How do I send a cross-domain POST request via Java

Question

How do I send a cross-domain POST request via JavaScript?

Notes - it shouldn't refresh the page, and I need to grab and parse the response afterwards.

Answer 1

CORS is for you. CORS is "Cross Origin Resource Sharing", is a way to send cross domain request.Now the XMLHttpRequest2 and Fetch API both support CORS, and it can send both POST and GET request

But it has its limits.Server need to specific claim the Access-Control-Allow-Origin, and it can not be set to '*'.

And if you want any origin can send request to you, you need JSONP (also need to set Access-Control-Allow-Origin, but can be '*')

For lots of request way if you don't know how to choice, I think you need a full functional component to do that.Let me introduce a simple component https://github.com/Joker-Jelly/catta

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If you are using modern browser (> IE9, Chrome, FF, Edge, etc.), Very Recommend you to use a simple but beauty component https://github.com/Joker-Jelly/catta.It have no dependence, Less than 3KB, and it support Fetch, AJAX and JSONP with same deadly sample syntax and options.

catta('./data/simple.json').then(function (res) {
  console.log(res);
});

It also it support all the way to import to your project, like ES6 module, CommonJS and even <script> in HTML.

Answer 2

1. Create an iFrame,
2. put a form in it with Hidden inputs,
3. set the form's action to the URL,
4. Add iframe to document
5. submit the form

Pseudocode

 var ifr = document.createElement('iframe');
 var frm = document.createElement('form');
 frm.setAttribute("action", "yoururl");
 frm.setAttribute("method", "post");

 // create hidden inputs, add them
 // not shown, but similar (create, setAttribute, appendChild)

 ifr.appendChild(frm);
 document.body.appendChild(ifr);
 frm.submit();

You probably want to style the iframe, to be hidden and absolutely positioned. Not sure cross site posting will be allowed by the browser, but if so, this is how to do it.

Answer 3

If you have access to all servers involved, put the following in the header of the reply for the page being requested in the other domain:

PHP:

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

For example, in Drupal's xmlrpc.php code you would do this:

function xmlrpc_server_output($xml) {
    $xml = '<?xml version="1.0"?>'."\n". $xml;
    header('Connection: close');
    header('Content-Length: '. strlen($xml));
    header('Access-Control-Allow-Origin: *');
    header('Content-Type: application/x-www-form-urlencoded');
    header('Date: '. date('r'));
    // $xml = str_replace("\n", " ", $xml); 

    echo $xml;
    exit;
}

This probably creates a security problem, and you should make sure that you take the appropriate measures to verify the request.

Answer 4

1. Create two hidden iframes (add "display: none;" to the css style). Make your second iframe point to something on your own domain.

2. Create a hidden form, set its method to "post" with target = your first iframe, and optionally set enctype to "multipart/form-data" (I'm thinking you want to do POST because you want to send multipart data like pictures?)

3. When ready, make the form submit() the POST.

4. If you can get the other domain to return javascript that will do Cross-Domain Communication With Iframes (http://softwareas.com/cross-domain-communication-with-iframes) then you are in luck, and you can capture the response as well.

Of course, if you want to use your server as a proxy, you can avoid all this. Simply submit the form to your own server, which will proxy the request to the other server (assuming the other server isn't set up to notice IP discrepancies), get the response, and return whatever you like.

Answer 5

This is an old question, but some new technology might help someone out.

If you have administrative access to the other server then you can use the opensource Forge project to accomplish your cross-domain POST. Forge provides a cross-domain JavaScript XmlHttpRequest wrapper that takes advantage of Flash's raw socket API. The POST can even be done over TLS.

The reason you need administrative access to the server you are POSTing to is because you must provide a cross-domain policy that permits access from your domain.

http://github.com/digitalbazaar/forge