@Override
 public void handleMessage(Message msg) {
   hideLoadingDialog(pDialog);
   switch (msg.what) {
     case Constants.MSG_CONNECTION_UNAVAILABLE: // 客户端与服务器没有连接
       new AlertDialog.Builder(mContext)
           .setTitle(R.string.prompt)
           .setMessage(R.string.connection_unavailable)
           .setNegativeButton(android.R.string.cancel, null)
           .setCancelable(false)
           .setPositiveButton(android.R.string.ok, null)
           .show();
       break;
     case Constants.MSG_SEND_ADD_FRIEND_REQUEST: // 发送添加好友的请求
       SystemUtil.makeShortToast(R.string.contact_send_add_friend_request_success);
       break;
     case Constants.MSG_ALREAD_ADDED: // 提示已添加过了
       SystemUtil.makeShortToast(R.string.contact_send_add_friend_request_repeat);
       break;
     default:
       break;
   }
 }
 @Override
 protected void onPostExecute(List<User> result) {
   users.clear();
   if (SystemUtil.isNotEmpty(result)) {
     users.addAll(result);
   }
   if (adapter == null) {
     adapter = new FriendResultAdapter(users, mContext);
     lvResult.setAdapter(adapter);
     lvResult.setEmptyView(emptyView);
   } else {
     if (lvResult.getEmptyView() == null) {
       lvResult.setEmptyView(emptyView);
     }
     adapter.notifyDataSetChanged();
   }
   hideLoadingDialog(pDialog);
 }