url - 如何以单独的方法获取 Flutter Firebase 存储？

Question

我已成功将图像保存到我的 Firebase 存储引用中。现在我需要下载它。我看到的例子是以相同的方法上传和下载，使用相同的 StorageUploadTask 和这行代码......

final Uri downloadUrl = (await uploadTask.future).downloadUrl;

我的问题是如何从不需要 uploadTask.future 的单独方法获取 downloadUrl，因为我只在 FirebaseUser 更新其个人资料图片时上传图片？

Answer 1

StorageReference现在有Future<dynamic> getDownloadURL()方法。将结果重新键入字符串并将其与您的 NetworkImage 一起使用小部件:

import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';
import 'package:meta/meta.dart';

class FirestoreImage extends StatefulWidget {
  final StorageReference reference;
  final Widget fallback;
  final ImageProvider placeholder;

  FirestoreImage(
      {Key key,
      @required this.reference,
      @required this.fallback,
      @required this.placeholder});

  @override
  FirestoreImageState createState() =>
      FirestoreImageState(reference, fallback, placeholder);
}

class FirestoreImageState extends State<FirestoreImage> {
  final Widget fallback;
  final ImageProvider placeholder;

  String _imageUrl;
  bool _loaded = false;

  _setImageData(dynamic url) {
    setState(() {
      _loaded = true;
      _imageUrl = url;
    });
  }

  _setError() {
    setState(() {
      _loaded = false;
    });
  }

  FirestoreImageState(
      StorageReference reference, this.fallback, this.placeholder) {
    reference.getDownloadURL().then(_setImageData).catchError((err) {
      _setError();
    });
  }

  @override
  Widget build(BuildContext context) => _loaded
      ? FadeInImage(
          image: NetworkImage(_imageUrl),
          placeholder: placeholder,
        )
      : fallback;
}

旧答案:

我刚刚开始使用 Flutter (Dart) 进行开发，所以我的回答肯定不完美(甚至可能很糟糕)，但我是这样做的:

import 'dart:typed_data';

import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';

class FirestoreImage extends StatefulWidget {

  final StorageReference _reference;

  FirestoreImage(this._reference);

  @override
  FirestoreImageState createState() => FirestoreImageState(_reference);
}

class FirestoreImageState extends State<FirestoreImage> {

  Uint8List _imageData;

  _setImageData(Uint8List data) {
    setState(() {
      _imageData = data;
    });
  }

  FirestoreImageState(StorageReference reference) {
    reference
        .getData(0x3FFFFFFF)
        .then(_setImageData)
        .catchError((err) {});
  }

  @override
  Widget build(BuildContext context) =>
      _imageData == null ? Container() : Image.memory(_imageData);
}

现在你可以显示FirestoreImage调用new FirestoreImage(imageStorageReference) .也许有更好的方法来扩展 Image