android asyncTask的使用

public class MainActivity extends Activity {

Dialog _da;

public static final int PROGRESS_H = 0;

@Override
public void onCreate(Bundle bd){
super.onCreate(bd);
setContentView(R.layout.main);
AsyncTaskTest att = new AsyncTaskTest();
att.execute(this);
}

@Override
public Dialog onCreateDialog(int id){
switch(id){
case PROGRESS_H:
_da = new ProgressDialog(this);
((ProgressDialog)_da).setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
((ProgressDialog)_da).setTitle("这是一个测试");
break;
}
return _da;
}

class AsyncTaskTest extends AsyncTask<Activity,Integer,Long>{
@Override
public void onPreExecute(){
showDialog(PROGRESS_H);
}
@Override
public Long doInBackground(Activity...activities){
Long a = 0l;
int aa = 0;
publishProgress(aa);
return a;
}
@Override
public void onProgressUpdate(Integer...integers){
((ProgressDialog)_da).setProgress(integers[0]);
}
@Override
public void onPostExecute(Long result){
  Toast.makeText(getApplication(), "测试完成", Toast.LENGTH_SHORT).show();
}
}
}