Android Loader不会在屏幕旋转时触发回调

Question

我正在使用AsyncTaskLoader.我有一个已经实现的活动LoaderCallbacks(支持库).

我有断点调试并放入日志,加载器传递结果,但是第二次onLoadFinished没有触发回调.奇怪的是 - 当我再次向后旋转时它起作用,当我回到它时,我开始的方向会得到回调.

在我的活动中onResume:

LoaderManager lm = getSupportLoaderManager();
Loader loader = lm.initLoader(0, null, new LoaderManager.LoaderCallbacks<String>() {

        @Override
        public Loader<String> onCreateLoader(int i, Bundle bundle) {
            Loader<String> loader = new TestLoader(MainActivity.this);
            return loader;
        }

        @Override
        public void onLoadFinished(Loader<String> stringLoader, String s) {
            Log.d(Application.TAG, "OnLoadFinished " + s);
            doStuff(s);
        }

        @Override
        public void onLoaderReset(Loader<String> stringLoader) {
            // NOP
        }
    });

在我的装载机:

public class TestLoader extends AsyncTaskLoader<String> {
    private String mData;

    public TestLoader(Context context) {
        super(context);
    }

    // This get's called after a loader is initialized or a loader 
    // that is alive still is reset
    @Override
    public void onStartLoading() {
        if (mData != null) { // Have our data loaded, just deliver it!
            deliverResult(mData);
        }
        if (takeContentChanged() || mData == null) {
            forceLoad();
        }
    }

    // This is called when an Activity or Fragment requests a loader 
    // to be reset because they want new data
    @Override
    public void onReset() {
        mData = null;
        // Ensure that the old task is cancelled if it was running
        // We do NOT have to call forceLoad here because onStartLoading 
        // will get called after this
        cancelLoad();
    }

    // Here we just want to store our own data we got and reset our boolean
    @Override
    public void deliverResult(String data) {
        Log.d(Application.TAG, "deliverResult " + data);
        mData = data;
        super.deliverResult(mData);
    }

    @Override
    public String loadInBackground() {
       // returns content from a content provider ... 
    }
}

真的很困惑这个,我是Android的新手,所以也许这对其他人来说很明显:)

Answer 1

如果是a 或者是a,你必须至少简单地调用getSupportLoaderManager()/ getLoaderManager()in .实际可以在其他地方.否则,加载程序将处于停止状态,即使完成加载也不会传递结果.我怀疑这是因为加载器管理器不会将旧的加载器重新连接到新的加载器,除非上述调用是在新的中进行的.onCreate()ActivityonActivityCreated()FragmentinitLoader()ActivityActivityonCreate()