跨域请求POST的解决方法介绍

 // 请求代码示例
 $.ajax({
 url: url,
 type: "POST",
 data: metadata,
 dataType: 'json',
 xhrFields: { 
 withCredentials: true 
 }, 
 crossDomain: true,
 success: function(){},
 error: function(){}
 });

 ## 服务端设置允许跨域代码，eg:
 header("Access-Control-Allow-Credentials: true")；

 header("Access-Control-Allow-Origin: http://www.xxx.com");

 ## 设置成功后，在接口请求的Response Headers会看到一下以下允许跨越信息
 {
 Access-Control-Allow-Credentials:true
 Access-Control-Allow-Headers:x-requested-with,content-type
 Access-Control-Allow-Methods:POST
 Access-Control-Allow-Origin:http://www.aipai.com
 }

 // 代码
 $.ajax({
 ...
 xhrFields: { 
 withCredentials: true 
 },
 ...
 });