Android Multipart upload - getPart() on server side returns null

Question

I'm trying to upload images from android app to my server. While sending 'httpPost' seems to work fine, on the server side code, I'm getting null while executing the HTTPServletRequest.getPart("filepart").

Android Activity code

    public class ImageUpload extends Activity {

private static int RESULT_LOAD_IMAGE = 1;
Bitmap bm;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.image_upload);

    Button buttonLoadImage = (Button) findViewById(R.id.buttonLoadPicture);
    buttonLoadImage.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            Intent i = new Intent(
                    Intent.ACTION_PICK,
                    android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

            startActivityForResult(i, RESULT_LOAD_IMAGE);
        }
    });
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK
            && null != data) {
        Uri selectedImage = data.getData();
        String[] filePathColumn = { MediaStore.Images.Media.DATA };

        Cursor cursor = getContentResolver().query(selectedImage,
                filePathColumn, null, null, null);
        cursor.moveToFirst();

        int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
        String picturePath = cursor.getString(columnIndex);
        cursor.close();

        ImageView imageView = (ImageView) findViewById(R.id.imgView);
        bm = BitmapFactory.decodeFile(picturePath);
        imageView.setImageBitmap(bm);

        SendHttpRequestTask t = new SendHttpRequestTask();
        t.execute();
    }
}

public void executeMultipartPost() {

}

private class SendHttpRequestTask extends AsyncTask<String, Void, String> {

    @Override
    protected String doInBackground(String... params) {
        try {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            bm.compress(CompressFormat.JPEG, 75, bos);
            byte[] data = bos.toByteArray();
            HttpClient httpClient = new DefaultHttpClient();
            HttpPost postRequest = new HttpPost(
                "http://192.168.43.85:8080/Albums/ImageUpload");
            ByteArrayBody bab = new ByteArrayBody(data, "forest.jpg");
            MultipartEntity reqEntity = new MultipartEntity();
            reqEntity.addPart("userfile", bab);
            postRequest.setEntity(reqEntity);
            httpClient.execute(postRequest);

        } catch (Exception e) {
            // handle exception here
            Log.e(e.getClass().getName(), e.getMessage());
        }
        return null;
    }

}

}

My Server Side Code

@WebServlet("/ImageUpload")
@MultipartConfig
public class ImageUpload extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
 * @see HttpServlet#HttpServlet()
 */
public ImageUpload() {
    super();
    // TODO Auto-generated constructor stub
}

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
     try {
            List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
            for (FileItem item : items) {
                if (item.isFormField()) {
                    // Process regular form field (input type="text|radio|checkbox|etc", select, etc).
                    String fieldname = item.getFieldName();
                    String fieldvalue = item.getString();
                    // ... (do your job here)
                } else {
                    // Process form file field (input type="file").
                    String fieldname = item.getFieldName();
                    InputStream filecontent =  request.getPart("userfile").getInputStream();
                    OutputStream out = new FileOutputStream("C:\\test.jpg" );
                    IOUtils.copy(filecontent, out); // The function is below
                    out.flush();
                    out.close();
                    request.getRequestDispatcher("index.jsp").forward(request, response);
                }
            }
        } catch (FileUploadException e) {
            throw new ServletException("Cannot parse multipart request.", e);
        }
}

}

While executing this, I'm getting NullPointerException on getPart() method on server side. Appreciate any help/suggestions on this.