如何将跨域请求从客户端发送到服务器？

Question

I am using Google Drive API but while retrieving data from client side I get this error:

XMLHttpRequest cannot load url.  No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost' is therefore not allowed access. 

Note that I am not allowed to change headers.

Is there a way to request cross domain?

var req = {
    action: 'getFiles',
};  

this.getJSON('drive.php', req, function(serverData)
{
    console_log(serverData);

});

Above code gives this error. How can I solve this problem?

One option:

var url = 'drive.php';


$.ajax({
   type: 'GET',
    url: url,
    async: false,
    jsonpCallback: 'jsonCallback',
    data: {action: 'getFiles'},
    contentType: "application/json",
    dataType: 'jsonp',
    success: function(json) {
       console.dir(json.sites);
    },
    error: function(e) {
       console.log(e.message);
    }
});

Still it gives GET error

Answer 1

You can make a request using JSONP; see the following for examples. http://www.sitepoint.com/jsonp-examples/

An example from that site:

(function($) {
var url = 'http://www.jquery4u.com/scripts/jquery4u-sites.json?callback=?';


    $.ajax({
       type: 'GET',
        url: url,
        async: false,
        jsonpCallback: 'jsonCallback',
        contentType: "application/json",
        dataType: 'jsonp',
        success: function(json) {
           console.dir(json.sites);
        },
        error: function(e) {
           console.log(e.message);
        }
    });

    })(jQuery)

;

Answer 2

Not really. The cross domain request is not allowed for security reasons. What you can do is the following:

Write a PHP script which just forwards your request and place this PHP script in the same server as your JavaScript. Your JS will thereby perform the request on the domain and will not end up with an error.

Answer 3

In php you need

header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST/GET');

insert into header file .php, it's allow client POST data with method POST/GET to server and get receiver from it ...