我正在用 Java 编写一个 Android 应用程序。该活动包含一个谷歌地图，我想要的是在顶部有一个按钮位置，如图所示：
我希望当我单击该位置以指向我当前的位置时，我正在使用FusedLocationProviderClient类。
当我运行程序时，一切都很好，直到我按顺序执行以下步骤：1-第一次运行应用程序，我拒绝权限 2-第二次运行应用程序。它再次请求权限，所以我回答好，但按钮没有出现。3-我关闭了应用程序，因为我上次对位置许可说是，所以按钮在地图上并且正在工作。
这是我的代码：
private void checkPermissions(int fineLocationPermission) {
if (fineLocationPermission != PackageManager.PERMISSION_GRANTED) { //If we don't have any permissions yet
// TODO: Consider calling
//We have to request permissions and in case the user refuse the permission we show an explanation of why he needs the permission
//The following method returns true in case the user reject the permission
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
PERMISSION_REQUEST_CODE);
} else
mLocationPermissionGranted=true;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode) {
case PERMISSION_REQUEST_CODE:
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//If the user accepts the dialog box then we get the last location and show button
mLocationPermissionGranted=true;
} else {
mLocationPermissionGranted=false;
// permission denied, boo! Disable the
// functionality that depends on this permission.
Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show();
}
}
}
public void onLocationChanged(final Location location) {
String msg = "Updated location: " +
Double.toString(location.getLatitude()) + ", " +
Double.toString(location.getLongitude());
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
final LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
//Show button to locate current position
mMap.setOnMyLocationButtonClickListener(new GoogleMap.OnMyLocationButtonClickListener() {
@Override
public boolean onMyLocationButtonClick() {
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
CameraUpdateFactory.newLatLngZoom(latLng,12);
//mMap.setMaxZoomPreference(12);
return false;
}
});
// Add a marker our current position
LatLng CurrentPosition = new LatLng(location.getLatitude(), location.getLongitude());
mMap.addMarker(new MarkerOptions().position(CurrentPosition).title("Here you are!"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(CurrentPosition));
}
@Override
public void onMapReady(GoogleMap googleMap) {
//Create the map
mMap = googleMap;
//Set the type of the map: HYBRID, NORMAL, SATELLITE or TERRAIN. In our case TERRAIN type
mMap.setMapType(GoogleMap.MAP_TYPE_TERRAIN);
//Set the zoom
mMap.setMaxZoomPreference(12);
//Set the markers
MarkerOptions markerOptions= new MarkerOptions();
//Checking permissions with the permissions we have included in the manifiest
checkPermissions(permissionCheckFineLocation);
if (mLocationPermissionGranted) {
try {
mMap.setMyLocationEnabled(true);
//Last location task
Task<Location> locationResult = mFusedLocationClient.getLastLocation();
locationResult.addOnSuccessListener(this, new OnSuccessListener<Location>() {
@Override
public void onSuccess(Location location) {
//Got last known location. In some rare situations this can be null
if (location != null) {
//Logic to handle location object
onLocationChanged(location);
}
}
});
} catch (SecurityException e) {
Log.e("error", e.getMessage());
}
}
}
我知道这是一个奇怪的问题，但我不知道如何表达自己。任何帮助都会很棒！先感谢您！