java - 安卓 : Updating UI components from async class

Question

我有 UI 组件，其中有由 ImageView 组成的表格，现在我想从 URL 设置图像。

现在，当我尝试异步调用图像设置为 UI 的其他类时，它会给出错误:UI 只能由 UI 线程更新。我想加载 UI 并在图像可用时加载图像。

这是我的代码:

Calling function...
    new AsyncImageLoader(context,imgviewArray).execute();

//    Called class..
        @Override
        protected Void doInBackground(Void... urls) {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
            int i = 0;

            try{
                db=new MyDB(mainact_instance);
                System.out.println("Inside doInBackground");

                if(isNetworkAvailable())
                {
                    System.out.println("Network connected");
                    System.out.println("Fetching from network-Images");
                    Movie[] movies = db.selectRecords();
                    for(Movie mv : movies)
                    {
                        try {
                            URL url = new URL(IMAGE_URL+mv.getId()+".jpg");
                            Bitmap bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
                            images[i].setImageBitmap(bmp);
                            i++;
                        } catch (Exception e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } 
                    }

                }

                else{
                    System.out.println("Network not connected..fetching max id row");
                }
            }catch(Exception ex){ex.printStackTrace();
            }
            return null;
            //db.close();       
        }

请告诉我如何实现这一目标？

Answer 1

将 UI 线程相关代码移至 onPostExecute || onProgressUpdate

例如:

protected void onPostExecute(Long result) {

 // after finishing fetching your image from URL, update the ImageView here
 images[i].setImageBitmap(bmp);
}

我可以看到您正在AsyncTask中下载多个图像，然后您可以使用PublishProgress您需要更新您的AsyncTask定义以允许将位图传递给publishProgress方法，如下所示:

AsyncTask<whatever..., Bitmaps, whatever...>() 

然后

publishProgress(yourBitmapObject);

protected void onProgressUpdate(Bitmap[] values) {
  images[i].setImageBitmap(values[0]);
};