前言：摘抄自Laravel框架的resopn类中。
100 => 'Continue', 101 => 'Switching Protocols', 102 => 'Processing', // RFC2518 103 => 'Early Hints', 200 => 'OK', 201 => 'Created', 202 => 'Accepted', 203 => 'Non-Authoritative Information', 204 => 'No Content', 205 => 'Reset Content', 206 => 'Partial Content', 207 => 'Multi-Status', // RFC4918 208 => 'Already Reported', // RFC5842 226 => 'IM Used', // RFC3229 300 => 'Multiple Choices', 301 => 'Moved Permanently', 302 => 'Found', 303 => 'See Other', 304 => 'Not Modified', 305 => 'Use Proxy', 307 => 'Temporary Redirect', 308 => 'Permanent Redirect', // RFC7238 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 Timeout', 409 => 'Conflict', 410 => 'Gone', 411 => 'Length Required', 412 => 'Precondition Failed', 413 => 'Payload Too Large', 414 => 'URI Too Long', 415 => 'Unsupported Media Type', 416 => 'Range Not Satisfiable', 417 => 'Expectation Failed', 418 => 'I\'m a teapot', // RFC2324 421 => 'Misdirected Request', // RFC7540 422 => 'Unprocessable Entity', // RFC4918 423 => 'Locked', // RFC4918 424 => 'Failed Dependency', // RFC4918 425 => 'Reserved for WebDAV advanced collections expired proposal', // RFC2817 426 => 'Upgrade Required', // RFC2817 428 => 'Precondition Required', // RFC6585 429 => 'Too Many Requests', // RFC6585 431 => 'Request Header Fields Too Large', // RFC6585 451 => 'Unavailable For Legal Reasons', // RFC7725 500 => 'Internal Server Error', 501 => 'Not Implemented', 502 => 'Bad Gateway', 503 => 'Service Unavailable', 504 => 'Gateway Timeout', 505 => 'HTTP Version Not Supported', 506 => 'Variant Also Negotiates', // RFC2295 507 => 'Insufficient Storage', // RFC4918 508 => 'Loop Detected', // RFC5842 510 => 'Not Extended', // RFC2774 511 => 'Network Authentication Required',