如果没有创建 Geofire，我如何检查 Geofire 以注销用户？

Question

问题总结： 我是 Android Studio 和 Firebase with Geofire 的新手，请多关照。我的目标是当用户在我的应用程序的地图屏幕上没有 Geofire 位置时注销用户。我不知道如何在我的 Geofire 中查询 "g"。如何查询 "g" 子节点以查看它是否已创建？如果未创建 "g"，则需要注销它们。所以目标是查询 "g" 并创建方法，如果 "g" 为空，则将用户注销。

我做过的事情： 许多 Whosebug 帖子没有使用 Android Studio。我确实找到了这个 I have inserted location using geofire in firebase but it did not resolve my issue. I also tried

onLocationChanges 是我添加在线供应商的地方，也是我想检查是否已创建 "g" 的地方。

 @Override
public void onLocationChanged(Location location) {


    // Adds VendorOnline Child to Firebase when Vendor is On This Activity
    addVendorOnline();
    // Log user out if they are on the map screen without a "VendorOnline" Uid
    logVendorOutIfBuggy();

}

这是创建在线商贩并检查是否已创建"g"的方法：

 private void addVendorOnline(){

    if (FirebaseAuth.getInstance().getCurrentUser() != null) {

        String vendorId = FirebaseAuth.getInstance().getCurrentUser().getUid();
        DatabaseReference vendorIdReference = FirebaseDatabase.getInstance().getReference("VendorOnline");
        GeoFire vendorGeoFire = new GeoFire(vendorIdReference);
        vendorGeoFire.setLocation(vendorId, new GeoLocation(lastLocation.getLatitude(), lastLocation.getLongitude()));
    }
    }  


   // Log user out if for some reason they do not have a "g" child but are on the map screen.
   private void logVendorOutIfBuggy() {
   DatabaseReference ref = FirebaseDatabase.getInstance().getReference("g");

    if(ref == null){

        Toast.makeText(VendorMapsActivity.this, "Error", Toast.LENGTH_LONG).show();

        FirebaseAuth.getInstance().signOut();
    }

我期望发生的事情和实际发生的事情： 如果 "g" 等于 null，我希望用户注销，但现在用户不退出。

Answer 1

这是调用 getLocation 以查看供应商是否注册了位置的示例。

来自 LocationCallback.onLocationResult 的 javadocs :

This method is called with the current location of the key. location will be null if there is no location stored in GeoFire for the key.

        final String vendorKey = "someVendorKey";
        geoFire.getLocation(vendorKey, new LocationCallback() {
            @Override
            public void onLocationResult(String key, GeoLocation location) {
                if (key.compareTo(vendorKey) == 0) {
                    if (location == null) {
                        // vendor has not logged a location yet (or it was removed)
                    }
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

如果没有创建 Geofire，我如何检查 Geofire 以注销用户？

How can I check Geofire to log user out if no Geofire was created?

android

geofire

firebase-realtime-database