window.parent != window){
    window.parent.location.href=window.location.href;
  } else {
    if(GetQueryString('logoutway')) {
      //alert('该用户已在其他地方登录，你已下线');
      layer.alert('该账号已在其他地方登录，您已被迫下线，如非本人操作请重新登录并及时修改密码', {
         skin: 'layui-layer-lan', //样式类名
         title: '提示'
         ,closeBtn: 0
        }, function(){
          var url = window.location.href;
          window.location.href = url.substr(0,url.indexOf('?logoutway=edge'));
        });
   }
  }
}

function GetQueryString(name)
{
   var reg = new RegExp("(^|&)"+ name +"=([^&]*)(&|$)");
   var r = window.location.search.substr(1).match(reg);
   if(r!=null)return unescape(r[2]); return null;
}