1.2XX 成功
200 ok
204 No Content
206 Partial Content
2.3XX 重定向
301 Moved Permanently
302 Found
303 See Other
304 Not Modified
307 Temporary Redirect
3.4XX 客户端错误
400 Bad Request
401 Unauthorized
403 Forbidden
404 Not Found
4.5XX 服务器错误
500 Internal Server Error
503 Service Unavailable
