AsyncTask实例

public class MainActivity extends Activity { private TextView show; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.activity_main); show= (TextView) findViewById(R.id.show);

} public void download(View source) throws MalformedURLException{ DownTask task=new DownTask(this); task.execute(new URL("http://www.crazyit.org/ethos.php")); } class DownTask extends AsyncTask<URL,Integer,String> { ProgressDialog pdialog; int hasRead=0; Context mContext; public DownTask(Context ctx) { mContext = ctx; }

//子线程，执行耗时操作 @Override protected String doInBackground(URL… params) { StringBuilder sb = new StringBuilder(); try { URLConnection conn=params[0].openConnection(); BufferedReader br= new BufferedReader(new InputStreamReader(conn.getInputStream(),”utf-8”)); String line=null; while ((line=br.readLine())!=null){//br.readline:下一行 sb.append(line+”\n”); hasRead++; publishProgress(hasRead); } return sb.toString(); } catch (IOException e) { e.printStackTrace(); } return null; }

@Override protected void onPostExecute(String result) { show.setText(result); pdialog.dismiss(); }

//主线程 @Override protected void onPreExecute() { pdialog=new ProgressDialog(mContext); pdialog.setTitle(“任务正在执行中”); pdialog.setMessage(“敬请等待…”); pdialog.setCancelable(false); pdialog.setMax(202); pdialog.setIndeterminate(false); pdialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); pdialog.show(); } //主线程 @Override protected void onProgressUpdate(Integer… values) { show.setText(“已经读取了[“+values[0]+”]行!”); pdialog.setProgress(values[0]); } } }