我制作了一个简单的代码，允许用户在按下某个按钮时获取他当前的 GPS 位置。所以，我创建了一个 MainActivity 和一个 Asynctask 类，Asynctask 实现了 LocationListener 但永远不会调用覆盖 onLocationChanged ！（LogCat 中没有任何痕迹..）然后，我得到 gps 数据，但当我按下按钮时他从未改变：/
如果我离开应用程序，如果我强制进程退出参数选项 Android 并再次启动我的应用程序，gps 数据保持不变。我不明白..为什么永远不会调用覆盖方法。
这是我唯一的文件：
公共类 MainActivity 扩展 Activity {
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());
}
}
感谢您的帮助，并为我糟糕的英语写作感到抱歉 x)
新代码（在建议 =) 之后），没有 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());
}
}