如何防止用户名重复？

1. 布隆过滤器将所有用户名加载；

2. 数据库添加唯一索引；

   

大量请求一个未注册用户名？

加锁避免缓存穿透；

private final RedissonClient redissonClient;

// ......

@Override
public void register(UserRegisterReqDTO requestParam) {
    if(!hasUsername(requestParam.getUsername())){
        throw new ClientException(USER_NAME_EXIST);
    }
    RLock lock = redissonClient.getLock(LOCK_USER_REGISTER_KEY+requestParam.getUsername());
    try {
        if(lock.tryLock()){
            // 布隆过滤器误判，捕捉异常
            try {
                // 获得锁 插入数据库
                int inserted = baseMapper.insert(BeanUtil.toBean(requestParam, UserDO.class));
                if(inserted < 1){
                    throw new ClientException(USER_SAVE_ERROR);
                }
            } catch (DuplicateKeyException ex) {
                throw new ClientException(USER_EXIST);
            }
            userRegisterCachePenetrationBloomFilter.add(requestParam.getUsername());
            //todo 设置默认分组
            return ;
        }
        throw new ClientException(USER_NAME_EXIST);
    } finally {
        lock.unlock();
    }
}

修改用户

接口：

@PutMapping("/api/short-link/admin/v1/user")
public Result<Void> update(@RequestBody UserUpdateReqDTO requestParam) {
    userService.update(requestParam);
    return Results.success();
}

@Override
public void update(UserUpdateReqDTO requestParam) {
    // todo 验证当前用户名是否为登录用户
    LambdaUpdateWrapper<UserDO> updateWrapper = Wrappers.lambdaUpdate(UserDO.class)
            .eq(UserDO::getUsername, requestParam.getUsername());
    baseMapper.update(BeanUtil.toBean(requestParam,UserDO.class),updateWrapper);
}