我在谷歌Map上搜索如何画路线方向，找到了一些链接，但是代码中没有画出两个地方之间的路径，有人能帮我画出两个地方之间的路径吗？我用的是安卓studio 2.1，编译sdk版本24
activity_maps.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MapsActivity">

    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:map="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.shyamali.maptest.MapsActivity"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="bottom"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#cc3b60a7"
            android:orientation="horizontal">

            <Button
                android:id="@+id/buttonSetFrom"
                android:text="Set From"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

            <Button
                android:id="@+id/buttonSetTo"
                android:text="Set To"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

            <Button
                android:id="@+id/buttonCalcDistance"
                android:text="Calc Distance"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

        </LinearLayout>
    </LinearLayout>
</FrameLayout>

MapsActivity.java

package com.example.shyamali.maptest;

import android.Manifest;
import android.app.ProgressDialog;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.location.Location;
import android.net.Uri;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
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.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
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.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;
import com.google.maps.android.SphericalUtil;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class MapsActivity extends FragmentActivity implements
        OnMapReadyCallback, GoogleApiClient.ConnectionCallbacks,GoogleApiClient.OnConnectionFailedListener,GoogleMap.OnMarkerDragListener,GoogleMap.OnMapLongClickListener,View.OnClickListener {

    //Our Map
    private GoogleMap mMap;

    //To store longitude and latitude from map
    private double longitude;
    private double latitude;

    //From -> the first coordinate from where we need to calculate the distance
    private double fromLongitude;
    private double fromLatitude;

    //To -> the second coordinate to where we need to calculate the distance
    private double toLongitude;
    private double toLatitude;

    //Google ApiClient
    private GoogleApiClient googleApiClient;

    //Our buttons
    private Button buttonSetTo;
    private Button buttonSetFrom;
    private Button buttonCalcDistance;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        //Initializing googleapi client
        // ATTENTION: This "addApi(AppIndex.API)"was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        googleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .addApi(AppIndex.API).build();

        buttonSetTo = (Button) findViewById(R.id.buttonSetTo);
        buttonSetFrom = (Button) findViewById(R.id.buttonSetFrom);
        buttonCalcDistance = (Button) findViewById(R.id.buttonCalcDistance);

        buttonSetTo.setOnClickListener(this);
        buttonSetFrom.setOnClickListener(this);
        buttonCalcDistance.setOnClickListener(this);
    }

    @Override
    protected void onStart() {
        googleApiClient.connect();
        super.onStart();
        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        Action viewAction = Action.newAction(
                Action.TYPE_VIEW, // TODO: choose an action type.
                "Maps Page", // TODO: Define a title for the content shown.
                // TODO: If you have web page content that matches this app activity's content,
                // make sure this auto-generated web page URL is correct.
                // Otherwise, set the URL to null.
                Uri.parse("http://host/path")
        );
        AppIndex.AppIndexApi.start(googleApiClient, viewAction);
    }

    @Override
    protected void onStop() {
        googleApiClient.disconnect();
        super.onStop();
        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        Action viewAction = Action.newAction(
                Action.TYPE_VIEW, // TODO: choose an action type.
                "Maps Page", // TODO: Define a title for the content shown.
                // TODO: If you have web page content that matches this app activity's content,
                // make sure this auto-generated web page URL is correct.
                // Otherwise, set the URL to null.
                Uri.parse("http://host/path")
        );
        AppIndex.AppIndexApi.end(googleApiClient, viewAction);
    }

    //Getting current location
    private void getCurrentLocation() {
        mMap.clear();
        //Creating a location object
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        Location location = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);
        if (location != null) {
            //Getting longitude and latitude
            longitude = location.getLongitude();
            latitude = location.getLatitude();

            //moving the map to location
            moveMap();
        }
    }

    //Function to move the map
    private void moveMap() {
        //Creating a LatLng Object to store Coordinates
        LatLng latLng = new LatLng(latitude, longitude);

        //Adding marker to map
        mMap.addMarker(new MarkerOptions()
                .position(latLng) //setting position
                .draggable(true) //Making the marker draggable
                .title("Current Location")); //Adding a title

        //Moving the camera
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        //Animating the camera
        mMap.animateCamera(CameraUpdateFactory.zoomTo(15));
    }

    public String makeURL (double sourcelat, double sourcelog, double destlat, double destlog ){
        StringBuilder urlString = new StringBuilder();
        urlString.append("https://maps.googleapis.com/maps/api/directions/json");
        urlString.append("?origin=");// from
        urlString.append(Double.toString(sourcelat));
        urlString.append(",");
        urlString
                .append(Double.toString( sourcelog));
        urlString.append("&destination=");// to
        urlString
                .append(Double.toString( destlat));
        urlString.append(",");
        urlString.append(Double.toString(destlog));
        urlString.append("&sensor=false&mode=driving&alternatives=true");
        urlString.append("&key=AIzaSyCJVpM7-ayGMraxFRzq4U8Dt1uRNsmiaws");
        return urlString.toString();
    }

    private void getDirection(){
        //Getting the URL
        String url = makeURL(fromLatitude, fromLongitude, toLatitude, toLongitude);

        //Showing a dialog till we get the route
        final ProgressDialog loading = ProgressDialog.show(this, "Getting Route", "Please wait...", false, false);

        //Creating a string request
        StringRequest stringRequest = new StringRequest(url,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        loading.dismiss();
                        //Calling the method drawPath to draw the path
                        drawPath(response);
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        loading.dismiss();
                    }
                });

        //Adding the request to request queue
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(stringRequest);
    }

    //The parameter is the server response
    public void drawPath(String  result) {
        //Getting both the coordinates
        LatLng from = new LatLng(fromLatitude,fromLongitude);
        LatLng to = new LatLng(toLatitude,toLongitude);

        //Calculating the distance in meters
        Double distance = SphericalUtil.computeDistanceBetween(from, to);

        //Displaying the distance
        Toast.makeText(this,String.valueOf(distance+" Meters"),Toast.LENGTH_SHORT).show();

        try {
            //Parsing json
            final JSONObject json = new JSONObject(result);
            JSONArray routeArray = json.getJSONArray("routes");
            JSONObject routes = routeArray.getJSONObject(0);
            JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
            String encodedString = overviewPolylines.getString("points");
            List<LatLng> list = decodePoly(encodedString);
            Polyline line = mMap.addPolyline(new PolylineOptions()
                    .addAll(list)
                    .width(20)
                    .color(Color.RED)
                    .geodesic(true)
            );

        }
        catch (JSONException e) {

        }
    }

    private List<LatLng> decodePoly(String encoded) {
        List<LatLng> poly = new ArrayList<LatLng>();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;

        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            LatLng p = new LatLng( (((double) lat / 1E5)),
                    (((double) lng / 1E5) ));
            poly.add(p);
        }

        return poly;
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        LatLng latLng = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(latLng).draggable(true));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        mMap.setOnMarkerDragListener(this);
        mMap.setOnMapLongClickListener(this);
    }

    @Override
    public void onConnected(Bundle bundle) {
        getCurrentLocation();
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {

    }

    @Override
    public void onMapLongClick(LatLng latLng) {
        //Clearing all the markers
        mMap.clear();
        //Adding a new marker to the current pressed position
        mMap.addMarker(new MarkerOptions()
                .position(latLng)
                .draggable(true));

        latitude = latLng.latitude;
        longitude = latLng.longitude;
    }

    @Override
    public void onMarkerDragStart(Marker marker) {

    }

    @Override
    public void onMarkerDrag(Marker marker) {

    }

    @Override
    public void onMarkerDragEnd(Marker marker) {
        //Getting the coordinates
        latitude = marker.getPosition().latitude;
        longitude = marker.getPosition().longitude;

        //Moving the map
        moveMap();
    }

    @Override
    public void onClick(View v) {
        if(v == buttonSetFrom){
            fromLatitude = latitude;
            fromLongitude = longitude;
            Toast.makeText(this,"From set",Toast.LENGTH_SHORT).show();
        }

        if(v == buttonSetTo){
            toLatitude = latitude;
            toLongitude = longitude;
            Toast.makeText(this,"To set",Toast.LENGTH_SHORT).show();
        }

        if(v == buttonCalcDistance){
            getDirection();
        }
    }
}