Javascript Facebook API POST 多部分/表单数据

Question

最近几天我一直被这个问题难倒了。如果有人能指出我正确的方向，我将不胜感激!我一直在尝试弄清楚如何通过 facebooks graph api 发布图像。

我通过他们的图形 API 从 Facebook 下载了一张图像，该图像正确显示在 Canvas 元素中。我正在通过在其上绘制文本来修改此元素，然后想将其上传回 facebook。我被困在上传中。

以下是我查看过的有用链接，但我仍然卡住了:

Facebook Graph API - upload photo using JavaScript讨论使用 multipart/form-data 通过帖子请求上传到 facebook。

https://gist.github.com/andyburke/1498758用于创建多部分表单数据并向 Facebook 发送请求以发布图像的代码。

这是我用来尝试将图片发布到 facebook 的代码

if ( XMLHttpRequest.prototype.sendAsBinary === undefined ) {
    XMLHttpRequest.prototype.sendAsBinary = function(string) {
        var bytes = Array.prototype.map.call(string, function(c) {
            return c.charCodeAt(0) & 0xff;
        });
        //this.send(new Uint8Array(bytes).buffer); //depreciated warning
        this.send(new Uint8Array(bytes));
    };
}

// This function takes an array of bytes that are the actual contents of the image file.
// In other words, if you were to look at the contents of imageData as characters, they'd
// look like the contents of a PNG or GIF or what have you.  For instance, you might use
// pnglib.js to generate a PNG and then upload it to Facebook, all from the client.
//
// Arguments:
//   authToken - the user's auth token, usually from something like authResponse.accessToken
//   filename - the filename you'd like the uploaded file to have
//   mimeType - the mime type of the file, eg: image/png
//   imageData - an array of bytes containing the image file contents
//   message - an optional message you'd like associated with the image

function PostImageToFacebook( authToken, filename, mimeType, imageData, message )
{
    console.log("filename " +  filename);
    console.log("mimeType " + mimeType);
    console.log("imageData " + imageData);
    console.log("message " + message);

    // this is the multipart/form-data boundary we'll use
    var boundary = '----ThisIsTheBoundary1234567890';

    // let's encode our image file, which is contained in the var
    var formData = '--' + boundary + '\r\n'
    formData += 'Content-Disposition: form-data; name="source"; filename="' + filename + '"\r\n';
    formData += 'Content-Type: ' + mimeType + '\r\n\r\n';
    for ( var i = 0; i < imageData.length; ++i )
    {
        formData += String.fromCharCode( imageData[ i ] & 0xff );
    }
    formData += '\r\n';
    formData += '--' + boundary + '\r\n';
    formData += 'Content-Disposition: form-data; name="message"\r\n\r\n';
    formData += message + '\r\n'
    formData += '--' + boundary + '--\r\n';

    var xhr = new XMLHttpRequest();
    xhr.open( 'POST', 'https://graph.facebook.com/me/photos?access_token=' + authToken, true );
    xhr.onload = xhr.onerror = function() {
        console.log( xhr.responseText );
    };
    xhr.setRequestHeader( "Content-Type", "multipart/form-data; boundary=" + boundary );
    xhr.sendAsBinary( formData );
    console.log(formData);
}

对 PostImageToFacebook 函数的调用导致以下错误:

{
   "error": {
      "type": "Exception",
      "message": "Your photos couldn't be uploaded. Photos should be less than 4 MB and saved as JPG, PNG, GIF or TIFF files.",
      "code": 1366046
}

我记录了我在下面粘贴的 formData 的输出:

------ThisIsTheBoundary1234567890
Content-Disposition: form-data; name="source"; filename="MemeImage.png"
Content-Type: image/png

------ThisIsTheBoundary1234567890
Content-Disposition: form-data; name="message"

Posting a meme image
------ThisIsTheBoundary1234567890--

Answer 1

尝试替换

for ( var i = 0; i < imageData.length; ++i )
{
    formData += String.fromCharCode( imageData[ i ] & 0xff );
}

与

formData += imageData;