java - 在 Android 屏幕上更新位置数据

Question

我想更新 Android 屏幕上的位置数据。我在 LiczydloGPS.class 中有 LocationListener 和 LocationManager :

package com.zoltrix.gpsallinfo;

import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;

public class LiczydloGPS extends Service implements LocationListener {

    private final Context mContext;

    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    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 LiczydloGPS(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;
    }

    @Override
    public void onLocationChanged(Location location) {

        if(location!=null)
        {
        MainActivity main2 = new MainActivity();

        main2.update(location.getLatitude(), location.getLongitude());
        }
        Log.d("onLocationChanged", "idze do maina");
    }

    @Override
    public void onProviderDisabled(String provider) {
    }

    @Override
    public void onProviderEnabled(String provider) {
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
    }

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

    /**
     * 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 if best network provider
     * 
     * @return boolean
     * */
    public boolean canGetLocation() {
        return this.canGetLocation;
    }

    /**
     * Function to show settings alert dialog
     * */
    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?");

        // Setting Icon to Dialog
        // alertDialog.setIcon(R.drawable.delete);

        // 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();
    }
    /**
     * Stop using GPS listener
     * Calling this function will stop using GPS in your app
     * */
    public void stopUsingGPS(){
        if(locationManager != null){
            locationManager.removeUpdates(LiczydloGPS.this);
        }       
    }
}

在 MainActivity 中，我制作了方法 update，该方法在 onLocationChanged 的 LiczydloGPS.class 中调用:

    package com.zoltrix.gpsallinfo;

import com.zoltrix.gpsallinfo.R.id;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    double lat, lon;
    TextView latData, longData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        latData = (TextView) findViewById(R.id.latData);
        longData = (TextView) findViewById(R.id.longData);

        LiczydloGPS gps = new LiczydloGPS(this);

        if (gps.canGetLocation() != true) {
            gps.showSettingsAlert();

        } else {

            lat = gps.getLatitude(); // returns latitude
            lon = gps.getLongitude();
            latData.setText(String.valueOf(lat));
            longData.setText(String.valueOf(lon));

        }

    }

    @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;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        switch (item.getItemId()) {

        case id.oprogramie:

            Intent intent = new Intent(this, Oprogramie.class);
            startActivity(intent);
        case id.action_settings:
            Intent intent2 = new Intent(this, Ustawienia.class);
            startActivity(intent2);
        }

        return super.onOptionsItemSelected(item);
    }

    public void update(double lat1, double lon1) {
        Log.d("onLocationChanged", "jest w mainie!");
         latData.setText(lat1);
         longData.setText(lon1);

        Log.d("onLocationChanged", String.valueOf(lat1));
        //Toast.makeText(getApplicationContext(), "TOAST!!!!!!!!!!!!!!!", Toast.LENGTH_SHORT).show();

    }



}

但是当你想改变 DDMS 中的 GPS 数据时，应用程序被杀死了。日志:

11-11 09:22:27.626: D/GPS Enabled(2734): GPS Enabled 11-11 09:22:28.136: D/gralloc_goldfish(2734): Emulator without GPU emulation detected. 11-11 09:22:32.506: D/onLocationChanged(2734): jest w mainie! 11-11 09:22:32.506: D/AndroidRuntime(2734): Shutting down VM 11-11 09:22:32.506: W/dalvikvm(2734): threadid=1: thread exiting with uncaught exception (group=0xb3aa2b90) 11-11 09:22:32.516: E/AndroidRuntime(2734): FATAL EXCEPTION: main 11-11 09:22:32.516: E/AndroidRuntime(2734): Process: com.zoltrix.gpsallinfo, PID: 2734 11-11 09:22:32.516: E/AndroidRuntime(2734): java.lang.NullPointerException 11-11 09:22:32.516: E/AndroidRuntime(2734): at com.zoltrix.gpsallinfo.MainActivity.update(MainActivity.java:69) 11-11 09:22:32.516: E/AndroidRuntime(2734): at com.zoltrix.gpsallinfo.LiczydloGPS.onLocationChanged(LiczydloGPS.java:113) 11-11 09:22:32.516: E/AndroidRuntime(2734): at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:279) 11-11 09:22:32.516: E/AndroidRuntime(2734): at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:208) 11-11 09:22:32.516: E/AndroidRuntime(2734): at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:224) 11-11 09:22:32.516: E/AndroidRuntime(2734): at android.os.Handler.dispatchMessage(Handler.java:102) 11-11 09:22:32.516: E/AndroidRuntime(2734): at android.os.Looper.loop(Looper.java:137) 11-11 09:22:32.516: E/AndroidRuntime(2734): at android.app.ActivityThread.main(ActivityThread.java:4998) 11-11 09:22:32.516: E/AndroidRuntime(2734): at java.lang.reflect.Method.invokeNative(Native Method) 11-11 09:22:32.516: E/AndroidRuntime(2734): at java.lang.reflect.Method.invoke(Method.java:515) 11-11 09:22:32.516: E/AndroidRuntime(2734): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777) 11-11 09:22:32.516: E/AndroidRuntime(2734): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593) 11-11 09:22:32.516: E/AndroidRuntime(2734): at dalvik.system.NativeStart.main(Native Method)

提前感谢您的帮助

Answer 1

你需要让你的纬度和经度 insdie onLocationChanged() 像这样。

@Override
public void onLocationChanged(Location location) {
    if(location!=null)
    {
update(location.getLatitude(), location.getLongitude());
    }
}