Android 使用带有 HttpURLConnection 的 POST 发送文件

我不知道为什么HttpURLConnection类不提供任何方法来发送文件，而不必手动编写文件包装器.以下是我最后做的事情，但如果有人知道更好的解决方案，请告诉我.

输入数据:

Bitmap bitmap = myView.getBitmap();

静态素材:

String attachmentName = "bitmap";
String attachmentFileName = "bitmap.bmp";
String crlf = "\r\n";
String twoHyphens = "--";
String boundary =  "*****";

设置请求:

HttpURLConnection httpUrlConnection = null;
URL url = new URL("http://example.com/server.cgi");
httpUrlConnection = (HttpURLConnection) url.openConnection();
httpUrlConnection.setUseCaches(false);
httpUrlConnection.setDoOutput(true);

httpUrlConnection.setRequestMethod("POST");
httpUrlConnection.setRequestProperty("Connection", "Keep-Alive");
httpUrlConnection.setRequestProperty("Cache-Control", "no-cache");
httpUrlConnection.setRequestProperty(
    "Content-Type", "multipart/form-data;boundary=" + this.boundary);

启动内容包装器:

DataOutputStream request = new DataOutputStream(
    httpUrlConnection.getOutputStream());

request.writeBytes(this.twoHyphens + this.boundary + this.crlf);
request.writeBytes("Content-Disposition: form-data; name=\"" +
    this.attachmentName + "\";filename=\"" + 
    this.attachmentFileName + "\"" + this.crlf);
request.writeBytes(this.crlf);

将Bitmap转换为ByteBuffer:

//I want to send only 8 bit black & white bitmaps
byte[] pixels = new byte[bitmap.getWidth() * bitmap.getHeight()];
for (int i = 0; i < bitmap.getWidth(); ++i) {
    for (int j = 0; j < bitmap.getHeight(); ++j) {
        //we're interested only in the MSB of the first byte, 
        //since the other 3 bytes are identical for B&W images
        pixels[i + j] = (byte) ((bitmap.getPixel(i, j) & 0x80) >> 7);
    }
}

request.write(pixels);

结束内容包装器:

request.writeBytes(this.crlf);
request.writeBytes(this.twoHyphens + this.boundary + 
    this.twoHyphens + this.crlf);

刷新输出缓冲区:

request.flush();
request.close();

获得回复:

InputStream responseStream = new 
    BufferedInputStream(httpUrlConnection.getInputStream());

BufferedReader responseStreamReader = 
    new BufferedReader(new InputStreamReader(responseStream));

String line = "";
StringBuilder stringBuilder = new StringBuilder();

while ((line = responseStreamReader.readLine()) != null) {
    stringBuilder.append(line).append("\n");
}
responseStreamReader.close();

String response = stringBuilder.toString();

关闭响应流:

responseStream.close();

关闭连接:

httpUrlConnection.disconnect();

PS:当然，为了让Android平台满意，我必须将请求包装成private class AsyncUploadBitmaps extends AsyncTask<Bitmap, Void, String>，因为它不喜欢在主线程上有网络请求.