如何使用AsyncTask从Url设置图像？

Question

我是一个新手程序员,我正在制作一个Android程序,在给定的URL上显示ImageView上的图像.我的问题是你如何在AsyncTask上使用它？

这些代码适用于最小的SDK 2.2,但我切换到min SDK 3.0,因此它需要在AsyncTask上运行.谢谢您的帮助!:)

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    satellite(); //satellite's image from main menu

}

//******satellite url
private void satellite() {
    // TODO Auto-generated method stub
    ImageView imgView =(ImageView)findViewById(R.id.satellite);
    Drawable drawable = LoadImageFromWeb("http://www.pagasa.dost.gov.ph/wb/sat_images/satellite.gif");
    imgView.setImageDrawable(drawable);        
}

private Drawable LoadImageFromWeb(String url){
      try{
          InputStream is = (InputStream) new URL(url).getContent();
          Drawable d = Drawable.createFromStream(is, "src name");
          return d;
      }catch (Exception e) {
          System.out.println("Exc="+e);
          return null;
      }
}

Answer 1

如果图像不是那么大，您可以使用匿名类来执行异步任务。这会喜欢这样：

ImageView mChart = (ImageView) findViewById(R.id.imageview);
String URL = "http://www...anything ...";

mChart.setTag(URL);
new DownloadImageTask.execute(mChart);

任务类别是

public class DownloadImagesTask extends AsyncTask<ImageView, Void, Bitmap> {
   ImageView imageView = null;
   @Override
   protected Bitmap doInBackground(ImageView... imageViews) {
      this.imageView = imageViews[0];
      return download_Image((String)imageView.getTag());
   }

   @Override
   protected void onPostExecute(Bitmap result) {
      imageView.setImageBitmap(result);
   }

   private Bitmap download_Image(String url) {
       ...
   }