Question

我让我的用户将文件下载到云后，我希望我的应用程序重新启动其加载程序。

以前，当我以下列方式编写代码时，onLoadFinished并不总是被调用（随机）

public void reloadAfterOpenFromCloud() {
    LoaderManager loaderManager = this.getLoaderManager();
    loaderManager.restartLoader(0, bundle, this);
}

在参考Android - onLoadFinished not called中的讨论后，我将代码修改为

public void reloadAfterOpenFromCloud() {
    // https://stackoverflow.com/questions/16014992/android-onloadfinished-not-called
    // This seems to be a realiable way, to make sure onCreateLoader and onLoadFinished will
    // be called.
    LoaderManager loaderManager = this.getLoaderManager();
    Loader loader = loaderManager.getLoader(0);
    if (loader != null) {
        loaderManager.destroyLoader(0);
    }
    loaderManager.restartLoader(0, bundle, this);
}

这减少了不调用onLoadFinished的机会。但是，如果我

，它会随机发生

在我的应用上执行清除缓存，清除卸载。
安装应用。
运行reloadAfterOpenFromCloud。同样，随机，onLoadFinished将不会被调用。

如果未调用onLoadFinished，如果我再次运行reloadAfterOpenFromCloud，则会调用onLoadFinished。

我正在使用最新的com.android.support:support-v4:25.0.0和targetSdkVersion 25。

我想知道，是否有任何可行的解决方法，以确保在重新启动加载程序时始终调用onLoadFinished？

以下是我的代码段的一部分。

public void reloadAfterOpenFromCloud() {
    // https://stackoverflow.com/questions/16014992/android-onloadfinished-not-called
    // This seems to be a realiable way, to make sure onCreateLoader and onLoadFinished will
    // be called.
    LoaderManager loaderManager = this.getLoaderManager();
    Loader loader = loaderManager.getLoader(0);
    if (loader != null) {
        loaderManager.destroyLoader(0);
    }
    loaderManager.restartLoader(0, bundle, this);
}

static class HomeMenuRowInfosLoader extends AsyncTaskLoader<List<HomeMenuRowInfo>> {

    private List<HomeMenuRowInfo> homeMenuRowInfos = null;

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

    @Override
    public List<HomeMenuRowInfo> loadInBackground() {
        ...
        return homeMenuRowInfos;
    }

    /**
     * Handles a request to cancel a load.
     */
    @Override 
    public void onCanceled(List<HomeMenuRowInfo> homeMenuRowInfos) {
        super.onCanceled(homeMenuRowInfos);
    }

    /**
     * Handles a request to stop the Loader.
     * Automatically called by LoaderManager via stopLoading.
     */
    @Override 
    protected void onStopLoading() {
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

    /**
     * Handles a request to start the Loader.
     * Automatically called by LoaderManager via startLoading.
     */
    @Override        
    protected void onStartLoading() {
        if (this.homeMenuRowInfos != null) {
            deliverResult(this.homeMenuRowInfos);
        }

        if (takeContentChanged() || this.homeMenuRowInfos == null) {
            forceLoad();
        }
    }

    /**
     * Handles a request to completely reset the Loader.
     * Automatically called by LoaderManager via reset.
     */
    @Override 
    protected void onReset() {
        super.onReset();

        // Ensure the loader is stopped
        onStopLoading();

        // At this point we can release the resources associated with 'apps'
        // if needed.
        this.homeMenuRowInfos = null;
    }        
}

@Override
public Loader<List<HomeMenuRowInfo>> onCreateLoader(int arg0, Bundle bundle) {
    return new HomeMenuRowInfosLoader(this.getActivity());
}

// Not being called always when restart loader
@Override
public void onLoadFinished(Loader<List<HomeMenuRowInfo>> arg0, List<HomeMenuRowInfo> homeMenuRowInfos) {
    ...

Answer 1

您需要在HomeMenuRowInfosLoader中实现某种观察者，当用户完成云文件传输时，该观察者将调用onContentChanged()。

如果永远不会调用onContentChanged()，则takeContentChanged()将始终返回false，forceLoad()将在第一次加载后onStartLoading()内调用homeMenuRowInfos { {1}}不等于null。

加载器重新启动时，并不总是调用onLoadFinished

1 个答案: