我正在编写一个简单的应用程序，需要从假设 A 点设置当前 GPS 坐标，然后前往另一个 B 点并让它检测 B 点的坐标。我能够获得 A 点坐标没有问题。我只是没有让它检测 B 点的坐标，它读取的坐标与 A 点的坐标相同。我的手机上安装了应用程序，我在两点之间行驶了一英里。我的清单文件包含所有可能的位置许可。
这是活动代码。
public class GPSTrackingActivity extends Activity {
Button btnShowLocation;
Button btnShowEndLocation;
// GPSTracker class
GPSTracker gps;
TextView tvIntialLocation;
TextView tvEndLocation;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myDBHelper = new DataBaseHelper(GPSTrackingActivity.this);
tvIntialLocation = (TextView)findViewById(R.id.tvIntialLocation);
tvEndLocation = (TextView)findViewById(R.id.tvEndLocation);
// create class object
gps = new GPSTracker(GPSTrackingActivity.this);
btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
btnShowEndLocation = (Button)findViewById(R.id.btnEndLocation);
// show location button click event
btnShowLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// check if GPS enabled
if(gps.canGetLocation()){
double latitude = gps.getLatitude();
double longitude = gps.getLongitude();
tvIntialLocation.setText("Start Location is - \nLat: " + latitude + "\nLong: " + longitude);
}else{
// can't get location
// GPS or Network is not enabled
// Ask user to enable GPS/network in settings
gps.showSettingsAlert();
}
}
});
// show location button click event
btnShowEndLocation.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// check if GPS enabled
if(gps.canGetLocation()){
double latitude = gps.getLatitude();
double longitude = gps.getLongitude();
tvEndLocation.setText("End Location is - \nLat: " + latitude + "\nLong: " + longitude);
}else{
// can't get location
// GPS or Network is not enabled
// Ask user to enable GPS/network in settings
gps.showSettingsAlert();
}
}
});
}
}
这是设置 GPS Tracker 类的类。我不确定是否调用了 onLocationChanged，当我开车时位置发生变化时，我没有看到任何 Toast 消息。
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;
// First get location from Network Provider
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;
}
/**
* 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;
}
@Override
public void onLocationChanged(Location location) {
location = getLocation();
// Testing onLocationChanged:
String hej1 = Double.toString(location.getLatitude());
String hej2 = Double.toString(location.getLongitude());
Toast.makeText(this, "Location: "+"Lat: " + hej1 + "Long: " + hej2,
Toast.LENGTH_LONG).show();
}
/**
* 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();
}
}
为什么第二个点没有更新到当前位置？起点和终点显示为相同的 GPS 坐标。