如何从扑扑到Firebase存储的图像的Firebase实时数据库中获取下载URL

Question

我通过下面给出的代码将图像从移动设备上传到Firebase存储，问题是我想向最终用户显示上传的图像，但URLs.json文件返回null，这是因为firebase实时数据库是空值。那么如何将图像存储在实时数据库中并获取URLs.json文件以在应用程序中调用它，或者如何获取URLs.json文件进行Firebase存储呢？

上传到Firebase存储-

FirebaseStorage _storage = FirebaseStorage.instance;

  Future uploadPic(File file) async {
    if (file != null) {
      setState(() {
        isLoading = true;
      });
      var rng = new Random();
      String randomId = rng.nextInt(10000000).toString();
      String fileName = "" +
          randomId +
          '${file.absolute.path.endsWith('.png') ? '.png' : '.jpg'}';

      StorageReference reference = _storage.ref().child(fileName);
      StorageUploadTask uploadTask = reference.putFile(file);

      await (await uploadTask.onComplete).ref.getDownloadURL().then((url) {
        setState(() {
          _imageUrl = url.toString();
          updateRTDatabaseWithURL(_imageUrl, randomId);
          showInSnackBar('File Uploaded Successfully');

          _image = null;
          isLoading = false;
        });
      });
    } else
      showInSnackBar('Please, Choose a File');
  }

  List<dynamic> urlList;

  updateRTDatabaseWithURL(imageURL, id) async {
     var url = 'https://<Project_Name>.firebaseio.com/URLs.json';

    await http.get(url).then((res) {
      if (res.statusCode == 200) {
        var resData = json.decode(res.body);
        setState(() {
          urlList = resData['URL'];
        });
        urlList.add(imageURL);

        FirebaseDatabase()
            .reference()
            .child('URLs')
            .update({'URL': urlList}).then((v) {
          showInSnackBar('URL added to the Firebase List');
        }).catchError((e) {
          print(e.message);
        });
      }
    });
  }