装载机重新启动的方向变化 [英] Loader restarts on orientation change

问题描述

在Android的文档在<一个发现装载机href="http://developer.android.com/guide/components/loaders.html">http://developer.android.com/guide/components/loaders.html它说装载机的特性之一是：

In the Android documentation for Loaders found at http://developer.android.com/guide/components/loaders.html it says one of the properties of loaders is that:

他们自动重新连接到最后装载器的游标时配置更改后正在重建。因此，它们并不需要重新查询他们的数据。

They automatically reconnect to the last loader's cursor when being recreated after a configuration change. Thus, they don't need to re-query their data.

下面code似乎并没有反映这种行为，一个新的Loader在创建完成查询ContentResolver的，那么我旋转屏幕，并重新创建的装载机！

The following code does not seem to mirror that behaviour, a new Loader is created an finishes querying the ContentResolver, then I rotate the screen and the Loader is re-created!

public class ReportFragment extends Fragment implements LoaderCallbacks<Cursor> {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getLoaderManager().initLoader(1, null, this);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_report, container, false);
        return v;
    }

    public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) {
        Log.d("TEST", "Creating loader");
        return new CursorLoader(getActivity(), ResourcesContract.Reports.CONTENT_URI, null, null, null, null);
    }

    public void onLoadFinished(Loader<Cursor> arg0, Cursor arg1) {
        Log.d("TEST", "Load finished");
    }

    public void onLoaderReset(Loader<Cursor> arg0) {

    }

}

下面是从我的logcat的输出：

Here is the output from my logcat:

08-17 16:49:54.474: D/TEST(1833): Creating loader
08-17 16:49:55.074: D/TEST(1833): Load finished
*Here I rotate the screen*
08-17 16:50:38.115: D/TEST(1833): Creating loader
08-17 16:50:38.353: D/TEST(1833): Load finished

任何想法，我在做什么错在这里？

Any idea what I'm doing wrong here?

编辑：

我要指出，我要建到Android谷歌API的版本8，并使用V4支持库。

I should note that I'm building to Android Google API's version 8, and using the v4 support library.

2日编辑：

这是最有可能是由于在支持库中的错误，看看这个bug提交，如果您想进一步的信息：

This is most likely due to a bug in the support library, take a look at this bug submission if you want further information:

<一个href="http://$c$c.google.com/p/android/issues/detail?id=20791&can=5&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars">http://$c$c.google.com/p/android/issues/detail?id=20791&can=5&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars

推荐答案

的onCreate（）在屏幕方向的变化被称为活动以来被破坏并重新创建。

onCreate() gets called during screen orientation change since the activity gets destroyed and recreated.

除非你装载大量的数据，那么它不伤害做的，但你可以试试下面的，如果你想（我没有测试过，但在理论上，我认为这是可行的）。

Unless you're loading a lot of data then it doesn't hurt to do, but you can try the following if you want (I haven't tested it, but in theory I think it would work).

声明静态布尔在全球顶级的类。我的认为的，你还需要一个静态游标引用

Declare a static boolean at the top global of the class. I think you'll also need a static cursor to reference

private static boolean dataDownloaded = false;
private static Cursor oldCursor;

然后在onLoadFinished集dataDownloaded =真

Then on onLoadFinished set dataDownloaded = true

覆盖的onSaveInstanceState保存布尔值

Override onSaveInstanceState to save the boolean value

@Override
protected void onSaveInstanceState(Bundle outSave) {
    outSave.putBoolen("datadownloaded", dataDownloaded);
    oldCursor = adapter.swapCursor(null);
}

和的onCreate添加以下

and onCreate add the following

if (savedInstanceState != null) {
    this.dataDownloaded = savedInstanceState.getBoolean("datadownloaded", false);
}

调整onCreateLoader

adjust your onCreateLoader

public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    CursorLoader cursorLoader;
    if (dataDownloaded) {
        cursorLoader = new CursorLoader(getActivity(),
            null, projection, null, null, null);
        cursorLoader.deliverResult(oldCursor);
    } else {
        CursorLoader cursorLoader = new CursorLoader(getActivity(),
            URI_PATH, projection, null, null, null);
    }

    return cursorLoader;
}

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