PHP-Ajax Cross-Domain Problem Best Solution

Preface

Ajax cross-domain problems are very common in development. For example, the domain of the webpage is client.abc.com, while the domain of the request is server.abc.com. If you access it directly with ajax, you will get the following error:

XMLHttpRequest cannot load http://server.abc.com/server.php. No 'Access-Control-Allow-Origin' header is present on the requested resource.Origin 'http://client.abc.com' is therefore not allowed access.

The Simplest Solution

header('content-type:application/json;charset=utf8');  
// 指定允许其他域名访问  
header('Access-Control-Allow-Origin:*');  
// 响应类型  
header('Access-Control-Allow-Methods:POST');  
// 响应头设置  
header('Access-Control-Allow-Headers:x-requested-with,content-type');

1. Allow Access from a Single Domain

To allow a specific domain client.abc.com to make cross-domain requests, you only need to add the following code at the top of the server.abc.com/a.php file:

header('Access-Control-Allow-Origin:http://client.abc.com');

2. Allow Access from Multiple Domains

To allow multiple domains, add the following code at the top of the server.php file:

$origin = isset($_SERVER['HTTP_ORIGIN'])? $_SERVER['HTTP_ORIGIN'] : '';
//$_SERVER['HTTP_ORIGN']获得请求访问的域名

$allow_origin = array(
  'http://client.abc.com',
  'http://client2.abc.com'
);

if(in_array($origin, $allow_origin)){
header('Access-Control-Allow-Origin:'.$origin);
}

3. Allow Access from All Domains

To allow all domains to access, you only need to add the following code at the top of the php file:

header('Access-Control-Allow-Origin:*');

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