将文件上传到firebase存储Flutter后无法获取下载链接答案

【问题标题】：Cannot get the download link after uploading files to firebase storage Flutter将文件上传到firebase存储Flutter后无法获取下载链接
【发布时间】：2022-08-13 22:06:19
【问题描述】：

所以这是我的文件选择和文件上传代码

class Storage with ChangeNotifier {
  PlatformFile? pickedFile;
  UploadTask? uploadTask;

  Future uploadFile() async {
    final path = \'files/${pickedFile!.name}.png\';
    final file = File(pickedFile!.path!);

    final ref = FirebaseStorage.instance.ref().child(path);
    ref.putFile(file);

    

    try {
      final snapshot = await uploadTask!.whenComplete(() {});
      final urlDownload = await snapshot.ref.getDownloadURL();
      print(urlDownload);
    } catch (e) {
      print(\"this is the error $e \" );
    }
  }

  void pickFile() async {
    FilePickerResult? result = await FilePicker.platform.pickFiles();

    if (result != null) {
      File file = File(result.files.single.path!);
      pickedFile = result.files.first;
    } else {
      print(\"no image picked\");
    }}}

该代码适用于上传图像，但之后我没有得到任何下载链接，错误是“用于空值的空检查运算符”我不知道如何修复它，我还是这个主题的新手，请帮助

标签： flutter firebase firebase-storage

【解决方案1】：

我得到了答案，需要将uploadFile方法更改为此

Future uploadFile() async {
final path = 'files/${pickedFile!.name}.png';
final file = File(pickedFile!.path!);

FirebaseStorage storage = FirebaseStorage.instance;
Reference ref = storage.ref().child(path);
UploadTask uploadTask = ref.putFile(file);
uploadTask.then((res) {
  res.ref.getDownloadURL();
});



try {
  final snapshot = await uploadTask.whenComplete(() {});
  final urlDownload = await snapshot.ref.getDownloadURL();
  print(urlDownload);
} catch (e) {
  print("this is the error $e " );
}

}

【讨论】：