我在这个函数中有一个问题，这个代码是在后台运行的，上传摄像头拍摄的图像并转换成base 46，我有一些错误。请参见此图像：

protected String doInBackground(Void... params) {

        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        nameValuePairs.add(new BasicNameValuePair("base64", ba1));
        nameValuePairs.add(new BasicNameValuePair("ImageName", System.currentTimeMillis() + ".jpg"));
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(URL);
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);
            String st = EntityUtils.toString(response.getEntity());
            Log.v("log_tag", "In the try Loop" + st);

        } catch (Exception e) {
            Log.v("log_tag", "Error in http connection " + e.toString());
        }
        return "Success";

    }

请帮我解释一下语法