我按照写的内容 this link, 此链接是developer.android.com上的一篇文章，它描述并解释了如何通过Class LocationClient获取用户的位置。 我按照说明操作，但是我在地图上添加了一个标记，并专注于我所获得的位置。 当我尝试运行应用程序时，我收到一条消息，表明应用程序的操作已停止。 我对代码进行了解释，我认为问题在于函数
getMyLocation()
我错过了什么？如果你能帮助我，我会很高兴的。 以下是完整代码：
package ebookfrenzy.com.mapdemo;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentSender;
import android.location.Location;
import android.os.Bundle;
import android.provider.Settings;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesClient;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.location.LocationClient;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.UiSettings;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapDemoActivity extends FragmentActivity implements
GooglePlayServicesClient.ConnectionCallbacks,
GooglePlayServicesClient.OnConnectionFailedListener {
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
LocationClient mLocationClient;
LatLng latLngOfMyLocation;
// Global constants
/*
* Define a request code to send to Google Play services
* This code is returned in Activity.onActivityResult
*/
private final static int
CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
// Define a DialogFragment that displays the error dialog
public static class ErrorDialogFragment extends DialogFragment {
// Global field to contain the error dialog
private Dialog mDialog;
// Default constructor. Sets the dialog field to null
public ErrorDialogFragment() {
super();
mDialog = null;
}
// Set the dialog to display
public void setDialog(Dialog dialog) {
mDialog = dialog;
}
// Return a Dialog to the DialogFragment.
public Dialog onCreateDialog(Bundle savedInstanceState) {
return mDialog;
}
}
/*
* Handle results returned to the FragmentActivity
* by Google Play services
*/
@Override
protected void onActivityResult(
int requestCode, int resultCode, Intent data) {
// Decide what to do based on the original request code
switch (requestCode) {
case CONNECTION_FAILURE_RESOLUTION_REQUEST :
/*
* If the result code is Activity.RESULT_OK, try
* to connect again
*/
switch (resultCode) {
case Activity.RESULT_OK :
/*
* Try the request again
*/
break;
}
}
}
private boolean servicesConnected() {
// Check that Google Play services is available
int resultCode =
GooglePlayServicesUtil.
isGooglePlayServicesAvailable(this);
// If Google Play services is available
if (ConnectionResult.SUCCESS == resultCode) {
// In debug mode, log the status
Log.d("Location Updates",
"Google Play services is available.");
// Continue
return true;
// Google Play services was not available for some reason.
// resultCode holds the error code.
} else {
// Get the error dialog from Google Play services
Dialog errorDialog = GooglePlayServicesUtil.getErrorDialog(
resultCode,
this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
// If Google Play services can provide an error dialog
if (errorDialog != null) {
// Create a new DialogFragment for the error dialog
ErrorDialogFragment errorFragment =
new ErrorDialogFragment();
// Set the dialog in the DialogFragment
errorFragment.setDialog(errorDialog);
// Show the error dialog in the DialogFragment
errorFragment.show(getSupportFragmentManager(),
"Location Updates");
}
}
return false;
}
/*
* Called by Location Services when the request to connect the
* client finishes successfully. At this point, you can
* request the current location or start periodic updates
*/
public void onConnected(Bundle dataBundle) {
// Display the connection status
Toast.makeText(this, "Connected", Toast.LENGTH_SHORT).show();
}
/*
* Called by Location Services if the connection to the
* location client drops because of an error.
*/
public void onDisconnected() {
// Display the connection status
Toast.makeText(this, "Disconnected. Please re-connect.",
Toast.LENGTH_SHORT).show();
}
/*
* Called by Location Services if the attempt to
* Location Services fails.
*/
public void onConnectionFailed(ConnectionResult connectionResult) {
/*
* Google Play services can resolve some errors it detects.
* If the error has a resolution, try sending an Intent to
* start a Google Play services activity that can resolve
* error.
*/
if (connectionResult.hasResolution()) {
try {
// Start an Activity that tries to resolve the error
connectionResult.startResolutionForResult(
this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
/*
* Thrown if Google Play services canceled the original
* PendingIntent
*/
} catch (IntentSender.SendIntentException e) {
// Log the error
e.printStackTrace();
}
} else {
/*
* If no resolution is available, display a dialog to the
* user with the error.
*/
showDialog(connectionResult.getErrorCode());
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map_demo);
//the message of the location service
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Make sure your location services are turned on, whether not do you want turn them on?").setPositiveButton("Yes", dialogClickListener)
.setNegativeButton("No", dialogClickListener).show();
mLocationClient = new LocationClient(this, this, this);
latLngOfMyLocation = new LatLng(getMyLocation().getLatitude(),getMyLocation().getLongitude());
setUpMapIfNeeded();
}
/*
* Called when the Activity becomes visible.
*/
@Override
protected void onStart() {
super.onStart();
// Connect the client.
mLocationClient.connect();
}
/*
* Called when the Activity is no longer visible.
*/
@Override
protected void onStop() {
// Disconnecting the client invalidates it.
mLocationClient.disconnect();
super.onStop();
}
//Setting pop-up window and is derivatives
DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
switch (which){
case DialogInterface.BUTTON_POSITIVE:
//Yes button clicked
Intent intent=new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(intent);
break;
case DialogInterface.BUTTON_NEGATIVE:
//No button clicked
break;
}
}
};
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
}
/**
* Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
* installed) and the map has not already been instantiated.. This will ensure that we only ever
* call {@link #setUpMap()} once when {@link #mMap} is not null.
* <p>
* If it isn't installed {@link SupportMapFragment} (and
* {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
* install/update the Google Play services APK on their device.
* <p>
* A user can return to this FragmentActivity after following the prompt and correctly
* installing/updating/enabling the Google Play services. Since the FragmentActivity may not
* have been completely destroyed during this process (it is likely that it would only be
* stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
* method in {@link #onResume()} to guarantee that it will be called.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
//Setting up the map settings
UiSettings mapSettings;
mapSettings = mMap.getUiSettings();
//Approval to the application to use location services
mMap.setMyLocationEnabled(true);
//lock all options built-in buttons in google maps without locking their abilities
mapSettings.setMyLocationButtonEnabled(false);
mapSettings.setZoomControlsEnabled(false);
mapSettings.setCompassEnabled(false);
/***********************************************************************************************************
LatLng MUSEUM = new LatLng(38.8874245, -77.0200729);
Marker museum = mMap.addMarker(new MarkerOptions().position(MUSEUM).title("Museum").snippet("National Air and Space Museum"));
***********************************************************************************************************/
}
}
}
/**
* This is where we can add markers or lines, add listeners or move the camera. In this case, we
* just add a marker near Africa.
* <p>
* This should only be called once and when we are sure that {@link #mMap} is not null.
*/
private void setUpMap() {
mMap.addMarker(changeMarker());
CameraPosition cameraPosition = new CameraPosition.Builder()
.target(latLngOfMyLocation)
.zoom(22)
.bearing(-14)
.tilt(70)
.build();
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
}
public Location getMyLocation(){
// Global variable to hold the current location
Location mCurrentLocation;
mCurrentLocation = mLocationClient.getLastLocation();
return mCurrentLocation;
}
public MarkerOptions changeMarker(){
// create marker
MarkerOptions marker = new MarkerOptions().position(latLngOfMyLocation).title("ME");
// Changing marker icon
marker.icon(BitmapDescriptorFactory.fromResource(R.drawable.my_marker_icon));
return marker;
}
}