使用GPS获取当前位置,无需网络

时间:2013-09-20 10:13:07

标签: android location android-maps-v2

我需要使用GPS获取myLocation,如何获得它?我尝试下一个代码,但它永远不会工作。当我重新启动手机并运行应用程序时,它无效。

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 GPSTraker 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 = 1; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 3000; // 1 minute

// Declaring a Location Manager
protected LocationManager locationManager;

public GPSTraker(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(GPSTraker.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 void onLocationChanged(Location location) {
}

@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;

}
 }

并使用它:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    v = inflater.inflate(R.layout.fragment_near_new, null);
    elvMain = (ExpandableListView) v.findViewById(R.id.elvMain);
    GPSTraker gps = new GPSTraker(getActivity());

    if (gps.canGetLocation()) {
        myLat = gps.getLatitude();
        myLong = gps.getLongitude();
        Log.d("myDebug", "new get Location +" + myLat);
        // \n is for new line

    } else {
        // can't get location
        // GPS or Network is not enabled
        // Ask user to enable GPS/network in settings
        Log.d("myDebug", "Can not get location");
        gps.showSettingsAlert();
    }


    return v;
}

这是错的?也许有人有一些想法如何解决这个问题?重新启动手机后this program  也不能得到我的位置。

1 个答案:

答案 0 :(得分:1)

您想要连续的位置更新还是只需要一个位置?

通过“GPS,无网络”我假设您想要获得一个位置,即使网络不可用,也不应该永远不要使用网络位置。

LocationManager上的一些基础知识:

启动时,您需要请求LocationManager的实例,然后调用RequestLocationUpdates(),并将接收位置更新的类作为参数传递。当新位置可用时,LocationManager将调用onLocationChanged(),并将当前位置作为参数传递。

查看你的代码,你可以在那里找到它,但是在错误的地方:

  • getLocation()方法中的大多数代码都应该进入onCreate()
  • requestLocationUpdates()的调用应该采用您服务的onStartCommand()方法。您应该通过removeUpdates()方法中的stopSelf()取消注册,以便在您的服务停止时释放GPS。 (对于活动,分别在onResume()onPause()中执行此操作。否则,即使服务停止/用户离开活动,它也会保持GPS唤醒并耗尽电量,直到系统终止应用程序。)
  • 您在onCreateView()中处理位置更新的代码应该进入onLocationChanged()

我看到你也在呼叫LocationManager.getLastKnownLocation()。这将获得LocationManager之前获得的最后位置,但不会启动GPS。如果之前没有其他应用请求过位置更新(使用requestLocationUpdates()),则无法报告位置,如果设备自上次获得位置后移动,您将获得过期位置。< / p>

如果您需要以可靠的方式更新单个位置信息并获取最新信息,请按照上述说明操作,并在removeUpdates()方法中拨打onLocationChanged()。这将在第一次位置更新后释放GPS。请注意,您可能需要等待一段时间才能进行位置更新,因为GPS可能需要一些时间才能启动。