谷歌地图Android api v2和当前位置

Question

I'm trying to use the new google maps android api v2 and i'm developing an app for android 2.3.3 or higher. It's a very simple app: it takes the user current location (using gps or networks signal) it gets from db a POI using direction api, it drives the user to the POI.

My problem is get the user current location. thanks to this post How to get the current location in Google Maps Android API v2? I learned that i can't update current position using new google api. Another problem is that I can set my position using GoogleMap setMyLocationEnabled(boolean enabled) but I can't use getMyLocation() to know where user is.

I used this guide http://www.vogella.com/articles/AndroidLocationAPI/article.html#maps_mylocation to get my location, and i tried to integrate inside my Activity to draw user position.

here my code:

Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="it.mappe"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-permission android:name="it.mappe.permission.MAPS_RECEIVE" />

    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="16" />

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >

         <meta-data
        android:name="com.google.android.maps.v2.API_KEY"
        android:value="MYGMAPSKEY" />
        <activity
            android:name="it.mappe.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

main Activity

package it.mappe;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;

import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

import android.content.Context;
import android.content.Intent;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.provider.Settings;
import android.support.v4.app.FragmentActivity;
import android.widget.Toast;

public class MainActivity extends FragmentActivity implements LocationListener {
    private GoogleMap map;
    private static final LatLng ROMA = new LatLng(42.093230818037,11.7971813678741);
    private LocationManager locationManager;
    private String provider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

        LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE);
        boolean enabledGPS = service
                .isProviderEnabled(LocationManager.GPS_PROVIDER);
        boolean enabledWiFi = service
                .isProviderEnabled(LocationManager.NETWORK_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 (!enabledGPS) {
            Toast.makeText(this, "GPS signal not found", Toast.LENGTH_LONG).show();
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            startActivity(intent);
        }

        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        // Define the criteria how to select the locatioin provider -> use
        // default
        Criteria criteria = new Criteria();
        provider = locationManager.getBestProvider(criteria, false);
        Location location = locationManager.getLastKnownLocation(provider);

        // Initialize the location fields
        if (location != null) {
            Toast.makeText(this, "Selected Provider " + provider,
                    Toast.LENGTH_SHORT).show();
            onLocationChanged(location);
        } else {

            //do something
        }

    }

    /* Request updates at startup */
    @Override
    protected void onResume() {
        super.onResume();
        locationManager.requestLocationUpdates(provider, 400, 1, this);
    }

    /* Remove the locationlistener updates when Activity is paused */
    @Override
    protected void onPause() {
        super.onPause();
        locationManager.removeUpdates(this);
    }

    @Override
    public void onLocationChanged(Location location) {
        double lat =  location.getLatitude();
        double lng = location.getLongitude();
        Toast.makeText(this, "Location " + lat+","+lng,
                Toast.LENGTH_LONG).show();
        LatLng coordinate = new LatLng(lat, lng);
        Toast.makeText(this, "Location " + coordinate.latitude+","+coordinate.longitude,
                Toast.LENGTH_LONG).show();
        Marker startPerc = map.addMarker(new MarkerOptions()
        .position(coordinate)
        .title("Start")
        .snippet("Inizio del percorso")
        .icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)));
    }


    @Override
    public void onProviderDisabled(String provider) {
        Toast.makeText(this, "Enabled new provider " + provider,
                Toast.LENGTH_SHORT).show();

    }


    @Override
    public void onProviderEnabled(String provider) {
        Toast.makeText(this, "Disabled provider " + provider,
                Toast.LENGTH_SHORT).show();

    }


    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

}

main layout

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/map"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    class="com.google.android.gms.maps.SupportMapFragment" />

It works but not so good, as you can see in the pictures eveytime there is a new location it adds a new Marker (ex Overlay I think... I never use old google maps api).

How can I show only one markers?

In addition on my map i need to display also POI's marker, so i think that it's not a good solution delate all marker and redraw it on the maps. There is another best way to get user current location, updating it every moment displaying just one custom marker?!

Answer 1

You can call startPerc.remove(); to delete only this marker.

From here

Answer 2

为什么不使用startPerc.setPosition来移动标记而不是继续添加和删除...

Answer 3

通过此方法获取其他位置时设置标记的位置

marker. set position (location)

Answer 4

you should use googlemap.clear() before adding the marker because everytime when location changed it add new marker on map with oldest marker. so use googlemap.clear() before add the marker in location changed. it will remove oldest marker and add new marker. googlemap is the instance of GoogleMap Class.

Answer 5

You could replace the marker with a new one:

if(userMarker!=null) userMarker.remove();
    userMarker = theMap.addMarker(new MarkerOptions()
    .position(lastLatLng)
    .title("You are here")
    .icon(BitmapDescriptorFactory.fromResource(R.drawable.your_loc_icon))
    .snippet("Your current location"));

Answer 6

Full shortcut for defining the Google Map android v2 in android......

XML File :

<fragment
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />

Menifest file :

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="17" />

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<!-- Map permission Starts -->
<permission
    android:name="com.example.mapdemoapiv2.permission.MAPS_RECEIVE"
    android:protectionLevel="signature" />

<uses-permission android:name="com.example.mapdemoapiv2.permission.MAPS_RECEIVE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

<uses-feature
    android:glEsVersion="0x00020000"
    android:required="true" />

<!-- Map permission Starts -->

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.mapdemoapiv2.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".MapDetail" >
    </activity>

    <meta-data
        android:name="com.google.android.maps.v2.API_KEY"
        android:value="Your Key" />

    <uses-library android:name="com.google.android.maps" />
</application>

Activity class :

public class MainActivity extends android.support.v4.app.FragmentActivity
{
   GoogleMap googleMap;
    MarkerOptions markerOptions;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    setUpMapIfNeeded();

    GetCurrentLocation();

    }

private void setUpMapIfNeeded() {
    if (googleMap == null) {

        Log.e("", "Into null map");
        googleMap = ((SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map)).getMap();

        googleMap.setInfoWindowAdapter(new CustomInfoWindowAdapter(
                MainActivity.this));

        if (googleMap != null) {
            Log.e("", "Into full map");
            googleMap.setMapType(googleMap.MAP_TYPE_NORMAL);
            googleMap.getUiSettings().setZoomControlsEnabled(false);
        }
    }
}

private void GetCurrentLocation() {

    double[] d = getlocation();
    Share.lat = d[0];
    Share.lng = d[1];

     googleMap
            .addMarker(new MarkerOptions()
                    .position(new LatLng(Share.lat, Share.lng))
                    .title("Current Location")
                    .icon(BitmapDescriptorFactory
                            .fromResource(R.drawable.dot_blue)));

             googleMap
                .animateCamera(CameraUpdateFactory.newLatLngZoom(
                        new LatLng(Share.lat, Share.lng), 5));
}

public double[] getlocation() {
    LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    List<String> providers = lm.getProviders(true);

    Location l = null;
    for (int i = 0; i < providers.size(); i++) {
        l = lm.getLastKnownLocation(providers.get(i));
        if (l != null)
            break;
    }
    double[] gps = new double[2];

    if (l != null) {
        gps[0] = l.getLatitude();
        gps[1] = l.getLongitude();
    }
    return gps;
}

Answer 7

First of all in map api v2 use LocationClient to retreive your location, see: http://developer.android.com/training/location/retrieve-current.html

Iportant: to kick start API, call this in onStart of main Activity:

private void kickStardedLocationManager(){

 // Acquire a reference to the system Location Manager
    LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

 // Define a listener that responds to location updates
    android.location.LocationListener locationListener = new android.location.LocationListener() {
        public void onLocationChanged(Location location) {
          // Called when a new location is found by the network location provider.
            //MainActivity.this.makeUseOfNewLocation(location);
        }

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

        public void onProviderEnabled(String provider) {}

        public void onProviderDisabled(String provider) {}
      };

      long l = 10;
      float f = 100;
   // Register the listener with the Location Manager to receive location updates
      locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener); //LocationManager.GPS_PROVIDER
}