Mapview仅在使用intent启动时出现（tabhost）

Question

我在FragmentActivity中使用了mapview，只有在意图调用时才会显示地图。在tabhost选项卡中，它保持空白.GetHttpResponse提供数据。

UPDATE  A
SET     A.Value     =   B.Value
FROM    Table_A         AS A
INNER JOIN 
(
    SELECT  B.ID        ,
            B.Value
    FROM    Table_B     AS B
)                       AS B ON B.ID = A.ID
WHERE   A.ID = 1

布局

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.layout_dua);

    mMapView = (MapView) findViewById(R.id.map);
    mMapView.onCreate(savedInstanceState);

    mMapView.onResume();
    progressBar = (ProgressBar) findViewById(R.id.progressBar);

    new GetHttpResponse(MyMapFragment1.this).execute();

    mMapView.getMapAsync(this);
    }