我从服务启动的线程请求位置更新时遇到问题。
我的应用程序需要从后台服务获取位置更新（没有任何 UI 线程）。我将解释我的应用程序的结构。
onStartCommand()服务中，它启动一个调度线程。问题是当调度程序调用locationMgr.requestLocationUpdates()
它说Can't create handler inside thread that has not called Looper.prepare()
我已经看到其他人的类似问题但找不到任何解决方案。我听说我们可以直接从服务调用以获取位置更新而没有任何问题，但由于我找不到让服务休眠的方法（如调度程序线程），我想我需要一个单独的线程。
请解释为什么会这样？android 是否需要 UI 线程来请求位置？通过更改我的应用程序结构有什么解决方案吗？
Looper is what keeps polling a thread queue for Message's/Runnables (those posted via a Handler on that thread). UI thread has one by default. For custom threads, you need to set it up before you start the thread.
Class used to run a message loop for a thread. Threads by default do not have a message loop associated with them; to create one, call prepare() in the thread that is to run the loop, and then loop() to have it process messages until the loop is stopped.
Now, RequestLocationUpdates() needs a mechanism to deliver updates to your thread, but your thread doesn't have a Looper polling.
Consider Moving RequestLocationUpdates() and its corresponding removeUpdates() to Service thread. Most likely where service starts and stops.
我已经使用了它并且工作正常：获取服务位置
这里的服务等级：
public class MyService extends Service {
@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();
}
@Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
}
@Override
public void onStart(Intent intent, int startId) {
// TODO Auto-generated method stub
super.onStart(intent, startId);
// start location manager
LocationDetermined objLocationDetemined = new LocationDetermined(this);
objLocationDetemined.getlocation(this);
objLocationDetemined.getRecentKnownLocation(this);
}
位置类在这里：
public class LocationDetermined implements OnInitListener {
String TAG = "LocationDeterminedClass";
private static LocationManager locationManager;
double Lat = 0.0;
double Long = 0.0;
GeoPoint geoPoint;
private Toast mToast;
Context appContext;
static MyLocationListener locationListener;
public LocationDetermined(Context context) {
this.appContext = context;
}
public MyLocationListener getlocation(Context appContext) {
locationManager = (LocationManager) appContext
.getSystemService(Context.LOCATION_SERVICE);
locationListener = new MyLocationListener();
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_COARSE);
String provider = locationManager.getBestProvider(criteria, true);
Log.d(TAG, "------provider------" + provider);
if (provider != null && locationManager.isProviderEnabled(provider)) {
locationManager.requestLocationUpdates(provider, 0, 0,
locationListener);
} else {
Toast.makeText(appContext, "No provider available to get loctaion",
2000).show();
}
return locationListener;
}
private class MyLocationListener implements LocationListener {
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
public void onLocationChanged(final Location argLocation) {
// TODO Auto-generated method stub
if (argLocation != null) {
Lat = argLocation.getLatitude();
Long = argLocation.getLongitude();
Log.e("OnLocationChanged:", "lat:" + Lat + " long:" + Long);
Log.d("service gps", "lat" + argLocation.getLatitude() + "-"
+ argLocation.getLongitude());
Constant.mLatitude = argLocation.getLatitude();
Constant.mLongitude = argLocation.getLongitude();
}
}
}
public GeoPoint getRecentKnownLocation(Context appContext) {
Location locGps = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
Location locNet = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
Location locPassive = locationManager
.getLastKnownLocation(LocationManager.PASSIVE_PROVIDER);
if (locGps != null) {
Lat = locGps.getLatitude();
Long = locGps.getLongitude();
Constant.mLatitude = locGps.getLatitude();
Constant.mLongitude = locGps.getLongitude();
geoPoint = new GeoPoint((int) (Lat * 1000000),
(int) (Long * 1000000));
return geoPoint;
} else if (locNet != null) {
Lat = locNet.getLatitude();
Long = locNet.getLongitude();
Constant.mLatitude = locNet.getLatitude();
Constant.mLongitude = locNet.getLongitude();
geoPoint = new GeoPoint((int) (Lat * 1000000),
(int) (Long * 1000000));
return geoPoint;
}
return geoPoint;
}
private void fetchedSavedLocationDetail(Context mContext) {
}
@Override
public void onInit(int status) {
// TODO Auto-generated method stub
}
public static void removeLocationListener() {
locationManager.removeUpdates(locationListener);
}
}
我在常量类中使用这些变量来存储位置 public static double mLatitude = 0.0, mLongitude = 0.0;
启动服务 startService(new Intent(this, MyService.class));
发生的原因是：getLooper 连接到 context 的 UI，但是 service 是 ackground 进程没有直接连接到 UI。所以你得到错误。
您的问题的解决方案：
1）将位置类放在其他包中。2）导入该包名称。3) 在你的包中使用一个回调接口。4）在你的服务组件中使用接口实例。5）它会工作！
我已经通过使用处理程序修复了它。
handleMessage()handleMessage()包含实际调度程序循环的