GAE / J：如何从appengine到Facebook发布多部分MIME消息

问题描述

我想将照片（存储在appengine数据库中）发布到Facebook。

I want to post a photo (stored in appengine db) to facebook.

要测试我已经掌握了本地的基本了解： strong>成功：

To test I've got the basic understanding down locally: I've been successful with this form:

<form action="https://graph.facebook.com/7378294228/photos?access_token=AAAAAJPBSAzcBALmz7GOLZCER7Pc2347WQIDIlIFR8e2imWUzeuCKRLrXjAqR6zjaUb4laqkLtJlQlYa7X5ZBd2aNJoLom8M7IlvHfw39QZDZD" method="POST" enctype="multipart/form-data">
<input type="file" name="source" id="source"/>
<input type="text" name="message" value="mymess"/>
<input type="Submit"/>
</form>

（我从最近的一个会话中抓住了access_token，使其工作。）

(I grabbed the access_token from a recent session to make this work.)

以下是我迄今为止在appengine 失败上尝试过的

Here's what I've tried on appengine unsuccessfully so far:

MultipartEntity mpEntity  = new MultipartEntity();
ContentBody cbFile = new ByteArrayBody(imageBytes, "image/jpeg", "w.jpg");
mpEntity.addPart("source", cbFile);

URL url = new URL("https://graph.facebook.com/"+albumUpload.getAlbumID()+"/photos?access_token="+albumUpload.getAuthToken());                   
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");

mpEntity.writeTo(connection.getOutputStream());

if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
   System.err.println("http success!");
}else{
   System.err.println("http failed:"+connection.getResponseCode());
}

我收到一个HTTP 400 - 错误请求。

I get a HTTP 400 - Bad Request.

我添加了这些，以确保它在做某事：

I added these to make sure it was doing something:

System.out.println("mpEntity image content length: "+cbFile.getContentLength());
System.out.println("mpEntity content type:"+mpEntity.getContentType());

导致：

mpEntity image content length: 786145 
mpEntity content type:Content-Type: multipart/form-data; boundary=oMiJCBHGVvZmU7s3FcUGXMbyU23aX_Ow 

我可以在线查看MultipartEntity使用的唯一示例是使用HttpClient的setEntity（）作为因此不适用，因为这是appengine下的URLFetch。

The only examples I can find of MultipartEntity usage online are using HttpClient's setEntity(), as as such don't apply as this is a URLFetch under appengine.

感谢任何帮助/代码。

推荐答案

解决！

我需要添加：

connection.addRequestProperty("Content-length", mpEntity.getContentLength()+"");
connection.addRequestProperty(mpEntity.getContentType().getName(), mpEntity.getContentType().getValue());

另外更改：

MultipartEntity mpEntity  = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);

希望这有助于某人

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