@Override
 protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   mDownloadMan = AcApp.getDownloadManager();
   mBar = getSupportActionBar();
   mBar.setTitle("下载管理");
   if (!AcApp.isExternalStorageAvailable()) {
     setContentView(R.layout.no_sd_layout);
     return;
   }
   setContentView(R.layout.list_layout);
   Intent service = new Intent(this, DownloadService.class);
   bindService(service, conn, BIND_AUTO_CREATE);
   mStateArray = getResources().getStringArray(R.array.download_state);
   // TODO 换成popupwindow或者其他的显示方式
   ArrayAdapter<CharSequence> adapter =
       ArrayAdapter.createFromResource(
           mBar.getThemedContext(), R.array.download_state, android.R.layout.simple_spinner_item);
   adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
   mBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
   mBar.setListNavigationCallbacks(adapter, this);
   initView();
 }