android - 确定位置 gps 和 wifi

Question

我想在确定设备位置时显示一个对话框。我还想同时使用 wifi 和 gps 提供商。当位置发生变化时，应更新纬度和经度值。我找了一个例子，但我没有找到任何东西。

Answer 1

这是一个如何定义位置管理器并获取位置更改事件的示例：

public class LocationChangeListener  implements LocationListener{


private LocationManager mLocationManager = null;
private static final int TWO_MINUTES = 1000 * 60 * 2;
private Location currentBestLocation = null;

public LocationChangeListener(Context context) {
    super(context);
}

public void impl(int refreshPeriod, int accuracyInMeters){



    // Get the location manager
    mLocationManager = (LocationManager) ctx.getSystemService(Context.LOCATION_SERVICE);

    currentBestLocation = getLastBestLocation();

    boolean enabled = mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

    // Check if enabled and if not send user to the GSP settings
    // Better solution would be to display a dialog and suggesting to 
    // go to the settings
    if (!enabled) {
        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
        mContext.startActivity(intent);
    } 


    Criteria criteria = new Criteria();
    //criteria.setAccuracy(Criteria.ACCURACY_FINE);
    //criteria.setCostAllowed(false);

    String provider = mLocationManager.getBestProvider(criteria, false);
    Location location = mLocationManager.getLastKnownLocation(provider);

    LocationListener listener = this;       
    mLocationManager.requestLocationUpdates(provider, refreshPeriod, accuracyInMeters, listener);
    //mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, listener);
    //mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, listener);

    this.onLocationChanged(location);

    // Initialize the location fields
    if (location == null) {
        //Location not available

        mLocationManager.removeUpdates(this);
    }

}

/**
 * This method returns the last know location, between the GPS and the Network one.
 * For this method newer is best :)
 * 
 * @return the last know best location
 */
private Location getLastBestLocation() {
    Location locationGPS = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    Location locationNet = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

    long GPSLocationTime = 0;
    if (null != locationGPS) { GPSLocationTime = locationGPS.getTime(); }

    long NetLocationTime = 0;

    if (null != locationNet) {
        NetLocationTime = locationNet.getTime();
    }

    if ( 0 < GPSLocationTime - NetLocationTime ) {
        return locationGPS;
    }
    else{
        return locationNet;
    }

}

/**
 * This method modify the last know good location according to the arguments.
 * 
 * @param location      the possible new location
 */
void makeUseOfNewLocation(Location location) {
    if ( isBetterLocation(location, currentBestLocation) ) {
        currentBestLocation = location;
    }
}

public void onLocationChanged(Location location) {

    makeUseOfNewLocation(location);

    if(currentBestLocation == null){
        currentBestLocation = location;
    }


    FlowController.isTriggerEventReceived = true;       
    mCobytLocationCallback.onLocationChanged(currentBestLocation);      
}

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

}

public void onProviderEnabled(String provider) {


}

public void onProviderDisabled(String provider) {


}   

/** Determines whether one Location reading is better than the current Location fix
 * @param location  The new Location that you want to evaluate
 * @param currentBestLocation  The current Location fix, to which you want to compare the new one
 */
protected boolean isBetterLocation(Location location, Location currentBestLocation) {
    if (currentBestLocation == null) {
        // A new location is always better than no location
        return true;
    }

    // Check whether the new location fix is newer or older
    long timeDelta = location.getTime() - currentBestLocation.getTime();
    boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
    boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
    boolean isNewer = timeDelta > 0;

    // If it's been more than two minutes since the current location, use the new location
    // because the user has likely moved
    if (isSignificantlyNewer) {
        return true;
        // If the new location is more than two minutes older, it must be worse
    } else if (isSignificantlyOlder) {
        return false;
    }

    // Check whether the new location fix is more or less accurate
    int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
    boolean isLessAccurate = accuracyDelta > 0;
    boolean isMoreAccurate = accuracyDelta < 0;
    boolean isSignificantlyLessAccurate = accuracyDelta > 200;

    // Check if the old and new location are from the same provider
    boolean isFromSameProvider = isSameProvider(location.getProvider(),
            currentBestLocation.getProvider());

    // Determine location quality using a combination of timeliness and accuracy
    if (isMoreAccurate) {
        return true;
    } else if (isNewer && !isLessAccurate) {
        return true;
    } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
        return true;
    }
    return false;
}

/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
    if (provider1 == null) {
        return provider2 == null;
    }
    return provider1.equals(provider2);
}



public void destroyManager() {

    if(mLocationManager != null){
        mLocationManager.removeUpdates(this);

        mLocationManager = null;
    }       
}
}

由于安卓有

GPS_PROVIDER您可以同时注册两者并从 2NETWORK_PROVIDER 开始获取事件。onLocationChanged(Location location)到现在为止还挺好。现在的问题是我们需要 2 个结果还是我们应该采取最好的。据我所知NETWORK PROVIDER，结果比GPS.

在我们开始监听位置变化之前，我们将实现跟随方法private Location getLastBestLocation()。此方法返回 GPS 和网络之间的最后一个已知位置。对于这种方法，更新的最好。