Android uses AsyncTask to download pictures and display progress bar function

public class AsyncTaskActivity2 extends Activity { 
 private Button btnDown;//Picture frame private ImageView ivImage;//Picture URL private static String image_path = "/page/main1406/images/"; 
 //Progress dialog private ProgressDialog dialog; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  (savedInstanceState); 
  setContentView(.asynctask_activity); 
  btnDown = (Button) findViewById(); 
  ivImage = (ImageView) findViewById(); 
  // Create a new dialog box and will not be displayed  dialog = new ProgressDialog(this); 
  ("hint"); 
  ("Downloading, please wait..."); 
  (ProgressDialog.STYLE_HORIZONTAL);//With horizontal scroll bar  (false);//cannot  // After clicking the button, execute AsyncTask and pass in the image URL  (new () { 
   @Override 
   public void onClick(View v) { 
    // Execute asynchronous tasks    new MyTask().execute(image_path);//Start AsyncTask, the parameter type is the type of the first parameter of the asynchronous class   } 
  }); 
 } 
 //Create an internal class to download pictures public class MyTask extends AsyncTask<String, Integer, Bitmap> { 
  @Override 
  protected void onPreExecute() {//Open the asynchronous class first after starting it, you can set it   (); 
   ();//Show dialog box  } 
   //Step 2, generally complicated processing  @Override 
  protected Bitmap doInBackground(String... params) {//The most important thing is to process complexly, backend, receive parameters transmitted from execute   Bitmap bitmap = null; //Binary pictures   //Byte array output stream   ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); 
   InputStream inputStream = null;//Byte input stream   try { 
    HttpClient httpClient = new DefaultHttpClient();//Create an Http client    HttpGet httpGet = new HttpGet(params[0]);//Send a request    HttpResponse httpResponse = (httpGet);//return    if (().getStatusCode() == 200) {//success     inputStream = ().getContent();//Get the return content as input stream     long file_length = ().getContentLength();//File length     int len = 0; 
     byte[] data = new byte[1024];//Bytes read each time     int total_length = 0; 
     // Read image data in bytes     while ((len = (data)) != -1) { 
      total_length += len; 
      // Calculate progress      int values = (int) ((total_length / (float) file_length) * 100); 
      // Release progress information      publishProgress(values);//Release progress, AsyncTask's second parameter type triggers onProgressUpdate update progress bar      (data, 0, len);//Write output stream     } 
     byte[] result=();//Convert the byte array output stream to byte array     //Generate binary pictures     bitmap=(result, 0, ); 
    } 
   } catch (Exception e) { 
    (); 
   } finally { 
    try { 
     if (inputStream != null) { 
      (); 
     } 
    } catch (Exception e2) { 
    } 
   } 
   return bitmap; 
  } 
  // When there is data sent by publishProgress(value) triggered, update the UI  @Override 
  protected void onProgressUpdate(Integer... values) { 
   (values); 
   // Set the progress value of the progress dialog box   (values[0]);//Update progress bar, run in UI  } 
  //Step 4  @Override 
  protected void onPostExecute(Bitmap result) {//Hide the dialog box after downloading   (result); 
   (); 
   (result); //Update the UI, display the picture, run in the UI  } 
 } 
}