Download File from dynamic url

Hi everyone, hope someone could help me.

Here's the issue:

I have an URL like this "http://site.com/imgsrc/getimage.php?id=JK2Q", and if I open that url in a browser... I get directly the download of an attached image, because the headers are Content-disposition: attachment (maybe default.jpg)

app.js

var url = "http://site.com/imgsrc/getimage.php?id=JK2Q"
var myFile = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory, imageDirName, url);
 
// Create the HTTP client to download the asset.
    var xhr = Ti.Network.createHTTPClient();
 
    xhr.onload = function() {
        Ti.API.info( this.getResponseHeader('Content-Length') ); // 10504
        Ti.API.info( this.getResponseHeader('Content-Type') ); // image/jpg
        if (xhr.status == 200) {
            myFile.write(xhr.responseData);
            Ti.API.log(file.nativePath); // this shows .../iPhone%20Simulator/7.1/Applications/Documents/localimages/http://site.com/imgsrc/getimage.php
        };
    };
 
        // Issuing a request to the remote URL
        xhr.open('HEAD', url);
        // Finally, sending the request out.
        xhr.send();

I'm trying to download that image file from the sample url but I'm getting the getimage.php file instead off default.jpg or whatever the file is.

I don't know what needs to be done. Please help!