我需要使用不在Activity中的单独类来获取当前位置。这是我的代码，它不起作用。任何人都有想法解决这个问题。当我尝试获取位置详细信息时，此应用程序总是崩溃。
package com.example.ishanfx.departmentapp.network;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
public class LocationHandler implements LocationListener,GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {
private LocationManager locationManager;
Location mLastLocation;
LocationRequest mLocationRequest;
private String latitude;
private String longitude;
Context context;
private static GoogleApiClient mGoogleApiClient;
public LocationHandler(Context context) {
this.context = context;
locationManager = (LocationManager) context
.getSystemService(Context.LOCATION_SERVICE);
buildGoogleApiClient();
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(context)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
private void setMostRecentLocation(Location lastKnownLocation) {
}
public String getLatitude() {
return latitude;
}
public String getLongitude() {
return longitude;
}
@Override
public void onLocationChanged(Location location) {
double lon = (double) (location.getLongitude());
double lat = (double) (location.getLatitude());
latitude = lat + "";
longitude = lon + "";
}
/*
* (non-Javadoc)
*
* @see
* android.location.LocationListener#onProviderDisabled(java.lang.String)
*/
@Override
public void onProviderDisabled(String arg0) {
// TODO Auto-generated method stub
}
/*
* (non-Javadoc)
*
* @see
* android.location.LocationListener#onProviderEnabled(java.lang.String)
*/
@Override
public void onProviderEnabled(String arg0) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
// TODO Auto-generated method stub
}
@Override
public void onConnected(Bundle bundle) {
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
mGoogleApiClient);
if (mLastLocation != null) {
latitude =String.valueOf(mLastLocation.getLatitude());
longitude = String.valueOf(mLastLocation.getLongitude());
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
}
这是mainActivity。当我调用此应用程序时会崩溃。
LocationHandler appLocationManager = new LocationHandler(HomeActivity.this);
Toast.makeText(getApplicationContext(), appLocationManager.getLatitude().toString(), Toast.LENGTH_SHORT).show();
Toast.makeText(getApplicationContext(), appLocationManager.getLongitude().toString(), Toast.LENGTH_SHORT).show();
这是日志
FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.ishanfx.departmentapp.HomeActivity.onOptionsItemSelected(HomeActivity.java:172)
at android.app.Activity.onMenuItemSelected(Activity.java:2502)
at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:361)
at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:147)
at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:100)
at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:100)
at android.support.v7.app.ToolbarActionBar$2.onMenuItemClick(ToolbarActionBar.java:68)
at android.support.v7.widget.Toolbar$1.onMenuItemClick(Toolbar.java:172)
at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:760)
at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:811)
at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152)
at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:958)
at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:948)
at android.support.v7.view.menu.MenuPopupHelper.onItemClick(MenuPopupHelper.java:191)
at android.widget.AdapterView.performItemClick(AdapterView.java:292)
at android.widget.AbsListView.performItemClick(AbsListView.java:1065)
at android.widget.AbsListView$PerformClick.run(AbsListView.java:2522)
at android.widget.AbsListView$1.run(AbsListView.java:3183)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4441)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：2)
我已经以干净的方式更新了上面的课程。
public class LocationHandler implements LocationListener,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener {
private Context mContext;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
private OnLocationUpdateListener onLocationUpdateListener;
public LocationHandler(Context mContext) {
this.mContext = mContext;
buildGoogleApiClient();
createLocationRequest();
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(mContext)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
public void startLocationUpdates(Context mContext) {
if (ActivityCompat.checkSelfPermission(mContext,
Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
&& ActivityCompat.checkSelfPermission(mContext,
Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);
}
private void stopLocationUpdate(Context mContext) {
LocationServices.FusedLocationApi.removeLocationUpdates(
mGoogleApiClient, this);
}
//other new Methods but not using right now..
protected void createLocationRequest() {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10000);//set the interval in which you want to get locations
mLocationRequest.setFastestInterval(5000);//if a location is available sooner you can get it (i.e. another app is using the location services)
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
@Override
public void onConnected(@Nullable Bundle bundle) {
startLocationUpdates(mContext);
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
@Override
public void onLocationChanged(Location location) {
if(mGoogleApiClient.isConnected() && onLocationUpdateListener != null){
onLocationUpdateListener.onLocationChange(location);
}
}
public void setOnLocationUpdateListener(OnLocationUpdateListener onLocationUpdateListener) {
this.onLocationUpdateListener = onLocationUpdateListener;
}
}
其中 OnLocationUpdateListener 是
public interface OnLocationUpdateListener {
void onLocationChange(Location location);
void onError(EnumUtil.ErrorType errorType);
}
答案 1 :(得分：1)
onConnected事件需要一点时间才能触发。 在制作祝酒词之前，你需要给它一点时间。 我将isConnected属性添加到您的LocationHandler类，如下所示：
private boolean isconnected = false;
public boolean isConnected() {
return isconnected;
}
@Override
public void onConnected(Bundle bundle) {
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
mGoogleApiClient);
if (mLastLocation != null) {
latitude =String.valueOf(mLastLocation.getLatitude());
longitude = String.valueOf(mLastLocation.getLongitude());
}
this.isconnected = true;
}
然后在MainActivity中
LocationHandler appLocationManager = new LocationHandler(HomeActivity.this);
while(!appLocationManager.isConnected()) {
// wait for a bit
}
if (appLocationManager.isConnected()) {
Toast.makeText(getApplicationContext(), appLocationManager.getLatitude().toString(), Toast.LENGTH_SHORT).show();
Toast.makeText(getApplicationContext(), appLocationManager.getLongitude().toString(), Toast.LENGTH_SHORT).show();
}
答案 2 :(得分：0)
您必须先使用setter设置纬度和经度，然后再使用getter进行获取。由于未设置任何值，getter返回的是null值，因此null指针异常。
答案 3 :(得分：0)
这里是FusedLocationProviderClient已弃用的另一种解决方案。
FusedLocationApi其中OnLocationUpdateListener是
public class LocationHandler {
private Activity activity;
private FusedLocationProviderClient mFusedLocationProviderClient;
private Location mLastKnownLocation;
private LocationCallback mLocationCallback;
private LocationRequest mLocationRequest;
private OnLocationUpdateListener onLocationUpdateListener;
private boolean updateStartedInternally = false;
public LocationHandler(Activity activity, OnLocationUpdateListener onLocationUpdateListener) {
this.activity = activity;
this.onLocationUpdateListener = onLocationUpdateListener;
mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(activity);
createLocationRequest();
getDeviceLocation();
mLocationCallback = new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
List<Location> locationList = locationResult.getLocations();
if (locationList.size() > 0) {
//The last location in the list is the newest
Location location = locationList.get(locationList.size() - 1);
mLastKnownLocation = location;
if (onLocationUpdateListener != null) {
onLocationUpdateListener.onLocationChange(location);
if(updateStartedInternally){
stopLocationUpdate();
}
}
}
}
};
}
private void getDeviceLocation() {
/*
* Get the best and most recent location of the device, which may be null in rare
* cases when a location is not available.
*/
try {
Task locationResult = mFusedLocationProviderClient.getLastLocation();
locationResult.addOnCompleteListener(activity, task -> {
if (task.isSuccessful()) {
// Set the map's camera position to the current location of the device.
mLastKnownLocation = (Location) task.getResult();
if (mLastKnownLocation == null) {
updateStartedInternally = true;
mFusedLocationProviderClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.myLooper());
} else {
onLocationUpdateListener.onLocationChange(mLastKnownLocation);
}
} else {
onLocationUpdateListener.onError("Can't get Location");
}
});
} catch (SecurityException e) {
Log.e("Exception: %s", e.getMessage());
onLocationUpdateListener.onError(e.getMessage());
}
}
public void startLocationUpdates() {
if (ActivityCompat.checkSelfPermission(activity, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(activity, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
updateStartedInternally = false;
mFusedLocationProviderClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.myLooper());
}
private void stopLocationUpdate() {
mFusedLocationProviderClient.removeLocationUpdates(mLocationCallback);
}
//other new Methods but not using right now..
protected void createLocationRequest() {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10000);//set the interval in which you want to get locations
mLocationRequest.setFastestInterval(5000);//if a location is available sooner you can get it (i.e. another app is using the location services)
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
}