Android服务，定期HTTP请求

Question

我正在开发一项服务来显示我将要通过访问数据库的PHP页面的通知。我想开发一个页面本身的定期检查..我做的活动没有任何问题，但服务应用程序崩溃或无法访问网页。怎么会这样？这是我现在使用的代码：

@SuppressLint("NewApi") public class MyService extends Service {

@Override
 public void onCreate() {   

     super.onCreate();      
 }

 @Override
 public void onDestroy() {      

     super.onDestroy();         
 }

 @Override
 public int onStartCommand(Intent intent, int flags, int startId) {     

        HttpClient httpclient = new DefaultHttpClient(); // Create HTTP Client
        HttpGet httpget = new HttpGet("http://zackfairsite.altervista.org/test_notifica.php"); // Set the action you want to do
        HttpResponse response = httpclient.execute(httpget); // Executeit
        HttpEntity entity = response.getEntity(); 
        InputStream is = entity.getContent(); // Create an InputStream with the response
        BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) // Read line by line
            sb.append(line + "\n");

        String resString = sb.toString(); // Result is here

        is.close(); // Close the stream

         Toast.makeText(this, resString, Toast.LENGTH_LONG).show();                       

     return super.onStartCommand(intent, flags, startId);

 }

 @Override
 public IBinder onBind(Intent arg0) {       
     return null;
 }  

}