Question

我正在尝试将自定义对象上载到Firebase Firestore，但是Firestore对象应包含下载图像网址。我要做的是先上传图像，等待图像完成，获取对下载URL的引用，更新我的自定义类，然后将其上传到Firestore。然后，我想在最后一次上传（上传到Firestore）完成时通知我的视图。我当时正在考虑通过返回任务来做到这一点。这是我要上传的图片：

ref.putFile(file).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                @Override
                public void onSuccess(Uri uri) {
                    //use uri to update object and then upload to firestore

                       mObject.setImageUri(uri)
                       uploadToFirestore(myObject);
                    }
                    Log.d(TAG, "onSuccess: uri= "+ uri.toString());
                }
            });
        }
    });`

我不确定如何返回Firstore上传的最终任务，因为它是在图像上传任务中完成的。我的目标是侦听uploadToFireStore（）何时完成，然后通知我的视图。任何建议，将不胜感激。谢谢！

编辑：我的结构像这样- 视图已从用户获取信息，并将其作为自定义对象传递给viewmodel。然后，视图模型调用db进行上传。我的想法是从数据库返回一个任务到viewmodel，这将返回所述任务到视图。查看是否完成检查，然后停止加载程序。这是思考这个问题的好方法吗？

Answer 1

我的工作示例。

public class SomeClass {
    private String downloadUrl;
    private final FirebaseStorage storage = FirebaseStorage.getInstance();
    private int count = 0;

    public interface Callback {
        void callingBack();
        void getReady();
    }

    public int getCount() {
        return count;
    }

    private Callback callback;

    public void registerCallBack(Callback callback) {
        this.callback = callback;
    }


    public String getImageUri () {
        return downloadUrl;
    }

    public void uploadImage (String srcPath, String fileName, Context context, int size) {
        StorageReference storageRef = storage.getReference();
        StorageReference imageRef = storageRef.child(fileName);
        try {
            InputStream inputStream = new FileInputStream(new File(srcPath));
            imageRef.putStream(inputStream)
                    .continueWithTask(task -> imageRef.getDownloadUrl())
                    .addOnCompleteListener(task -> {
                        downloadUrl = task.getResult().toString();
                        callback.callingBack();
                        this.count++;
                        if (this.count == size) {
                            callback.getReady();
                            this.count = 0;
                        }
                    });
        } catch (Exception e) {
            Toast.makeText(context, "Connection error", Toast.LENGTH_LONG).show();
        }
    }    
}

活动代码

    public void someMehtod() {

            String fileName;
            String filePath;
            int size = YOUR_SIZE;
            String[] imgUrlList = new String[size];
            for (int i = 0; i < size; i++) {
                fileName = "img_" + i + ".jpg"; // set target file name
                filePath = "/storage/emulated/0/Download/images_" + i + ".jpg"; // for example (u need get your real source file paths)
                getImageUri.registerCallBack(new GetImageUri.Callback() {
                    @Override
                    public void callingBack() {
                        imgUrlList [getImageUri.getCount()] = getImageUri.getImageUri();
                        }
                    }
    
                    @Override
                    public void getReady() {
                        // here u can use your URLs
                        for (int k = 0; k < size; k ++) {
                            Log.d(TAG, "getReady: " + imgUrlList [k]);    
                    }
                });
                getImageUri.uploadImage(filePath, fileName, this.getContext(), imgListCount);
            }
        }

Answer 2

我想出了解决问题的方法。使用回调。像这样创建一个界面

public interface Callback {
  void result(Result result);
  void url(Uri downloadUrl);
}

注意：结果是具有两个值FAILED和SUCCESS的枚举类然后在您的视图中像这样调用视图模型

ViewModel.saveoBJECT(mObject, new Callback() {
        @Override
        public void result(Result result) {
            switch (result){
                case SUCCESS:
                    mProgressbar.setVisibility(View.GONE);
                    break;
                case FAILED:
                    Log.v(TAG, "Failed");
                    Toast.makeText(getApplicationContext(), "OOPS ERROR!", Toast.LENGTH_LONG).show();
                    break;
            }
        }

        @Override
        public void url(Uri downloadUrl) { }
    });

在您的数据库中执行以下操作

  uploadImage(Uri.parse(imageString), prepend, new Callback() {
            @Override
            public void result(Result result) {}

            @Override
            public void uri(Uri downloadUrl) {
                saveObjectInDB(downloadUrl, new Callback() {
                    @Override
                    public void result(Result result) {
                        callback.result(result);
                    }

                    @Override
                    public void url(Uri downloadUrl) { }
                });
            }
        });

在上传图片功能中

 ref.putFile(file).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                @Override
                public void onSuccess(Uri uri) {
                    callback.journey(uri);
                    Log.d(TAG, "onSuccess: uri= "+ uri.toString());
                }
            });
        }
    });

并在saveObjectInDB函数中执行此操作

 db.collection(DATABASE).add(O)
        .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
            @Override
            public void onSuccess(DocumentReference documentReference) {
                Log.w(TAG, "Document upload complete");
                callback.result(Result.SUCCESS);
            }
        })
        .addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Log.w(TAG, "Error adding uploading document", e);
                callback.result(Result.FAILED);
            }
        });

上载到Firebase仓库等待上载完成，然后上载到Firebase并返回任务

2 个答案: