AsyncTask 和Timer同时使用

package com.example.test;  import java.net.URL; import java.util.Timer; import java.util.TimerTask;  import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory;  import org.xml.sax.InputSource; import org.xml.sax.XMLReader;  import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.os.Handler; import android.util.Log;  public class MyXmlPoller extends Activity {      private Handler handler = new Handler();      @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);          new Timer().schedule(new MyTimerTask(), 0, 1000);     }      private class MyAsyncTask extends AsyncTask {          protected MyData doInBackground(Integer... counter) {             MyData myData = new MyData();              try {                 URL url = new URL("http://www.example.com/my.xml");                 SAXParserFactory spf = SAXParserFactory.newInstance();                 SAXParser sp = spf.newSAXParser();                  XMLReader xr = sp.getXMLReader();                  MySAXHandler mySAXHandler = new Handler();                 xr.setContentHandler(mySAXHandler);                  xr.parse(new InputSource(url.openStream()));                  myData = mySAXHandler.getParsedData();                  return myData;              } catch (Exception e) {                 Log.e("!!!!!!!!!! MyAsyncTask doInBackground error", e.getMessage(), e);                 return myData;             }          }          protected void onPostExecute(MyData myData) {             Log.d("+++++++++++++ MyAsyncTask onPostExecute", myData.toString());         }     } // MyAsyncTask     private Handler mHandler = new Handler();   public class MyTimerTask extends TimerTask {     public void run() {         mHandler.post(             new Runnable() {                  public void run() {                      new MyAsyncTask().execute("");                 }              };              )     } } }

在这里呢一定要注意TimerTask要运行在Handler中。

当然上面的代码也可以如下变化

URL url = new URL("http://www.example.com/my.xml");             SAXParserFactory spf = SAXParserFactory.newInstance();             SAXParser sp = spf.newSAXParser();              XMLReader xr = sp.getXMLReader();              MyHandler myHandler = new MyHandler();             xr.setContentHandler(myHandler);

将上面的放在onPreExecute() method 中。

http://developer.android.com/intl/fr/reference/android/os/Looper.html

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