读取 longlat 数据实时 Firebase 和实现以映射 Android Studio

Posted 2023-05-07

【中文标题】读取 longlat 数据实时 Firebase 和实现以映射 Android Studio

【英文标题】：Read longlat data realtime Firebase and implementation to map Android Studio

【发布时间】：2019-01-08 15:41:27

【问题描述】：

你能帮我解决这个问题吗？

我想从 Firebase 实时读取数据并在地图上显示标记。 longlat 标记数据是从 firebase 而非代码中实时读取的。 Firebase 更改了地图中的数据。

这是我的代码：

public class mapmotor1 extends FragmentActivity implements OnMapReadyCallback 

private GoogleMap mMap;
private FirebaseDatabase firebaseDatabase;
private DatabaseReference databaseReference;
private static final int LOCATION_REQUEST = 500;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mapmotor1);

    // 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);

    firebaseDatabase = FirebaseDatabase.getInstance();
    databaseReference = firebaseDatabase.getReference().child("proyek-akhir-c93d7").child("1");



/**
 * 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;
    firebaseDatabase = FirebaseDatabase.getInstance();
    databaseReference = firebaseDatabase.getReference().child("proyek-akhir-c93d7").child("1");
   **//this is replaced what**
    LatLng device = new LatLng (-6.97455, 107.6326);

    mMap.addMarker(new MarkerOptions().position(device).title("Here"));

    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(device, 15));
    mMap.animateCamera(CameraUpdateFactory.zoomIn());
    mMap.animateCamera(CameraUpdateFactory.zoomTo(15), 2000, null);


@SuppressLint("MissingPermission")
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) 
    switch (requestCode)
        case LOCATION_REQUEST:
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                mMap.setMyLocationEnabled(true);
            
            break;
    

【参考方案1】：

假设proyek-akhir-c93d7是你的Firebase根，要获取1节点下的经纬度，请使用以下代码行：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference oneRef = rootRef.child("1");
ValueEventListener valueEventListener = new ValueEventListener() 
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) 
        double latitude = dataSnapshot.child("latitude").getValue(Double.class);
        double longitude = dataSnapshot.child("longitude").getValue(Double.class);
        //Do what you need to do with the latitude and longitude
        Log.d("TAG", latitude + ", " + longitude);
    

    @Override
    public void onCancelled(DatabaseError databaseError) 
;
oneRef.addListenerForSingleValueEvent(valueEventListener);

您的 logcat 中的输出将是：

-6.97455, 107.6326

【讨论】：

"oneRef.addListenerForSingleValueEvent(valueEventListener);"代码放在哪里？在 public void onCancelled 或 dataonchange 之下？

不，就在你在我的代码中看到的位置，就在最后一个花括号和分号之后，对吧？有用吗？