java - 应用程序在执行 AsyncTask 后不显示任何内容

Question

这是一个简单的小部件，显示从外部存储中获取的一组位图。它基本上可以工作，但会监视 App 在其主线程上做太多工作，所以我把东西放在 AsyncTask 中，但是小部件仍然是空的，没有加载位图。这是有效的代码:

public class PhotosLoader /*extends AsyncTask<Void, Void ,ArrayList<Bitmap>> */ {
    private Context mContext;
    private RemoteViews views;
    private ArrayList<Bitmap> images;

    public PhotosLoader (Context context, RemoteViews views){
        mContext = context;
        this.views = views;
    }

    public ArrayList<Bitmap> LoadPhotos() {
        PhotosReader PR = new PhotosReader();
        images = PR.getPhotosArray(mContext);
        PhotosModifier PM = new PhotosModifier();
        ArrayList<Bitmap> bitmaps = PM.getResizedPhotosBitmap(images);
        return bitmaps;
    }

    public void inflatePhotos(ArrayList<Bitmap> bitmaps){
        views.setImageViewBitmap(R.id.imageView, bitmaps.get(0));
        views.setImageViewBitmap(R.id.imageView2, bitmaps.get(1));
        views.setImageViewBitmap(R.id.imageView3, bitmaps.get(2));
        views.setImageViewBitmap(R.id.imageView4, bitmaps.get(3));
        views.setImageViewBitmap(R.id.imageView5, bitmaps.get(4));
    }
}

onUpdate 方法:

 public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // There may be multiple widgets active, so update all of them
        for (int appWidgetId : appWidgetIds) {
            updateAppWidget(context, appWidgetManager, appWidgetId);

            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.new_app_widget);
            PhotosLoader PL = new PhotosLoader(context, views);
            ArrayList<Bitmap> bitmaps = PL.LoadPhotos();
            PL.inflatePhotos(bitmaps);
        }
    }

还有一些代码没有:

public class PhotosLoader extends AsyncTask<Void, Void ,ArrayList<Bitmap>> {
    private Context mContext;
    private RemoteViews views;
    private ArrayList<Bitmap> images;

    public PhotosLoader (Context context, RemoteViews views){
        mContext = context;
        this.views = views;
    }

    @Override
    protected ArrayList<Bitmap> doInBackground(Void... voids) {
        PhotosReader PR = new PhotosReader();
        images = PR.getPhotosArray(mContext);
        PhotosModifier PM = new PhotosModifier();
        ArrayList<Bitmap> bitmaps = PM.getResizedPhotosBitmap(images);
        return bitmaps;
    }

    @Override
    protected void onPostExecute(ArrayList<Bitmap> bitmaps) {
        super.onPostExecute(bitmaps);
        views.setImageViewBitmap(R.id.imageView, bitmaps.get(0));
        views.setImageViewBitmap(R.id.imageView2, bitmaps.get(1));
        views.setImageViewBitmap(R.id.imageView3, bitmaps.get(2));
        views.setImageViewBitmap(R.id.imageView4, bitmaps.get(3));
        views.setImageViewBitmap(R.id.imageView5, bitmaps.get(4));
    }
}

更新时:

   @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // There may be multiple widgets active, so update all of them
        for (int appWidgetId : appWidgetIds) {
            updateAppWidget(context, appWidgetManager, appWidgetId);

            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.new_app_widget);
            new PhotosLoader(context, views).execute();
            Log.d("Main","onUpdate");
        }
    }

这些只是项目中的代码更改，我第一次实现 AsyncTask，所以我知道我可能做错了什么，看起来很简单

Answer 1

我认为问题在于您试图在 从 onUpdate 方法返回 RemoteView 对象后更新它。您应该返回已经构建并填写了所需数据的它。

也许尝试一种不同的方法，而不是传递位图并将 Uri 设置为 ImageView 上的图像？

编辑:实际上，另一个问题可能是您实际上并没有在任何地方更新小部件 :D 您创建了 RemoteView，然后将其删除。你在调用 appWidgetManager.updateAppWidget 吗？