@Override
 protected void onPullDownListViewRefresh(PullToRefreshListView refreshListView) {
   super.onPullDownListViewRefresh(refreshListView);
   if (mNewsTask != null) {
     return;
   }
   mNewsTask = new NewsTask(NewsTask.TYPE_REFRESH);
   mNewsTask.execute(mNewsURL);
 }
 @Override
 public void onActivityCreated(Bundle savedInstanceState) {
   super.onActivityCreated(savedInstanceState);
   setListAdapter(mAdapter);
   if (mNewsTask == null && mAdapter.isEmpty()) {
     mNewsTask = new NewsTask(NewsTask.TYPE_REFRESH);
     mNewsTask.execute(mNewsURL);
   }
 }
 @Override
 public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   mAdapter = new NewsAdapter();
   Bundle args = getArguments();
   if (args != null) {
     mNewsURL = args.getString(ARG_URL);
   } else {
     mNewsURL = getString(R.string.host, "/news");
   }
 }
 @Override
 protected void onPullUpListViewRefresh(PullToRefreshListView refreshListView) {
   super.onPullDownListViewRefresh(refreshListView);
   if (mNewsTask != null) {
     return;
   }
   if (!TextUtils.isEmpty(mMoreURLPath)) {
     mNewsTask = new NewsTask(NewsTask.TYPE_LOADMORE);
     mNewsTask.execute(getString(R.string.host, mMoreURLPath));
     mMoreURLPath = null;
   } else {
     // 防止moreurl解析错误
     mNewsTask = new NewsTask(NewsTask.TYPE_REFRESH);
     mNewsTask.execute(mNewsURL);
   }
 }
 @Override
 public void onDestroy() {
   super.onDestroy();
 }