Android应用程序中的GPS位置更改

Question

我已经关注了这个tutorial 在Android 应用程序中使用这个类进行GPS 跟踪：

GPSTracker.java

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) {

    latitude = location.getLatitude();
    longitude = location.getLongitude();

}

@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;
}

这是使用前一个类的 Activity：

AndroidGPSTrackingActivity.java

package com.example.gpstracking;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class AndroidGPSTrackingActivity extends Activity {

Button btnShowLocation;

// GPSTracker class
GPSTracker gps;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    btnShowLocation = (Button) findViewById(R.id.btnShowLocation);

    // show location button click event
    btnShowLocation.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {        
            // create class object
            gps = new GPSTracker(AndroidGPSTrackingActivity.this);

            // check if GPS enabled     
            if(gps.canGetLocation()){

                double latitude = gps.getLatitude();
                double longitude = gps.getLongitude();

                // \n is for new line
                Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();    
            }else{
                // can't get location
                // GPS or Network is not enabled
                // Ask user to enable GPS/network in settings
                gps.showSettingsAlert();
            }

        }
    });
}

}

如何从 AndroidGPSTrackingActivity.java 接收新的位置更新？ 如何在 GPSTracker 类中的 onLocationChanged 获取的 AndroidGPSTrackingActivity 中获取纬度和经度？

非常感谢

Answer 1

我还不会写cmets，所以我在这里试试：

我会在您的 Activity 中创建一个 Handler 并将其分配给 GPSTracker 类：

Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
             // new GPS Informations
             // get it by gps.getLatitude() for example
        };
    };

gps = new GPSTracker(AndroidGPSTrackingActivity.this, handler);

在您的 GPSTracker 类中，您当然必须更改构造函数：

 Handler mHandler;

 public GPSTracker(Context context, Handler handler){
  ...
  this.mHandler = handler;
 }

然后，只需发送信息，即位置已更改为您的活动：

 @Override    
 public void onLocationChanged(Location location) { 
    latitude = location.getLatitude();
    longitude = location.getLongitude();
    mHandler.sendEmptyMessage(0);
 }