这是我的android项目。该应用程序显示有关当前位置的信息。
但是，该应用程序始终显示该位置为空。我已经搜索了很多，但是仍然找不到解决方案或无法实施该解决方案。
这是我的MainActivity代码，
package com.learning.pranavjain.hikerswatch;
import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.WindowManager;
import android.widget.TextView;
import java.io.IOException;
import java.util.List;
import java.util.Locale;
public class MainActivity extends Activity implements LocationListener {
LocationManager locationManager;
String provider;
String sLatitude;
String sLongitude;
String sAccuracy;
String sSpeed;
String sAltitude;
TextView addressTV;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Hiding the status bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
provider = locationManager.getBestProvider(new Criteria(),false);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
locationManager.requestLocationUpdates(provider,400,1,this);
location = locationManager.getLastKnownLocation(provider);
if(location==null){
Log.i("Location1","NULL1");
Toast.makeText(this,"Location not found",Toast.LENGTH_SHORT).show();
}
if(location!=null) {
onLocationChanged(location);
Log.i("Location1","Reached here");
}
}
@Override
protected void onResume() {
super.onResume();
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
locationManager.requestLocationUpdates(provider, 400, 1, this);
}
@Override
public void onLocationChanged(Location location) {
Double lat = location.getLatitude();
Double lng = location.getLongitude();
Float acc = location.getAccuracy();
Float spe = location.getSpeed();
Double alt = location.getAltitude();
Log.i("Location","reached here");
TextView latitude = (TextView) findViewById(R.id.latitude);
TextView longitude = (TextView) findViewById(R.id.longitude);
TextView accuracy = (TextView) findViewById(R.id.accuracy);
TextView speed = (TextView) findViewById(R.id.speed);
TextView altitude = (TextView) findViewById(R.id.altitude);
addressTV = (TextView) findViewById(R.id.address);
sLatitude = latitude.getText().toString();
sLongitude = longitude.getText().toString();
sAccuracy = accuracy.getText().toString();
sSpeed = speed.getText().toString();
sAltitude = altitude.getText().toString();
sLatitude += Double.toString(lat);
sLongitude += Double.toString(lng);
sAccuracy += Double.toString(acc);
sSpeed += Double.toString(spe);
sAltitude += Double.toString(alt);
latitude.setText(sLatitude);
longitude.setText(sLongitude);
accuracy.setText(sAccuracy);
speed.setText(sSpeed);
altitude.setText(sAltitude);
Geocoder geocoder = new Geocoder(getApplicationContext(), Locale.getDefault());
try {
List<Address> listAddresses = geocoder.getFromLocation(lat, lng, 1);
if (listAddresses != null && listAddresses.size() > 0 ) {
Log.i("PlaceInfo", listAddresses.get(0).toString());
String addressHolder = "";
for (int i = 0; i <= listAddresses.get(0).getMaxAddressLineIndex(); i++) {
addressHolder += listAddresses.get(0).getAddressLine(i) + "\n";
}
addressTV.setText("Address:\n" + addressHolder);
}
} catch (IOException e) {
e.printStackTrace();
}
Log.i("Location:", String.valueOf(lat));
Log.i("Location:", lng.toString());
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
protected void onPause() {
super.onPause();
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
locationManager.removeUpdates(this);
}
}
这是我的清单代码，
<?xml version="1.0" encoding="utf-8"?>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-feature android:name="android.hardware.location.network" />
<uses-feature android:name="android.hardware.location.gps" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
嗨，为什么要尝试使用getLastKnownLocation。它会返回您以前的经度和纬度，并且可能需要一些时间来更新lastknown location。很有可能它会在您所在的位置后重新运行以使您返回null。
我只是在指您google Fused api来定位任何更新或最新的位置。它非常准确。
如何在您的项目中融合api。
步骤1.使此类成为GoogleLocationService.java
public class GoogleLocationService {
private GoogleServicesCallbacks callbacks = new GoogleServicesCallbacks();
LocationUpdateListener locationUpdateListener;
Context activity;
protected GoogleApiClient mGoogleApiClient;
protected LocationRequest mLocationRequest;
public static final long UPDATE_INTERVAL_IN_MILLISECONDS = 30000;
public GoogleLocationService(Context activity, LocationUpdateListener locationUpdateListener) {
this.locationUpdateListener = locationUpdateListener;
this.activity = activity;
buildGoogleApiClient();
}
protected synchronized void buildGoogleApiClient() {
//Log.i(TAG, "Building GoogleApiClient");
mGoogleApiClient = new GoogleApiClient.Builder(activity)
.addConnectionCallbacks(callbacks)
.addOnConnectionFailedListener(callbacks)
.addApi(LocationServices.API)
.build();
createLocationRequest();
mGoogleApiClient.connect();
}
protected void createLocationRequest() {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}
private class GoogleServicesCallbacks implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener {
@Override
public void onConnected(Bundle bundle) {
startLocationUpdates();
}
@Override
public void onConnectionSuspended(int i) {
mGoogleApiClient.connect();
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
if (connectionResult.getErrorCode() == ConnectionResult.SERVICE_VERSION_UPDATE_REQUIRED) {
Toast.makeText(activity, "Google play service not updated", Toast.LENGTH_LONG).show();
}
locationUpdateListener.cannotReceiveLocationUpdates();
}
@Override
public void onLocationChanged(Location location) {
if (location.hasAccuracy()) {
if (location.getAccuracy() < 30) {
locationUpdateListener.updateLocation(location);
}
}
}
}
private static boolean locationEnabled(Context context) {
boolean gps_enabled = false;
LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
try {
gps_enabled = lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
} catch (Exception ex) {
ex.printStackTrace();
}
return gps_enabled;
}
private boolean servicesConnected(Context context) {
return isPackageInstalled(GooglePlayServicesUtil.GOOGLE_PLAY_STORE_PACKAGE, context);
}
private boolean isPackageInstalled(String packagename, Context context) {
PackageManager pm = context.getPackageManager();
try {
pm.getPackageInfo(packagename, PackageManager.GET_ACTIVITIES);
return true;
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
return false;
}
}
public void startUpdates() {
/*
* Connect the client. Don't re-start any requests here; instead, wait
* for onResume()
*/
if (servicesConnected(activity)) {
if (locationEnabled(activity)) {
locationUpdateListener.canReceiveLocationUpdates();
startLocationUpdates();
} else {
locationUpdateListener.cannotReceiveLocationUpdates();
Toast.makeText(activity, "Unable to get your location.Please turn on your device Gps", Toast.LENGTH_LONG).show();
}
} else {
locationUpdateListener.cannotReceiveLocationUpdates();
Toast.makeText(activity, "Google play service not available", Toast.LENGTH_LONG).show();
}
}
//stop location updates
public void stopUpdates() {
stopLocationUpdates();
}
//start location updates
private void startLocationUpdates() {
if (checkSelfPermission(activity, ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(activity, ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
if (mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, callbacks);
}
}
public void stopLocationUpdates() {
if (mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, callbacks);
}
}
public void startGoogleApi() {
mGoogleApiClient.connect();
}
public void closeGoogleApi() {
mGoogleApiClient.disconnect();
}
}
第2步。将此接口设置为LocationUpdateListener.java
public interface LocationUpdateListener {
/**
* Called immediately the service starts if the service can obtain location
*/
void canReceiveLocationUpdates();
/**
* Called immediately the service tries to start if it cannot obtain location - eg the user has disabled wireless and
*/
void cannotReceiveLocationUpdates();
/**
* Called whenever the location has changed (at least non-trivially)
* @param location
*/
void updateLocation(Location location);
/**
* Called when GoogleLocationServices detects that the device has moved to a new location.
* @param localityName The name of the locality (somewhere below street but above area).
*/
void updateLocationName(String localityName, Location location);
}
第3步。在您要获取位置的位置使用这段代码
public class MainActivity extends ActionBarActivity {
private GoogleLocationService googleLocationService;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
googleLocationService = new GoogleLocationService(context, new LocationUpdateListener() {
@Override
public void canReceiveLocationUpdates() {
}
@Override
public void cannotReceiveLocationUpdates() {
}
//update location to our servers for tracking purpose
@Override
public void updateLocation(Location location) {
if (location != null ) {
Timber.e("updated location %1$s %2$s", location.getLatitude(), location.getLongitude());
}
}
@Override
public void updateLocationName(String localityName, Location location) {
googleLocationService.stopLocationUpdates();
}
});
googleLocationService.startUpdates();
}
@Override
public void onDestroy() {
super.onDestroy();
if (googleLocationService != null) {
googleLocationService.stopLocationUpdates();
}
}
}
希望这会帮助你。
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