RedisPoolUtil帮助类参照：https://blog.csdn.net/Richard_666/article/details/103494245

应用场景：

当选择忘记密码的时候，进行问题验证的时候，可以将答案存储在缓存中

1、如项目不是tomcat集群，可以使用GuavaCache，代码如下：

public class TokenCache {

    private static Logger logger = LoggerFactory.getLogger(TokenCache.class);

    public static final String TOKEN_PREFIX = "token_";

    //LRU算法
    private static LoadingCache<String,String> localCache = CacheBuilder.newBuilder().initialCapacity(1000).maximumSize(10000).expireAfterAccess(12, TimeUnit.HOURS)
            .build(new CacheLoader<String, String>() {
                //默认的数据加载实现,当调用get取值的时候,如果key没有对应的值,就调用这个方法进行加载.
                @Override
                public String load(String s) throws Exception {
                    return "null";
                }
            });

    public static void setKey(String key,String value){
        localCache.put(key,value);
    }

    public static String getKey(String key){
        String value = null;
        try {
            value = localCache.get(key);
            if("null".equals(value)){
                return null;
            }
            return value;
        }catch (Exception e){
            logger.error("localCache get error",e);
        }
        return null;
    }
}

2、检验问题答案的逻辑

   public ServerResponse<String> checkAnswer(String username,String question,String answer){
        int resultCount = userMapper.checkAnswer(username,question,answer);
        if(resultCount>0){
            //说明问题及问题答案是这个用户的,并且是正确的
            String forgetToken = UUID.randomUUID().toString();
            TokenCache.setKey(TokenCache.TOKEN_PREFIX+username,forgetToken);
            return ServerResponse.createBySuccess(forgetToken);
        }
        return ServerResponse.createByErrorMessage("问题的答案错误");
    }

    public ServerResponse<String> forgetResetPassword(String username,String passwordNew,String forgetToken){
        if(org.apache.commons.lang3.StringUtils.isBlank(forgetToken)){
            return ServerResponse.createByErrorMessage("参数错误,token需要传递");
        }
        ServerResponse validResponse = this.checkValid(username,Const.USERNAME);
        if(validResponse.isSuccess()){
            //用户不存在
            return ServerResponse.createByErrorMessage("用户不存在");
        }
        String token = TokenCache.getKey(TokenCache.TOKEN_PREFIX+username);
        if(org.apache.commons.lang3.StringUtils.isBlank(token)){
            return ServerResponse.createByErrorMessage("token无效或者过期");
        }

        if(org.apache.commons.lang3.StringUtils.equals(forgetToken,token)){
            String md5Password  = MD5Util.MD5EncodeUtf8(passwordNew);
            int rowCount = userMapper.updatePasswordByUsername(username,md5Password);

            if(rowCount > 0){
                return ServerResponse.createBySuccessMessage("修改密码成功");
            }
        }else{
            return ServerResponse.createByErrorMessage("token错误,请重新获取重置密码的token");
        }
        return ServerResponse.createByErrorMessage("修改密码失败");
    }

修改为redis存储，更改后可以将TokenCache这个类删除掉

    public ServerResponse<String> checkAnswer(String username,String question,String answer){
        int resultCount = userMapper.checkAnswer(username,question,answer);
        if(resultCount>0){
            //说明问题及问题答案是这个用户的,并且是正确的
            String forgetToken = UUID.randomUUID().toString();
           
            RedisPoolUtil.setEx(TokenCache.Token_PREFIX+username,forgetToken,60*60*12);

            return ServerResponse.createBySuccess(forgetToken);
        }
        return ServerResponse.createByErrorMessage("问题的答案错误");
    }