如何从 Firebase 存储文件中获取 url？

Question

我想从 firebase 存储中检索 URL 的 Uint8List 图像。但我不能那样做。它打印快照，而不是 url。请帮忙

我的代码：

 void _storeSignature() async {
        try {
          final  Uint8List? signature = await exportSignature();
    
          final FirebaseStorage? storage = FirebaseStorage.instance;
          final String? pictureUrl =
              "signature/${DateTime.now().millisecondsSinceEpoch.toString()}.png";
    
          final ref = storage!.ref().child(pictureUrl!);
          final uploadTask = ref.putData(signature!);
          final downurl = await uploadTask.whenComplete(() {
            return ref.getDownloadURL();
          });
          final url = downurl.toString();
    
          print(url);
    
        } catch (e) {
          rethrow;
        }
      }

Answer 1

调用 ref.getDownloadURL()

时，URL 必须 await

改变

return ref.getDownloadURL();

进入

return await ref.getDownloadURL();

Answer 2

UploadTask class 扩展了 Future，因此您也可以在那里使用 await：

await ref.putData(signature!);
final downurl = await ref.getDownloadURL();
final url = downurl.toString();