Android异步请求

class MyTask_SendMessage extends AsyncTask<String, Void, String> {

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            ShowResponseFromTuling(result);
        }

        @Override
        protected String doInBackground(String... arg0) {
            HttpPost request = new HttpPost(arg0[0]);
            // 必须要添加该Http头才能调用WebMethod时返回JSON数据
            request.addHeader("Content-Type", "application/json; charset=utf-8");

            try {
                // 添加参数
                JSONObject param = new JSONObject();
                param.put("key", Constants.API_KEY);
                param.put("info", arg0[1]);
                HttpEntity entity = new StringEntity(param.toString(), "utf-8");
                request.setEntity(entity);

                // 发送请求并获取反馈
                HttpResponse response = new DefaultHttpClient()
                        .execute(request);
                int code = response.getStatusLine().getStatusCode();
                if (code == 200) {
                    String result = EntityUtils.toString(response.getEntity());
                    return result.toString();
                }
                return "";
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return "";
        }

    }