无法抓取http POST文件上传进度(Android)

public class FileUploader {
    private static final int BUFFER_SIZE = 4096;

    public interface ProgressListener {
        void onProgressUpdate(int progress);
    }

    public static void uploadFile(final String url, final String filePath, final ProgressListener listener) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    File file = new File(filePath);
                    long fileSize = file.length();
                    long uploadedSize = 0;

                    URL uploadUrl = new URL(url);
                    HttpURLConnection connection = (HttpURLConnection) uploadUrl.openConnection();
                    connection.setDoOutput(true);
                    connection.setRequestMethod("POST");

                    OutputStream outputStream = connection.getOutputStream();
                    FileInputStream fileInputStream = new FileInputStream(file);
                    byte[] buffer = new byte[BUFFER_SIZE];
                    int bytesRead;
                    while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                        outputStream.write(buffer, 0, bytesRead);
                        uploadedSize += bytesRead;
                        int progress = (int) (uploadedSize * 100 / fileSize);
                        if (listener != null) {
                            listener.onProgressUpdate(progress);
                        }
                    }
                    fileInputStream.close();
                    outputStream.close();

                    // 处理服务器的响应
                    int responseCode = connection.getResponseCode();
                    if (responseCode == HttpURLConnection.HTTP_OK) {
                        // 文件上传成功
                    } else {
                        // 文件上传失败
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}

FileUploader.uploadFile("http://example.com/upload", "/path/to/file", new FileUploader.ProgressListener() {
    @Override
    public void onProgressUpdate(int progress) {
        // 更新UI显示上传进度
    }
});