用户在谷歌地图上的位置

Question

我编写了一个使用谷歌地图API的简单程序，该程序首先关注用户的位置。 应用程序正常运行，但在函数

中

mMap.animateCamera (CameraUpdateFactory.newLatLngZoom (getMyLocation (), 22)); 

我将缩放值设置得太大（例如22），网络摄像头地图突出显示距离用户位置大约两个街区的点。 如果你能找到解决方案，我会很高兴的。 以下是我的计划：

package ebookfrenzy.com.mapdemo;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.provider.Settings;
import android.support.v4.app.FragmentActivity;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.UiSettings;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapDemoActivity extends FragmentActivity {

    private GoogleMap mMap; // Might be null if Google Play services APK is not available.


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map_demo);
        //the message of the location service
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("Make sure your location services are turned on, whether not do you want turn them on?").setPositiveButton("Yes", dialogClickListener)
                .setNegativeButton("No", dialogClickListener).show();
        setUpMapIfNeeded();

    }

    //Setting pop-up window and is derivatives
    DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            switch (which){
                case DialogInterface.BUTTON_POSITIVE:
                    //Yes button clicked
                    Intent intent=new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                    startActivity(intent);
                    break;

                case DialogInterface.BUTTON_NEGATIVE:
                    //No button clicked
                    break;
            }
        }
    };

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }

    /**
     * Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
     * installed) and the map has not already been instantiated.. This will ensure that we only ever
     * call {@link #setUpMap()} once when {@link #mMap} is not null.
     * <p>
     * If it isn't installed {@link SupportMapFragment} (and
     * {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
     * install/update the Google Play services APK on their device.
     * <p>
     * A user can return to this FragmentActivity after following the prompt and correctly
     * installing/updating/enabling the Google Play services. Since the FragmentActivity may not
     * have been completely destroyed during this process (it is likely that it would only be
     * stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
     * method in {@link #onResume()} to guarantee that it will be called.
     */
    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();
            // Check if we were successful in obtaining the map.
            if (mMap != null) {
                setUpMap();
                    //Setting up the map settings
                    UiSettings mapSettings;
                    mapSettings = mMap.getUiSettings();
                    //Approval to the application to use location services
                    mMap.setMyLocationEnabled(true);
                    //lock all options built-in buttons in google maps without locking their abilities
                    mapSettings.setMyLocationButtonEnabled(false);
                    mapSettings.setZoomControlsEnabled(false);
                    mapSettings.setCompassEnabled(false);
                    /***********************************************************************************************************
                     LatLng MUSEUM = new LatLng(38.8874245, -77.0200729);
                     Marker museum = mMap.addMarker(new MarkerOptions().position(MUSEUM).title("Museum").snippet("National Air and Space Museum"));
                     ***********************************************************************************************************/
            }
        }
    }

    /**
     * This is where we can add markers or lines, add listeners or move the camera. In this case, we
     * just add a marker near Africa.
     * <p>
     * This should only be called once and when we are sure that {@link #mMap} is not null.
     */
    private void setUpMap() {
        mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(getMyLocation(), 22));
    }

   public LatLng getMyLocation()
    {
        //get locationManager object from System Service LOCATION_SERVICE
        LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

        Criteria criteria = new Criteria();

        String provider = locationManager.getBestProvider(criteria, true);

        Location myLocation = locationManager.getLastKnownLocation(provider);

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

        LatLng latLng = new LatLng(latitude, longitude);
        return latLng;
    }
}