安裝最新版Android Studio 3.2版本
建立一個專案
設定API 22:Android 5.1 (L)版本
開啟google map 專案
Google Maps API kml
裡有一串註解

 <!--
    TODO: Before you run your application, you need a Google Maps API key.

    To get one, follow this link, follow the directions and press "Create" at the end:

    https://console.developers.google.com/flows/enableapi?apiid=maps_android_backend&keyType=CLIENT_SIDE_ANDROID&r=我的專案的資料

    You can also add your credentials to an existing key, using these values:

    Package name:
    F5:87:76:41:94:C3:3B:84:5B:C1:7C:BA:73:B2:D7:13:1D:96:C7:7C

    SHA-1 certificate fingerprint:
    F5:87:76:41:94:C3:3B:84:5B:C1:7C:BA:73:B2:D7:13:1D:96:C7:7C

    Alternatively, follow the directions here:
    https://developers.google.com/maps/documentation/android/start#get-key

    Once you have your key (it starts with "AIza"), replace the "google_maps_key"
    string in this file.
    -->

點擊連結後 我新增了一個key

下方是
有我的KEY

build.grade 設定是這樣

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "com.shijung.travel"
        minSdkVersion 22
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.google.android.gms:play-services-location:15.0.1'
    implementation 'com.google.android.gms:play-services-maps:15.0.1'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

加入了要用的 google 的東西 也按了sync 運作是成功的

但卻沒有地圖

我的code
MapsActivity.java

package com.shijung.travel;

import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Location;
import android.support.annotation.MainThread;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.util.Log;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdate;
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.MarkerOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;


public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;
    private static int LOCATION_PERMISSION_REQUEST_CODE = 1001;
    private static boolean rLocationGranted = false;
    private FusedLocationProviderClient mFusedLocationProvider;

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


        if (chkPlayService()) {
            initialMap();
            if (rLocationGranted) {
                // 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);
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        //super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        rLocationGranted = false;
        switch (requestCode) {
            case 1001:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    for (int i = 0; i < grantResults.length; i++) {
                        if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
                            rLocationGranted = false;
                            return;
                        }
                    }
                    rLocationGranted = true;
                }
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    rLocationGranted = false;
                    //map initial;
                }
                if (grantResults.length > 0 && grantResults[1] == PackageManager.PERMISSION_GRANTED) {
                    rLocationGranted = true;
                    //map initial;
                }
        }
    }

    private void initialMap() {
        String[] permissioins = {Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION};
        if ((ContextCompat.checkSelfPermission(this.getApplicationContext(), permissioins[0])
                == PackageManager.PERMISSION_GRANTED) ||
                (ContextCompat.checkSelfPermission(this.getApplicationContext(), permissioins[1])
                        == PackageManager.PERMISSION_GRANTED)) {
            //可以取得 FINE LOCATION
            rLocationGranted = true;
        } else {
            ActivityCompat.requestPermissions(this, permissioins,
                    LOCATION_PERMISSION_REQUEST_CODE);
        }
    }

    private void getDeviceLocation() {
        mFusedLocationProvider = LocationServices.getFusedLocationProviderClient(this);
        try {
            if (rLocationGranted) {
                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;
                }
                Task location = mFusedLocationProvider.getLastLocation();
                location.addOnCompleteListener(new OnCompleteListener() {
                    @Override
                    public void onComplete(@NonNull Task task) {
                        if(task.isSuccessful()){
                            Location mLocation = (Location) task.getResult();
                            mMap.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(mLocation.getLatitude(),mLocation.getLongitude())));
                        }
                    }
                });
            }
            //if(ActivityCompat.checkSelfPermission((this,Manifest.permission.ACCESS_FINE_LOCATION))
        }catch(Exception ex){
            Log.e("Location Error",ex.getMessage());
        }
    }
    private  boolean chkPlayService(){
        int avai = GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(MapsActivity.this);
        if(avai ==ConnectionResult.SUCCESS){
            Log.i("Map Test","Version is Fine");
            return  true;
        }else{
            Toast.makeText(this,"版本不符合，無法執行MAP",Toast.LENGTH_LONG).show();
            return  false;
        }
    }

    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        getDeviceLocation();
        // Add a marker in Sydney and move the camera
        //LatLng sydney = new LatLng(-34, 151);
       // mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        //mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));
    }
}