AsyncTask的使用

 

 class   DownloadImagesTask  extends   AsyncTask<String, Integer, Bitmap> {

 private    int   imageViewID;

      protected    void   onPostExecute(Bitmap bitmap1) {
     setImage(imageViewID, bitmap1);
 }

      public    void   setImageId( int   imageViewID) {
          this  .imageViewID = imageViewID;
     }

      @Override
      protected   Bitmap doInBackground(String... url) {
         Bitmap bitmap1 =
             DownloadImage(url[ 0  ]);
          return   bitmap1;
     }


 /* 39.        @Override
 }   //有很多的方法可以用

 

 DownloadImagesTask task1 =  new   DownloadImagesTask();
 task1.setImageId(R.id.img1);
 task1.execute( "http://assets.devx.com/articlefigs/39810_1.jpg" );

 

 private   Bitmap DownloadImage(String URL)
    {
        Bitmap bitmap =  null  ;
        InputStream in =  null  ;
         try   {
            in = OpenHttpConnection(URL);
            bitmap = BitmapFactory.decodeStream(in);
            in.close();
        }  catch   (IOException e1) {
             // TODO Auto-generated catch block
            e1.printStackTrace();
        }
         return   bitmap;
    }

 在其中使用进度对话框

 

 class   GetTask  extends   AsyncTask<Object, Void, String>
     {
         Context mContext;
             ProgressDialog mDialog =  null  ;

             GetPhotoFeedTask(Context context)
     {
         mContext = context;
     }

          @Override
          protected    void   onPreExecute()
         {
              super  .onPreExecute();

              mDialog =  new   ProgressDialog(mContext);
              mDialog.setMessage( "Please wait..." );
              mDialog.show();
         }
                  @Override
          protected   String doInBackground(Object... params)
         {
                    // do stuff in background : fetch response
                 }

                  @Override
          protected    void   onPostExecute(String result)
         {
              super  .onPostExecute(result);
             setProgressBarIndeterminateVisibility( false  );
              // mDialog.dismiss();
                 }
 }