Asynctask實現LocationListener：onLocationChanged從未調用

Question

我做了一個簡單的代碼，允許用戶在按某個按鈕時獲取當前的GPS位置。 因此，我創建了一個MainActivity和一個Asynctask類，Asynctask實現了LocationListener，但重載onLocationChanged永遠不會調用！ （沒有在LogCat跟蹤） 然後，我得到的GPS數據，但他從來沒有改變時，我按下按鈕：/

如果我離開應用程序，如果我強制processus退出參數選項Android和我再次啓動我的應用程序，GPS數據保持不變。我不明白，以及爲什麼重寫方法永遠不會被調用。

這裏我唯一的文件：

公共類MainActivity擴展活動{

public static Context context; 
    public Button push = null; 
    public getGPS tache_getGPS = null; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     context = getApplication().getApplicationContext(); 

     push = (Button) findViewById(R.id.button); 
     push.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       Log.i("T: onClick", "debut"); 
       tache_getGPS = new getGPS(); 
       tache_getGPS.execute(); 
       Log.i("T: onClick", "fin"); 
       // TODO Auto-generated method stub 
      } 
     }); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

} 

class getGPS extends AsyncTask<Void, Integer, Location> implements 
     LocationListener { 

    final long REFRESH = 5 * 1000; 
    private Location location; 
    private LocationManager lm; 

    protected void onPreExecute() { 
     Log.i("T: onPreExcute", "debut"); 
     Criteria crit = new Criteria(); 
     crit.setAccuracy(Criteria.ACCURACY_FINE); 

     // Configure location manager - I'm using just the network provider in 
     // this example 
     lm = (LocationManager) MainActivity.context 
       .getSystemService(Context.LOCATION_SERVICE); 

     String best = lm.getBestProvider(crit, false); 
     Log.i("T: onPreExecute", "best : " + best); 

     lm.requestLocationUpdates(best, 0, 1, this); 
     location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER); 
     // nearProgress.setVisibility(View.VISIBLE); 
     Log.i("T: onPreExcute", "fin"); 
    } 

    protected Location doInBackground(Void... params) { 
     Log.i("T: doInBackground", "debut"); 

     // Try to use the last known position 
     Location lastLocation = lm 
       .getLastKnownLocation(LocationManager.GPS_PROVIDER); 
       /* 
     // If it's too old, get a new one by location manager 
     if (System.currentTimeMillis() - lastLocation.getTime() > REFRESH) { 
      while (location == null) 
       try { 
        Thread.sleep(100); 
       } catch (Exception ex) { 
       } 

      return location; 
     } 
       */ 
     Log.i("T: doInBackground", "fin"); 
     return lastLocation; 
    } 

    protected void onPostExecute(Location location) { 
     Log.i("T: onPostExecute", "debut"); 
     // nearProgress.setVisibility(View.GONE); 

     lm = (LocationManager) MainActivity.context 
       .getSystemService(Context.LOCATION_SERVICE); 
     lm.removeUpdates(this); 

     Log.i("T: onPostExecute", 
       "Altitude : " + String.valueOf(location.getAltitude())); 
     Log.i("T: onPostExecute", 
       "Longitude : " + String.valueOf(location.getLongitude())); 
     Log.i("T: onPostExecute", 
       "Latitude : " + String.valueOf(location.getLatitude())); 
     Log.i("T: onPostExecute", 
       "Precision(mètre) : " + String.valueOf(location.getAccuracy())); 
     Log.i("T: onPostExecute", "fin"); 

     Toast.makeText(
       MainActivity.context, 
       "Altitude : " + String.valueOf(location.getAltitude()) + "\n" 
         + "Longitude : " 
         + String.valueOf(location.getLongitude()) + "\n" 
         + "Latitude : " 
         + String.valueOf(location.getLatitude()) + "\n" 
         + "Precision(mètre) : " 
         + String.valueOf(location.getAccuracy()), 
       Toast.LENGTH_SHORT).show(); 

     return; 
    } 

    @Override 
    public void onLocationChanged(Location newLocation) { 
     Log.i("T: onLocationChanged", "debut"); 
     location = newLocation; 
     Log.i("T: onLocationChanged", "fin"); 
    } 

    @Override 
    public void onProviderDisabled(String provider) { 
     Log.i("T: onProviderDisabled", provider); 
    } 

    @Override 
    public void onProviderEnabled(String provider) { 
     Log.i("T: onProviderEnabled", provider); 
    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 
     Log.i("T: onStatusChanged", "provider : " + provider); 
     Log.i("T: onStatusChanged", "status : " + status); 
     Log.i("T: onStatusChanged", "extras : " + extras.toString()); 
    } 

} 

感謝您的幫助，爲我可憐的英語寫作X對不起）

NEW CODE（建議以後=） ），沒有Asinctask

public class MainActivity extends Activity implements LocationListener{ 

    public static Context context; 
    public Button push = null; 
    public getGPS tache_getGPS = null; 

    private Location location; 
    private LocationManager lm; 
    final long REFRESH = 5 * 1000; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     context = getApplication().getApplicationContext(); 

     push = (Button) findViewById(R.id.button); 
     push.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       Log.i("T: onClick", "debut"); 
       location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER); 
       Location lastLocation = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER); 
       if (System.currentTimeMillis() - lastLocation.getTime() > REFRESH) { 
        while (location == null) 
         try { Thread.sleep(100); } catch (Exception ex) { } 
        Log.i("FINAL : location", location.toString()); 
        Toast.makeText(MainActivity.context, "location : "+location.toString(), Toast.LENGTH_SHORT).show(); 
        return; 
       } 
       Log.i("FINAL : lastlocation", lastLocation.toString()); 
       Toast.makeText(MainActivity.context, "lastLocation : "+lastLocation.toString(), Toast.LENGTH_SHORT).show(); 
       Log.i("T: onClick", "fin"); 
      } 
     }); 
    } 

    @Override 
    protected void onResume(){ 
     super.onResume(); 
     Criteria crit = new Criteria(); 
     crit.setAccuracy(Criteria.ACCURACY_FINE); 
     lm = (LocationManager) MainActivity.context.getSystemService(Context.LOCATION_SERVICE); 

     String best = lm.getBestProvider(crit, false); 
     Log.i("T: onPreExecute", "best : " + best); 

     lm.requestLocationUpdates(best, 1, 1, this); 
    } 

    @Override 
    protected void onPause(){ 
     super.onPause(); 
     lm.removeUpdates(this); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    @Override 
    public void onLocationChanged(Location newLocation) { 
     Toast.makeText(context, "onLocationChanged", Toast.LENGTH_SHORT).show(); 
     Log.i("T: onLocationChanged", "debut"); 
     location = newLocation; 
     Log.i("T: onLocationChanged", "fin"); 
    } 

    @Override 
    public void onProviderDisabled(String provider) { 
     Log.i("T: onProviderDisabled", provider); 
    } 

    @Override 
    public void onProviderEnabled(String provider) { 
     Log.i("T: onProviderEnabled", provider); 
    } 

    @Override 
    public void onStatusChanged(String provider, int status, Bundle extras) { 
     Log.i("T: onStatusChanged", "provider : " + provider); 
     Log.i("T: onStatusChanged", "status : " + status); 
     Log.i("T: onStatusChanged", "extras : " + extras.toString()); 
    } 

} 

Answer 1

在requestLocationUpdates y ou指定1作爲minDistance（minDistance是通知的最小距離間隔，以米爲單位）。嘗試將其設置爲0.