java使用token防止用户重复登录以及验证用户登录

登录成功后，使用用户id构造生成一个token并保存到redis中，同时也保存用户id到session中

生成token的代码如下：

    @Overridepublic String createToken(String phone,String appId) throws Exception {long loginTime = DateUtil.getNowTimeStampTime().getTime();String str = String.valueOf(phone) + CommonConstant.COMMA_CHARACTER+appId+ CommonConstant.COMMA_CHARACTER+ String.valueOf(loginTime);byte[] cipherData = null;String result = null;cipherData = RSAEncrypt.encrypt(Rsa2Manager.getPublicKeyGmall(), str.getBytes("UTF-8"));//RSA加密result = Base64.encode(cipherData);//加密return result;}

checkToken，获取当前session，有效则已登录，无效则获取当前的token，解密token，再去查询redis中的token是否有效，有效则再次对session赋值，还原登录状态

@Overridepublic boolean isLogin(HttpSession session) throws Exception {boolean islogin = false;String appId = (String) session.getAttribute(UserConstant.LOGIN_APP_ID);String userId = (String) session.getAttribute(UserConstant.USER_SESSION_KEY);if (StringUtils.isNotBlank(appId) && StringUtils.isNotBlank(userId)) {islogin = true;} else {String phone ="";String appid ="";HttpServletRequest request = getCurrentThreadRequest();String currentToken = request.getHeader(CommonConstant.REQUEST_HEADER_TOKEN_NAME);if(StringUtils.isNotBlank(currentToken)){byte[] res = null;res = RSAEncrypt.decrypt(Rsa2Manager.getPrivateKeyGmall(), Base64.decode(currentToken));String restr = new String(res);String[] str = restr.split(",");phone = str[0];appid = str[1];String redisKey = CommonConstant.LOGIN_TOKEN.concat(phone);String token = RedisUtil.getRedisString(redisKey);if (StringUtils.isNotBlank(token)) {request.getSession().setAttribute(UserConstant.USER_SESSION_KEY, phone);request.getSession().setAttribute(UserConstant.LOGIN_APP_ID, appid);islogin = true;}else{islogin = false;}}}return islogin;}