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();
                }
}