如何使用Flutter将图像上传到Firebase

Question

我正在将image_picker库https://pub.dartlang.org/packages/image_picker用于选择/拍摄要上传的照片。到目前为止，代码已成功将映像成功上传到Firebase存储，唯一的问题是，在映像上传后，应用程序关闭了（并没有真正崩溃，它只是关闭了，而VS代码松开了与设备的连接）。代码如下：

 File _image;

  Future _takeProfilePicture() async{
    var image = await ImagePicker.pickImage(source: ImageSource.camera);

    setState((){
      _image = image;
    });
  }

  Future _selectProfilePicture() async{
    var image = await ImagePicker.pickImage(source: ImageSource.gallery);

    setState((){
      _image = image;
    });
  }

  Future<Null> _uploadProfilePicture() async{
    FirebaseUser user = await FirebaseAuth.instance.currentUser();

    final StorageReference ref = FirebaseStorage.instance.ref().child('${user.email}/${user.email}_profilePicture.jpg');
    final StorageUploadTask uploadTask = ref.putFile(_image);
    final Uri downloadUrl = (await uploadTask.future).downloadUrl;
  }

  void _selectAndUploadPicture() async{
    await _selectProfilePicture();
    await _uploadProfilePicture();
  }

  void _takeAndUploadPicture() async{
    await _takeProfilePicture();
    await _uploadProfilePicture();
  }

终端将显示以下内容：

W/Firestore( 6873): (0.6.6-dev) [Firestore]: The behavior for java.util.Date objects stored in Firestore is going to change AND YOUR APP MAY BREAK.
W/Firestore( 6873): To hide this warning and ensure your app does not break, you need to add the following code to your app before calling any other Cloud Firestore methods:
W/Firestore( 6873):
W/Firestore( 6873): FirebaseFirestore firestore = FirebaseFirestore.getInstance();
W/Firestore( 6873): FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder()
W/Firestore( 6873):     .setTimestampsInSnapshotsEnabled(true)
W/Firestore( 6873):     .build();
W/Firestore( 6873): firestore.setFirestoreSettings(settings);
W/Firestore( 6873):
W/Firestore( 6873): With this change, timestamps stored in Cloud Firestore will be read back as com.google.firebase.Timestamp objects instead of as system java.util.Date objects. So you will also need to update code expecting a java.util.Date to instead expect a Timestamp. For example:
W/Firestore( 6873):
W/Firestore( 6873): // Old:
W/Firestore( 6873): java.util.Date date = snapshot.getDate("created_at");
W/Firestore( 6873): // New:
W/Firestore( 6873): Timestamp timestamp = snapshot.getTimestamp("created_at");
W/Firestore( 6873): java.util.Date date = timestamp.toDate();
W/Firestore( 6873):
W/Firestore( 6873): Please audit all existing usages of java.util.Date when you enable the new behavior. In a future release, the behavior will be changed to the new behavior, so if you do not follow these steps, YOUR APP MAY BREAK.

我尝试从终端实施建议的Java代码，但是我似乎找不到使用cloud_firestore库https://pub.dartlang.org/packages/cloud_firestore在flutter中编写等效代码的方法，它没有与FirebaseFirestoreSettings等效的代码（或者我似乎无法找到一个）。有办法解决吗？

提前谢谢！

Answer 1

mmccabe答案的更新版本，该版本可与firebase_storage插件的1.0.4版一起使用

Future<String> _pickSaveImage(String imageId) async {
  File imageFile = await ImagePicker.pickImage(source: ImageSource.camera);
  StorageReference ref =
    FirebaseStorage.instance.ref().child(imageId).child("image.jpg");
  StorageUploadTask uploadTask = ref.putFile(imageFile);
  return await (await uploadTask.onComplete).ref.getDownloadURL();
}

到目前为止，您必须执行以下操作：

  

var downloadURL =（等待uploadTask.onComplete）.ref.getDownloadURL（）;

因为error: The getter 'future' isn't defined for the class 'StorageUploadTask'. (undefined_getter at [timetracker] lib/screens/image_detection.dart:63)

Answer 2

以下对我有用：

Future<Uri> _pickSaveImage(String imageId) async {
  File imageFile = await ImagePicker.pickImage(source: ImageSource.camera);
  StorageReference ref =
    FirebaseStorage.instance.ref().child(imageId).child("image.jpg");
  StorageUploadTask uploadTask = ref.putFile(imageFile);
  return (await uploadTask.future).downloadUrl;
}

Answer 3

Future<String> _pickSaveImage(String imageId) async {
  File imageFile = await ImagePicker.pickImage(source: ImageSource.camera);
  StorageReference ref =
    FirebaseStorage.instance.ref().child(imageId).child("image.jpg");
  StorageUploadTask uploadTask = ref.putFile(imageFile);
  return await (await uploadTask.onComplete).ref.getDownloadURL();
}

到目前为止，

这会导致错误：

  

返回等待状态（等待uploadTask.onComplete）.ref.getDownloadURL（）;

这不是

：

  

返回（等待uploadTask.onComplete）.ref.getDownloadURL（）;

错误消息：

The getter 'future' isn't defined for the class 'StorageUploadTask'. 

undefined_getter at [timetracker] lib/screens/image_detection.dart:63)

Answer 4

这对我有用...就我而言，我还需要获取下载URL并推送到firestore集合。经过阅读后，我发现最好使用StorageTaskSnapshot然后获取下载URL

uploadImage(File image) async {
    StorageReference reference =
             FirebaseStorage.instance.ref().child(image.path.toString());
    StorageUploadTask uploadTask = reference.putFile(image);

    StorageTaskSnapshot downloadUrl = (await uploadTask.onComplete);

    String url = (await downloadUrl.ref.getDownloadURL());


}