我一直在浏览android开发者文档，试图弄清楚如何获取当前位置，特别是https://developer.android.com/training/location/retrieve-current.html
当我在android中创建一个新项目并选择Map模板时，onCreate方法中有代码，然后还有一个onMapReady方法。
首先，只是确认以下代码将地图放在屏幕上？如果是这样，onMapReady只是一种允许操作地图的方法吗？
SupportMapFragment mapFragment = (SupportMapFragment) etSupportFragmentManager()
.findFragmentById(R.id.map); mapFragment.getMapAsync(this);
在文档中：获取当前位置信息re：构建到GoogleApiClient，例如
// Create an instance of GoogleAPIClient.
if (mGoogleApiClient == null) {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
文档中指定的其他方法是onStart，onStop和onConnected。这一切都有意义，但要制作一个非常基本的获取当前位置应用程序，我仍然使用SupportMapFragment mapFragment =（SupportMapFragment）....从onCreate内生成地图？是否还需要onMapReady函数？创建GoogleApiClient实例的最佳位置在哪里？
在随后的文档页面上，还提供了有关在与
连接后获取当前位置设置的信息 LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder()
.addLocationRequest(mLocationRequest);
但我不确定应该在哪里定义。
最后，在Android Studio的Map模板中，默认类定义为：
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback
但在谷歌文档中，它被定义为：
公共类MainActivity扩展了ActionBarActivity实现 ConnectionCallbacks，OnConnectionFailedListener
该类延伸的活动是否重要？
感谢。
答案 0 :(得分：3)
我使用了预定义的地图活动。您可以通过它获取最后一个已知的当前位置。
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private GoogleMap mMap;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;
LocationRequest mLocationRequest;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
checkLocationPermission();
}
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
//Initialize Google Play Services
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
buildGoogleApiClient();
mMap.setMyLocationEnabled(true);
}
}
else {
buildGoogleApiClient();
mMap.setMyLocationEnabled(true);
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
@Override
public void onConnected(Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onLocationChanged(Location location) {
mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
//Place current location marker
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(latLng);
markerOptions.title("Current Position");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
mCurrLocationMarker = mMap.addMarker(markerOptions);
//move map camera
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mMap.animateCamera(CameraUpdateFactory.zoomTo(11));
//stop location updates
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
public boolean checkLocationPermission(){
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Asking user if explanation is needed
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.ACCESS_FINE_LOCATION)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
//Prompt the user once explanation has been shown
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
return false;
} else {
return true;
}
}
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted. Do the
// contacts-related task you need to do.
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient == null) {
buildGoogleApiClient();
}
mMap.setMyLocationEnabled(true);
}
} else {
// Permission denied, Disable the functionality that depends on this permission.
Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show();
}
return;
}
// other 'case' lines to check for other permissions this app might request.
// You can add here other case statements according to your requirement.
}
}
}
在Android Manifest中允许网络状态权限和位置权限
答案 1 :(得分：2)
如果您的要求只是获取用户的当前位置，那么您不需要使用MapActivity，您可以依赖LocationServices并要求 getLastLocation 。这是以下示例代码，为您提供服务目的
// Create an instance of GoogleAPIClient.
if (mGoogleApiClient == null) {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
由于您已经实现了GoogleApiClient的侦听器，因此您可以询问位置，如下面的代码所示：
@Override
public void onConnected(Bundle bundle) {
Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
startLocationUpdates();
}
protected void startLocationUpdates() {
Log.d(TAG, "startLocationUpdates--> Start Location Updates");
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);
}
public void stopLocationUpdates() {
Log.d(TAG,"stopLocationUpdates--> Stop location updates");
LocationServices.FusedLocationApi.removeLocationUpdates(
mGoogleApiClient, this);
stopService();
}
@Override
public void onConnectionSuspended(int i) {
Log.i(TAG, "Connection suspended");
mGoogleApiClient.connect();
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = " +
connectionResult.getErrorCode());
}
@Override
public void onLocationChanged(Location location) {
Log.d(TAG, "onLocationChanged--> Location is " + location.toString());
mCurrentLocation = location;
}
此外，如果您希望在定期间隔后跟踪位置，则可以从 OnCreate （您创建GoogleApiClient的对象）中创建 locationRequest 对象：
protected void createLocationRequest() {
Log.d(TAG,"createLocationRequest--> Create Location Request");
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10 * 1000); //UPDATE_INTERVAL_IN_MS
mLocationRequest.setFastestInterval(5 * 1000); //FASTEST_UPDATE_INTERVAL_IN_MS
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
}
这是startLocation更新方法：
protected void startLocationUpdates() {
Log.d(TAG, "startLocationUpdates--> Start Location Updates");
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);
}
我希望这可以回答你的问题，如果能解决你的问题，请将其标记为答案。