HTTP 204 与 205 应用

HTTP 204(no content)表示响应执行成功，但没有数据返回，浏览器不用刷新，不用导向新页面。
HTTP 205(reset content) 表示响应执行成功，重置页面（Form表单），方便用户下次输入。

使用ajax时，当只需要知道响应成功或失败的情况，则可以使用状态码HTTP 204来代替HTTP 200，减少多余的数据传输。

例子：ajax提交用户名、文章id，记录用户访问过该文章

  $(document).ready(function(){
    $.get("api.php", {name:'fdipzone',article_id:'100'});
  })

<?php

$name = $_GET['name'];
$article_id = $_GET['article_id'];

// do sth

header('HTTP/1.1 204 No Content');

?>

HTTP 状态码header输出：

/**
 * HTTP Protocol defined status codes
 * @param int $num
 */
function HTTPStatus($num) {
   
   static $http = array (
       100 => "HTTP/1.1 100 Continue",
       101 => "HTTP/1.1 101 Switching Protocols",
       200 => "HTTP/1.1 200 OK",
       201 => "HTTP/1.1 201 Created",
       202 => "HTTP/1.1 202 Accepted",
       203 => "HTTP/1.1 203 Non-Authoritative Information",
       204 => "HTTP/1.1 204 No Content",
       205 => "HTTP/1.1 205 Reset Content",
       206 => "HTTP/1.1 206 Partial Content",
       300 => "HTTP/1.1 300 Multiple Choices",
       301 => "HTTP/1.1 301 Moved Permanently",
       302 => "HTTP/1.1 302 Found",
       303 => "HTTP/1.1 303 See Other",
       304 => "HTTP/1.1 304 Not Modified",
       305 => "HTTP/1.1 305 Use Proxy",
       307 => "HTTP/1.1 307 Temporary Redirect",
       400 => "HTTP/1.1 400 Bad Request",
       401 => "HTTP/1.1 401 Unauthorized",
       402 => "HTTP/1.1 402 Payment Required",
       403 => "HTTP/1.1 403 Forbidden",
       404 => "HTTP/1.1 404 Not Found",
       405 => "HTTP/1.1 405 Method Not Allowed",
       406 => "HTTP/1.1 406 Not Acceptable",
       407 => "HTTP/1.1 407 Proxy Authentication Required",
       408 => "HTTP/1.1 408 Request Time-out",
       409 => "HTTP/1.1 409 Conflict",
       410 => "HTTP/1.1 410 Gone",
       411 => "HTTP/1.1 411 Length Required",
       412 => "HTTP/1.1 412 Precondition Failed",
       413 => "HTTP/1.1 413 Request Entity Too Large",
       414 => "HTTP/1.1 414 Request-URI Too Large",
       415 => "HTTP/1.1 415 Unsupported Media Type",
       416 => "HTTP/1.1 416 Requested range not satisfiable",
       417 => "HTTP/1.1 417 Expectation Failed",
       500 => "HTTP/1.1 500 Internal Server Error",
       501 => "HTTP/1.1 501 Not Implemented",
       502 => "HTTP/1.1 502 Bad Gateway",
       503 => "HTTP/1.1 503 Service Unavailable",
       504 => "HTTP/1.1 504 Gateway Time-out"        
   );
   
   header($http[$num]);
}