Android --Fragment中异步HTTP请求

1、自定义异步Task

    /**
     * 异步获取实时数据
     */
    public class TimerDataTask extends AsyncTask<Void, Void, Boolean> {

        @Override
        protected Boolean doInBackground(Void... params) {
            String getUrl = mUrl + "/RealTimeData.ashx?type=data";
            URL loginUrl = null;
            InputStream in = null;
            HttpURLConnection conn = null;

            //初始化列表
            mDataList = new ArrayList<DataListItem>();
            try {
                loginUrl = new URL(getUrl);
                conn = (HttpURLConnection) loginUrl.openConnection();
                conn.setRequestProperty("Charset", "UTF-8");
                if (conn.getResponseCode() == 200) {
                    in = new BufferedInputStream(conn.getInputStream());
                    Scanner scanner = new Scanner(in).useDelimiter("\\A");
                    String result = scanner.hasNext() ? scanner.next() : "";
                    Log.e(mLogTimerData,result);
                }
                conn.disconnect();
            } catch (IOException ex){
                Log.e(getString(R.string.log_e_url_error), ex.toString());
            }catch (JSONException ex){
                Log.e(getString(R.string.log_e_json_error), ex.toString());
            }

            return true;
        }

        @Override
        protected void onPostExecute(final Boolean success) {
//            Message msg = new Message();
//            uiHandler.sendMessage(msg);
            if(getActivity() != null) {
                getActivity().runOnUiThread(uiRefreshThread);
            }
            mTask=null;
        }
        @Override
        protected void onCancelled() {
            mTask=null;
        }
    }

2、在主线程刷新ListView

    Runnable uiRefreshThread =new Runnable() {
        @Override
        public void run() {
            if(getActivity() != null) {
                //初始化Adapter
                mAdapter = new DataListAdapter(getActivity()
                        , R.layout.fragment_data_list_item, mDataList);
                // Set the adapter
                mListView.setAdapter(mAdapter);
                mSwipeLayout.setRefreshing(false);
                mListView.setEnabled(true);
            }
        }
    };

    Runnable uiThread = new Runnable(){
        @Override
        public void run(){
            mListView.setEnabled(false);
        }
    };

3、定时任务

    Timer timer = new Timer();
    TimerTask task = new TimerTask() {
        @Override
        public void run() {
            if(getActivity() !=null) {
                getActivity().runOnUiThread(uiThread);
                mTask = new TimerDataTask();
                mTask.execute((Void) null);
            }
        }
    };

每次刷新都是，重新new一个Adapter对象，使用notifyDataSetChanged()，会出现不定时BUG异常