Status-Code

- 1xx: Informational - Request received, continuing process- 2xx: Success - The action was successfully received,        understood, and accepted - 3xx: Redirection - Further action must be taken in order to        complete the request- 4xx: Client Error - The request contains bad syntax or cannot        be fulfilled- 5xx: Server Error - The server failed to fulfill an apparently        valid request

Status-Code    =    Status-text            "100"  : Continue          | "101"  : Switching Protocols          | "200"  : OK          | "201"  : Created          | "202"  : Accepted          | "203"  : Non-Authoritative Information          | "204"  : No Content          | "205"  : Reset Content          | "206"  : Partial Content          | "300"  : Multiple Choices          | "301"  : Moved Permanently          | "302"  : Found          | "303"  : See Other          | "304"  : Not Modified          | "305"  : Use Proxy          | "307"  : Temporary Redirect          | "400"  : Bad Request          | "401"  : Unauthorized          | "402"  : Payment Required          | "403"  : Forbidden          | "404"  : Not Found          | "405"  : Method Not Allowed          | "406"  : Not Acceptable

　　　　　　| "407"  : Proxy Authentication Required          | "408"  : Request Time-out          | "409"  : Conflict          | "410"  : Gone          | "411"  : Length Required          | "412"  : Precondition Failed          | "413"  : Request Entity Too Large          | "414"  : Request-URI Too Large          | "415"  : Unsupported Media Type          | "416"  : Requested range not satisfiable          | "417"  : Expectation Failed          | "500"  : Internal Server Error          | "501"  : Not Implemented          | "502"  : Bad Gateway          | "503"  : Service Unavailable          | "504"  : Gateway Time-out          | "505"  : HTTP Version not supported 详情：https://tools.ietf.org/html/rfc2616#section-10.1.1