我正在创建一个应用程序来查找用户的当前位置。 我提到了这个链接 What is the simplest and most robust way to get the user's current location on Android?
创建我的应用。 我的问题我已尝试与两个提供程序，但它没有检测到任何提供程序，结果总是location = null返回。 为什么会出现这个问题以及如何在手机中获取该位置。 提前谢谢......
我的代码就在这里 这是MyLocation.java类
package com.example.locationupadates;
import java.util.Timer;
import java.util.TimerTask;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
public class MyLocation {
Timer timer1;
LocationManager lm;
LocationResult locationResult;
boolean gps_enabled=false;
boolean network_enabled=false;
public boolean getLocation(Context context, LocationResult result)
{
//I use LocationResult callback class to pass location value from MyLocation to user code.
locationResult=result;
if(lm==null)
lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
//exceptions will be thrown if provider is not permitted.
try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
Log.v("Ansar",""+"Network Enabled");}catch(Exception ex){}
try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
Log.v("Ansar",""+"Network Enabled");}catch(Exception ex){}
//don't start listeners if no provider is enabled
if(!gps_enabled && !network_enabled){
Log.v("Ansar",""+"Not anything Enabled");
return false;
}
if(gps_enabled){
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
Log.v("Ansar",""+"Location Listener Gps");
} if(network_enabled){
lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
Log.v("Ansar",""+"Location Listener Network");
} timer1=new Timer();
timer1.schedule(new GetLastLocation(), 20000);
return true;
}
LocationListener locationListenerGps = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
locationResult.gotLocation(location);
lm.removeUpdates(this);
lm.removeUpdates(locationListenerNetwork);
Log.v("Ansar",""+location.getLongitude());
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
LocationListener locationListenerNetwork = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
locationResult.gotLocation(location);
lm.removeUpdates(this);
lm.removeUpdates(locationListenerGps);
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
class GetLastLocation extends TimerTask {
@Override
public void run() {
lm.removeUpdates(locationListenerGps);
lm.removeUpdates(locationListenerNetwork);
Location net_loc=null, gps_loc=null;
if(gps_enabled)
gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(network_enabled)
net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//if there are both values use the latest one
if(gps_loc!=null && net_loc!=null){
if(gps_loc.getTime()>net_loc.getTime())
locationResult.gotLocation(gps_loc);
else
locationResult.gotLocation(net_loc);
return;
}
if(gps_loc!=null){
locationResult.gotLocation(gps_loc);
return;
}
if(net_loc!=null){
locationResult.gotLocation(net_loc);
return;
}
locationResult.gotLocation(null);
}
}
public static abstract class LocationResult{
public abstract void gotLocation(Location location);
}
}
MainActivity.java
package com.example.locationupadates;
import android.app.Activity;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;
import com.example.locationupadates.MyLocation.LocationResult;
public class MainActivity extends Activity {
TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView) findViewById(R.id.tv);
Log.d("Ansar",""+"oncreate");
LocationResult locationResult = new LocationResult(){
@Override
public void gotLocation(Location location){
Log.v("Ansar",""+location.getLongitude());
tv.setText("location:"+location+"latitude: "+location.getLatitude()+"longitude "+location.getLongitude());
}
};
MyLocation myLocation = new MyLocation();
myLocation.getLocation(this, locationResult);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
的Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.locationupadates"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="10"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.locationupadates.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
例外
02-21 11:39:05.963: W/dalvikvm(18909): threadid=11: thread exiting with uncaught exception (group=0x410e4390)
02-21 11:39:05.963: E/AndroidRuntime(18909): FATAL EXCEPTION: Timer-0
02-21 11:39:05.963: E/AndroidRuntime(18909): java.lang.NullPointerException
02-21 11:39:05.963: E/AndroidRuntime(18909): at com.example.locationupadates.MainActivity$1.gotLocation(MainActivity.java:23)
02-21 11:39:05.963: E/AndroidRuntime(18909): at com.example.locationupadates.MyLocation$GetLastLocation.run(MyLocation.java:102)
02-21 11:39:05.963: E/AndroidRuntime(18909): at java.util.Timer$TimerImpl.run(Timer.java:284)
02-21 11:39:05.963: W/dalvikvm(18909): threadid=11: thread exiting with uncaught exception (group=0x410e4390)
02-21 11:39:05.963: E/AndroidRuntime(18909): FATAL EXCEPTION: Timer-0
02-21 11:39:05.963: E/AndroidRuntime(18909): java.lang.NullPointerException
02-21 11:39:05.963: E/AndroidRuntime(18909): at com.example.locationupadates.MainActivity$1.gotLocation(MainActivity.java:23)
02-21 11:39:05.963: E/AndroidRuntime(18909): at com.example.locationupadates.MyLocation$GetLastLocation.run(MyLocation.java:102)
02-21 11:39:05.963: E/AndroidRuntime(18909): at java.util.Timer$TimerImpl.run(Timer.java:284)
答案 0 :(得分：0)
尝试下面的课......我想帮助你......
添加主要活动......
GPSTracker gps =新的GPSTracker（ActivityNearBy.this）;
if (gps.canGetLocation()) {
latitude = gps.getLatitude();
longitude = gps.getLongitude();
}
GPS服务
public class GPSTracker extends Service implements LocationListener {
private final Context mContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
// Declaring a Location Manager
protected LocationManager locationManager;
public GPSTracker(Context context) {
this.mContext = context;
getLocation();
}
public Location getLocation() {
try {
locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled) {
// no network provider is enabled
} else {
this.canGetLocation = true;
if (isNetworkEnabled) {
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled) {
if (location == null) {
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
/**
* Stop using GPS listener Calling this function will stop using GPS in your
* app
* */
public void stopUsingGPS() {
if (locationManager != null) {
locationManager.removeUpdates(GPSTracker.this);
}
}
/**
* Function to get latitude
* */
public double getLatitude() {
if (location != null) {
latitude = location.getLatitude();
}
// return latitude
return latitude;
}
/**
* Function to get longitude
* */
public double getLongitude() {
if (location != null) {
longitude = location.getLongitude();
}
// return longitude
return longitude;
}
/**
* Function to check GPS/wifi enabled
*
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog On pressing Settings button will
* lauch Settings Options
* */
public void showSettingsAlert() {
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
}
});
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
// Showing Alert Message
alertDialog.show();
}
@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
}
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onRebind(Intent intent) {
// TODO Auto-generated method stub
super.onRebind(intent);
}
@Override
public boolean onUnbind(Intent intent) {
// TODO Auto-generated method stub
return super.onUnbind(intent);
}
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}}
更新 manifest.xml
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />