android - 現在地を地図上に表示する

Question

私が書いたコードは、ユーザーがアプリを開いたときにデバイスの場所を地図上に表示することになっています。そのため、携帯電話で試してみたところ、開いたときに自分の場所を見ることができましたが、そこから約 2 km 歩きました。場所を選択してからアプリを再度開いたが、以前の場所が地図に表示されました。

マニフェスト:

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

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="22" />

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

    <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.gms.version"
            android:value="@integer/google_play_services_version" />
        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="my api key is here" />

        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >     
        </activity>
        <activity android:name="AlarmReceiverActivity" android:label="@string/alarmReceiverActivity_string"></activity><activity
            android:name=".MnaActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <service android:name="com.example.fgps.BackgroundLocationService" />
    </application>

</manifest>

アクティビティ：

package com.example.fgps;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentSender;
import android.location.Location;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.text.InputType;
import android.util.Log;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapLongClickListener;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends FragmentActivity implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener
//,LocationListener 
{

    public static final String TAG = MainActivity.class.getSimpleName();

    /*
     * Define a request code to send to Google Play services
     * This code is returned in Activity.onActivityResult
     */
    private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;

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

    private GoogleApiClient mGoogleApiClient;
    //private LocationRequest mLocationRequest;

    private String T_Text="";
    private double D_Text;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setUpMapIfNeeded();
        buildGoogleApiClient();
        if(mGoogleApiClient!= null){
            mGoogleApiClient.connect();
        }

        Toast.makeText(this,"Long press at the location you want to choose as your destination",Toast.LENGTH_LONG).show();
        // Create the LocationRequest object
        /*mLocationRequest = LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(6 * 1000)        // 4 seconds, in milliseconds
                .setFastestInterval(1 * 500); // 1/2 second, in milliseconds
         */

        mMap.setOnMapLongClickListener(new OnMapLongClickListener() {
            Intent i;@Override
            public void onMapLongClick(LatLng point) {
                i=new Intent(MainActivity.this, MnaActivity.class);
                i.putExtra("lat", point.latitude);
                i.putExtra("lng", point.longitude);
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setTitle("Setup");
                TextView text123 = new TextView(MainActivity.this);
                text123.setText("Enter title for alarm");
                final EditText input = new EditText(MainActivity.this);
                input.setInputType(InputType.TYPE_CLASS_TEXT);
                final EditText input2 = new EditText(MainActivity.this);
                input2.setInputType(InputType.TYPE_CLASS_TEXT);
                LinearLayout lay = new LinearLayout(MainActivity.this);
                lay.setOrientation(LinearLayout.VERTICAL);
                lay.addView(text123);
                lay.addView(input);
                TextView text12 = new TextView(MainActivity.this);
                text12.setText("Enter raduis to start alarm\n(in Kms and above 200m)");
                lay.addView(text12);
                lay.addView(input2);
                builder.setView(lay);


                builder.setPositiveButton("OK", new DialogInterface.OnClickListener() { 
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        boolean flag=true;
                        T_Text = input.getText().toString();
                        try {
                            D_Text = Double.parseDouble(input2.getText().toString());
                        } catch (NumberFormatException e) {
                            AlertDialog.Builder builder2 = new AlertDialog.Builder(MainActivity.this);
                            builder2.setTitle("Error");
                            builder2.setMessage("Try again but check that title won't be empty\ndistance is above 200m=0.2km and written in NUMBERS");
                            builder2.show();
                            flag=false;
                            e.printStackTrace();
                        }
                        if((T_Text.length()>0) && D_Text>=0.02)
                        {
                            i.putExtra("distance", D_Text);
                            i.putExtra("title", T_Text);
                            setResult(RESULT_OK, i);
                            finish();
                        }else {
                            if(flag){
                                AlertDialog.Builder builder2 = new AlertDialog.Builder(MainActivity.this);
                                builder2.setTitle("Error");
                                builder2.setMessage("Try again but check that title won't be empty and distance is above 200m=0.2km");
                                builder2.show();
                            }
                        }
                    }
                });
                builder.show();


            }
        });
    }
    @Override
    protected void onStart() {
        super.onStart();
        setUpMapIfNeeded();
        mGoogleApiClient.connect();
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (mGoogleApiClient.isConnected()) {
            mGoogleApiClient.disconnect();
        }
    }


    /*@Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
        mGoogleApiClient.connect();
    }

    @Override
    protected void onPause() {
        super.onPause();

        if (mGoogleApiClient.isConnected()) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
            mGoogleApiClient.disconnect();
        }
    }
     */
    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
        .addConnectionCallbacks(this)
        .addOnConnectionFailedListener(this)
        .addApi(LocationServices.API)
        .build();
    }
    /**
     * 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();
            }*/
        }
    }

    /**
     * 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 Marker oldMarker;
    private void setUpMap() {
        oldMarker=mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("activate gps!!"));
    }*/
    /*private void handleNewLocation(Location location) {
        Log.d(TAG, location.toString());

        double currentLatitude = location.getLatitude();
        double currentLongitude = location.getLongitude();
        oldMarker.remove();
        LatLng latLng = new LatLng(currentLatitude, currentLongitude);

        oldMarker=mMap.addMarker(new MarkerOptions().position(new LatLng(currentLatitude, currentLongitude)).title("Current Location"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        mMap.animateCamera(CameraUpdateFactory.zoomTo(15));
    }
     */
    Location Mloc;
    @Override
    public void onConnected(Bundle bundle) {
        double currentLatitude=0;
        double currentLongitude=0;
        Mloc = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        //Log.d(TAG, Mloc.toString());
        if(Mloc!= null)
        {
            currentLatitude = Mloc.getLatitude();
            currentLongitude = Mloc.getLongitude();
            //oldMarker.remove();
        }
        LatLng latLng = new LatLng(currentLatitude, currentLongitude);

        mMap.addMarker(new MarkerOptions().position(new LatLng(currentLatitude, currentLongitude)).title("Current Location"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        mMap.animateCamera(CameraUpdateFactory.zoomTo(15));


        /*if (location == null) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);*/
        /*}
        else {
            handleNewLocation(location);
        }*/
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        /*
         * Google Play services can resolve some errors it detects.
         * If the error has a resolution, try sending an Intent to
         * start a Google Play services activity that can resolve
         * error.
         */
        if (connectionResult.hasResolution()) {
            try {
                // Start an Activity that tries to resolve the error
                connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
                /*
                 * Thrown if Google Play services canceled the original
                 * PendingIntent
                 */
            } catch (IntentSender.SendIntentException e) {
                // Log the error
                e.printStackTrace();
            }
        } else {
            /*
             * If no resolution is available, display a dialog to the
             * user with the error.
             */
            Log.i(TAG, "Location services connection failed with code " + connectionResult.getErrorCode());
        }
    }

    /*@Override
    public void onLocationChanged(Location location) {
        handleNewLocation(location);
    }*/
}

このアクティビティは、私を追跡すること (位置情報の更新を取得すること) ではなく、アプリを開いた場所を表示することになっています。どうすればこれを解決できますか?

Answer 1

私も問題に直面しました。まず、GPS の初期化に時間がかかるため、最初の起動時に null 値が返される可能性があります。第二に、場所が変更されていることを確認するために GPS をチェックし続ける必要があります。幸いなことに、長い検索の後、現在の場所を取得するための最良の/堅牢なアプローチを提供する Stack Overflow で最終的に答えを見つけました。

場所の変更を取得するための MyLocation クラス、

public class MyLocation {
    Timer timer1;
    LocationManager lm;
    LocationResult locationResult;
    public boolean gps_enabled=false;
    boolean network_enabled=false;

    public boolean getLocation(Context context, LocationResult result)
    {
        //I use LocationResult callback class to pass location value from MyLocation to user code.
        locationResult=result;
        if(lm==null)
            lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);

        //exceptions will be thrown if provider is not permitted.
        try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);}catch(Exception ex){}
        try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);}catch(Exception ex){}

        //don't start listeners if no provider is enabled
        if(!gps_enabled && !network_enabled)
            return false;

        if(gps_enabled)
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
        if(network_enabled)
            lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
        timer1=new Timer();
        timer1.schedule(new GetLastLocation(), 20000);
        return true;
    }

    LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerNetwork);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    LocationListener locationListenerNetwork = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerGps);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    class GetLastLocation extends TimerTask {
        @Override
        public void run() {
             lm.removeUpdates(locationListenerGps);
             lm.removeUpdates(locationListenerNetwork);

             Location net_loc=null, gps_loc=null;
             if(gps_enabled)
                 gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
             if(network_enabled)
                 net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

             //if there are both values use the latest one
             if(gps_loc!=null && net_loc!=null){
                 if(gps_loc.getTime()>net_loc.getTime())
                     locationResult.gotLocation(gps_loc);
                 else
                     locationResult.gotLocation(net_loc);
                 return;
             }

             if(gps_loc!=null){
                 locationResult.gotLocation(gps_loc);
                 return;
             }
             if(net_loc!=null){
                 locationResult.gotLocation(net_loc);
                 return;
             }
             locationResult.gotLocation(null);
        }
    }

    public static abstract class LocationResult{
        public abstract void gotLocation(Location location);
    }
}

gotLocation()場所の更新を受け取るには、場所が変更されたときにデータを取得するメソッドをオーバーライドします。

MyLocation.LocationResult locationResult = new MyLocation.LocationResult() {
                        @Override
                        public void gotLocation(Location location) {
                            //Got the location!


                        }
                    };

                    MyLocation myLocation = new MyLocation();
                    myLocation.getLocation(getActivity(), locationResult);