如何使用Google地图从我当前位置开始移动路径

Question

当我从当前位置移动时,我正在尝试绘制路线.我在动态绘制路线时面临一个大问题请帮我解决.我在我的地图中的当前位置有标记.一旦我开始移动,我希望地图开始在我移动的路径中绘制线条.我没有两个固定点.任何人都可以为我提供解决方案.我在SO中看到很多答案,它在两个固定点之间绘制路径.但这里只有我的初步观点是固定的.我目前可以在我的应用中获取当前位置.我尝试使用以下代码,但getLocationManager()导致错误.我正在使用Android Studio.

更新的代码:

我的活动:

import android.content.Context;
import android.content.SharedPreferences;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.util.Xml;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.PendingResult;
import com.google.android.gms.common.api.Status;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
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.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 com.google.maps.android.ui.IconGenerator;

import org.xmlpull.v1.XmlSerializer;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.StringWriter;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Locale;

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

    private static final String TAG = "MainActivity";
    private static final long INTERVAL = 1000 * 60 * 1; //1 minute
    private static final long FASTEST_INTERVAL = 1000 * 60 * 1; // 1 minute
    private LocationRequest mLocationRequest;
    private GoogleApiClient mGoogleApiClient;
    private Location mCurrentLocation;
    private String mLastUpdateTime;
    private String city = "";
    private String country = "";
    private String area = "";
    private String title;
    private String requiredArea = "";
    private GoogleMap googleMap;
    private List<Address> addresses;


    protected void createLocationRequest() {
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(INTERVAL);
        mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate ...............................");
        //show error dialog if GoolglePlayServices not available
        if (!isGooglePlayServicesAvailable()) {

            Toast.makeText(this, "Google Play Services is not available", Toast.LENGTH_LONG).show();

            finish();
        }
        createLocationRequest();
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

        setContentView(R.layout.activity_main);
        SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);

        googleMap = fm.getMap();
        googleMap.setMyLocationEnabled(true);
        googleMap.setOnMyLocationButtonClickListener(new GoogleMap.OnMyLocationButtonClickListener() {
            @Override
            public boolean onMyLocationButtonClick() {

                Toast.makeText(getApplicationContext(), "Location button has been clicked", Toast.LENGTH_LONG).show();
                return true;
            }
        });
        googleMap.getUiSettings().setZoomControlsEnabled(true);
        googleMap.getUiSettings().setAllGesturesEnabled(true);


    }

    @Override
    public void onStart() {
        super.onStart();
        Log.d(TAG, "onStart fired ..............");
        mGoogleApiClient.connect();
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.d(TAG, "onStop fired ..............");
        mGoogleApiClient.disconnect();
        Log.d(TAG, "isConnected ...............: " + mGoogleApiClient.isConnected());
    }

    private boolean isGooglePlayServicesAvailable() {
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (ConnectionResult.SUCCESS == status) {
            return true;
        } else {
            GooglePlayServicesUtil.getErrorDialog(status, this, 0).show();
            Toast.makeText(getApplicationContext(), "Google Play Services is not Available", Toast.LENGTH_LONG).show();
            return false;
        }
    }

    @Override
    public void onConnected(Bundle bundle) {
        Log.d(TAG, "onConnected - isConnected ...............: " + mGoogleApiClient.isConnected());
        startLocationUpdates();
    }

    protected void startLocationUpdates() {
        PendingResult<Status> pendingResult = LocationServices.FusedLocationApi.requestLocationUpdates(
                mGoogleApiClient, mLocationRequest, this);
        Log.d(TAG, "Location update started ..............: ");
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.d(TAG, "Connection failed: " + connectionResult.toString());
    }

    @Override
    public void onLocationChanged(Location location) {
        Log.d(TAG, "Firing onLocationChanged..............................................");
        mCurrentLocation = location;
        mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
        addMarker();
        float accuracy = location.getAccuracy();
        Log.d("iFocus", "The amount of accuracy is " + accuracy);
        double latitude = location.getLatitude();
        double longitude = location.getLongitude();
        Bundle extras = location.getExtras();
        Boolean has = location.hasAccuracy();
        String provider = location.getProvider();
        Long time = location.getTime();

//        Location locationB = new Location("Begur");
//        double lati = 12.8723;
//        double longi =  77.6329;
//        locationB.setLatitude(lati);
//        locationB.setLongitude(longi);
//        Float distance = location.distanceTo(locationB);

        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(time);

        int mYear = calendar.get(Calendar.YEAR);
        int mMonth = calendar.get(Calendar.MONTH) + 1;
        int mDay = calendar.get(Calendar.DAY_OF_MONTH);

        String formattedTime = mDay + ":" + mMonth + ":" + mYear;
        Log.d("iFocus", "The name of provider is " + provider);
        Log.d("iFocus", "The value of has is " + has);
        Log.d("iFocus", "The value of extras is " + extras);
        Log.d("iFocus", "The value of Month is " + mMonth);
        Log.d("iFocus", "The value of Day is " + mDay);
        Log.d("iFocus", "The value of Year is " + mYear);
        Log.d("iFocus", "The value of Time is " + formattedTime);
        //Log.d("iFocus", "The value of distance is "+distance);

        LatLng latLng = new LatLng(latitude, longitude);

        Geocoder geocoder = new Geocoder(this, Locale.getDefault());

        try {
            addresses = geocoder.getFromLocation(latitude, longitude, 1);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String cityName = addresses.get(0).getAddressLine(0);
        String stateName = addresses.get(0).getAddressLine(1);
        String countryName = addresses.get(0).getAddressLine(2);

        String[] splittedStateName = stateName.split(",");
        requiredArea = splittedStateName[2];
        Log.d("iFocus", "The value of required area is " + requiredArea);

        city = addresses.get(0).getLocality();
        area = addresses.get(0).getSubLocality();
        String adminArea = addresses.get(0).getAdminArea();
        String premises = addresses.get(0).getPremises();
        String subAdminArea = addresses.get(0).getSubAdminArea();
        String featureName = addresses.get(0).getFeatureName();
        String phone = addresses.get(0).getPhone();
        country = addresses.get(0).getCountryName();
        Log.d("iFocus", "The name of city is " + city);
        Log.d("iFocus", "The name of area is " + area);
        Log.d("iFocus", "The name of country is " + country);
        Log.d("iFocus", "The value of cityName is " + cityName);
        Log.d("iFocus", "The value of StateName is " + stateName);
        Log.d("iFocus", "The value of CountryName is " + countryName);

        Toast.makeText(this, cityName + " " + stateName + " " + countryName, Toast.LENGTH_LONG).show();

        SharedPreferences sharedPreferences = getSharedPreferences("MyValues", MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString("CITY", cityName);
        editor.putString("STATE", stateName);
        editor.putString("COUNTRY", countryName);
        editor.commit();

        TextView mapTitle = (TextView) findViewById(R.id.textViewTitle);

        if (requiredArea != "" && city != "" && country != "") {
            title = mLastUpdateTime.concat(", " + requiredArea).concat(", " + city).concat(", " + country);
        }
        else {
            title = mLastUpdateTime.concat(", " + area).concat(", " + city).concat(", " + country);
        }
        mapTitle.setText(title);
        addMarker();// newly added

        final String xmlFile = "userData.xml";

        try {
            // FileOutputStream fos = new  FileOutputStream("userData.xml");
            FileOutputStream fos = openFileOutput(xmlFile, Context.MODE_PRIVATE);
            XmlSerializer xmlSerializer = Xml.newSerializer();
            StringWriter writer = new StringWriter();
            xmlSerializer.setOutput(writer);
            xmlSerializer.startDocument("UTF-8", true);
            xmlSerializer.startTag(null, "userData");
            xmlSerializer.startTag(null, "Time");
            xmlSerializer.text(mLastUpdateTime);
            xmlSerializer.endTag(null, "Time");
            xmlSerializer.startTag(null, "Area");
            if (requiredArea != "") {
                xmlSerializer.text(requiredArea);
            }
            else {
                xmlSerializer.text(area);
            }
            xmlSerializer.endTag(null, "Area");
            xmlSerializer.startTag(null, "City");
            xmlSerializer.text(city);
            xmlSerializer.endTag(null, "City");
            xmlSerializer.endTag(null, "userData");
            xmlSerializer.endDocument();
            xmlSerializer.flush();
            String dataWrite = writer.toString();
            fos.write(dataWrite.getBytes());
            fos.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        String dir = getFilesDir().getAbsolutePath();
        Log.d("Pana", "The value of Dir is "+dir);

    }

    private void addMarker() {
        MarkerOptions options = new MarkerOptions();

        // following four lines requires 'Google Maps Android API Utility Library'
        // https://developers.google.com/maps/documentation/android/utility/
        // I have used this to display the time as title for location markers
        // you can safely comment the following four lines but for this info
        IconGenerator iconFactory = new IconGenerator(this);
        iconFactory.setStyle(IconGenerator.STYLE_PURPLE);
        // options.icon(BitmapDescriptorFactory.fromBitmap(iconFactory.makeIcon(mLastUpdateTime + requiredArea + city)));
        options.icon(BitmapDescriptorFactory.fromBitmap(iconFactory.makeIcon(requiredArea + ", " + city)));
        options.anchor(iconFactory.getAnchorU(), iconFactory.getAnchorV());
        LatLng currentLatLng = new LatLng(mCurrentLocation.getLatitude(), mCurrentLocation.getLongitude());
        options.position(currentLatLng);
        Marker mapMarker = googleMap.addMarker(options);
        long atTime = mCurrentLocation.getTime();
        mLastUpdateTime = DateFormat.getTimeInstance().format(new Date(atTime));
        String title = mLastUpdateTime.concat(", " + requiredArea).concat(", " + city).concat(", " + country);
        mapMarker.setTitle(title);


        TextView mapTitle = (TextView) findViewById(R.id.textViewTitle);
        mapTitle.setText(title);

        Log.d(TAG, "Marker added.............................");
        googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(currentLatLng,
                13));
        Log.d(TAG, "Zoom done.............................");
    }

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

    protected void stopLocationUpdates() {
        LocationServices.FusedLocationApi.removeLocationUpdates(
                mGoogleApiClient, this);
        Log.d(TAG, "Location update stopped .......................");
    }

    @Override
    public void onResume() {
        super.onResume();
        if (mGoogleApiClient.isConnected()) {
            startLocationUpdates();
            Log.d(TAG, "Location update resumed .....................");
        }
    }
}

我试图在我的代码中添加此方法来绘制线但在getLocationManager()中给出错误;

private void addLocationListener(LocationListener locationListener) {
    LocationProvider locationProvider = getLocationManager().getProvider(LocationManager.GPS_PROVIDER);
    getLocationManager().requestLocationUpdates(locationProvider.getName(), LOCATION_UPDATE_INTERVAL,
                LOCATION_UPDATE_MIN_DISTANCE, locationListener);
}

private LocationManager getLocationManager() {
    return (LocationManager)context.getSystemService(Context.LOCATION_SERVICE);
}

private void startGpsListening(Location start) {
    this.startLocation = start;
    addLocationListener(new MyLocationListener());
}

private Location startLocation = new Location("");

private class MyLocationListener extends LocationListener {

    public void onLocationChanged(Location location) {

    }
    ...
}

Answer 1

似乎最好的实现方式是使用a ArrayList<LatLng>来存储给定的每个点onLocationChanged().然后,每次获得新点时,重新绘制线条.

首先,导入绘制线条所需的内容:

import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;

为ArrayList和Polyline创建成员变量:

private ArrayList<LatLng> points; //added
Polyline line; //added

初始化points中onCreate():

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    points = new ArrayList<LatLng>(); //added
    //...............

然后,在onLocationChanged(),将您获得的每个点添加到ArrayList:

@Override
public void onLocationChanged(Location location) {
      double latitude = location.getLatitude();
      double longitude = location.getLongitude();
      LatLng latLng = new LatLng(latitude, longitude); //you already have this

      points.add(latLng); //added

      redrawLine(); //added

}

从这个答案中,定义你的redrawLine()方法.
删除所有其他呼叫addMarker(),因为您将clear()在地图上呼叫,这将删除所有标记和折线.

private void redrawLine(){

    googleMap.clear();  //clears all Markers and Polylines

    PolylineOptions options = new PolylineOptions().width(5).color(Color.BLUE).geodesic(true);
    for (int i = 0; i < points.size(); i++) {
        LatLng point = points.get(i);
        options.add(point);
    }
    addMarker(); //add Marker in current position
    line = googleMap.addPolyline(options); //add Polyline
}

编辑:您可能还希望拨打位置更改回调之间的最小距离(以米为单位).

private static final String TAG = "MainActivity";
private static final long INTERVAL = 1000 * 60 * 1; //1 minute
private static final long FASTEST_INTERVAL = 1000 * 60 * 1; // 1 minute
private static final float SMALLEST_DISPLACEMENT = 0.25F; //quarter of a meter

致电setSmallestDisplacement():

protected void createLocationRequest() {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(INTERVAL);
    mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
    mLocationRequest.setSmallestDisplacement(SMALLEST_DISPLACEMENT); //added
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}

这应该足以让你开始.您可能需要微调位置更改回调的频率以获得所需的结果.可能还有更多,但你可以找到边缘情况并在测试后修复它们.