如何从 Firebase 存储获取 URL getDownloadURL

Question

我正在尝试获取指向我们 Firebase 存储桶中文件的“长期持久下载链接”。我已将其权限更改为

service firebase.storage {
  match /b/project-xxx.appspot.com/o {
    match /{allPaths=**} {
      allow read, write;
    }
  }
}

我的 javacode 看起来像这样：

 private String niceLink (String date){
    String link;
    // Points to the root reference
    StorageReference storageRef = FirebaseStorage.getInstance().getReference();
    StorageReference dateRef = storageRef.child("/" + date+ ".csv");
    link = dateRef.getDownloadUrl().toString();
    return link;
}

当我运行它时，我得到的 uri 链接看起来像 com.google.android.gms.tasks.zzh@xxx

问题 1。 我可以从中获取类似于以下内容的下载链接： https ://firebasestorage.googleapis.com/v0/b/project-xxxx.appspot.com/o/20-5-2016.csv?alt=media&token= b5d45a7f-3ab7-4f9b-b661-3a2187adxxxx

当试图获取上面的链接时，我在返回之前更改了最后一行，如下所示：

 private String niceLink (String date){
    String link;
    // Points to the root reference
    StorageReference storageRef = FirebaseStorage.getInstance().getReference();
    StorageReference dateRef = storageRef.child("/" + date+ ".csv");
    link = dateRef.getDownloadUrl().getResult().toString();
    return link;
}

但是这样做时我收到 403 错误，并且应用程序崩溃了。 consol 告诉我这是 bc 用户未登录 /auth。 “请先登录再索取令牌”

问题 2。 我该如何解决这个问题？

原文由 Jonathan Fager 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

请参阅 文档以获取下载 URL 。

当您调用 getDownloadUrl() 时，调用是异步的，您必须订阅成功回调才能获得结果：

 // Calls the server to securely obtain an unguessable download Url
private void getUrlAsync (String date){
    // Points to the root reference
    StorageReference storageRef = FirebaseStorage.getInstance().getReference();
    StorageReference dateRef = storageRef.child("/" + date+ ".csv");
    dateRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>()
    {
        @Override
        public void onSuccess(Uri downloadUrl)
        {
           //do something with downloadurl
        }
    });
}

这将返回一个公共的不可猜测的下载 url。如果你刚刚上传了一个文件，这个公共 url 将在上传成功的回调中（你不需要在上传后调用另一个异步方法）。

但是，如果您只需要 String 引用的表示形式，您只需调用 .toString()

 // Returns a Uri of the form gs://bucket/path that can be used
// in future calls to getReferenceFromUrl to perform additional
// actions
private String niceRefLink (String date){
    // Points to the root reference
    StorageReference storageRef = FirebaseStorage.getInstance().getReference();
    StorageReference dateRef = storageRef.child("/" + date+ ".csv");
    return dateRef.toString();
}

原文由 Benjamin Wulfe 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 2

//Firebase 存储 - 易于处理上传和下载。

 @Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable final Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode == RC_SIGN_IN){
        if(resultCode == RESULT_OK){
            Toast.makeText(this,"Signed in!", LENGTH_SHORT).show();
        } else if(resultCode == RESULT_CANCELED){
            Toast.makeText(this,"Signed in canceled!", LENGTH_SHORT).show();
            finish();
        }
    } else if(requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK){

        // HERE I CALLED THAT METHOD
        uploadPhotoInFirebase(data);

    }
}

private void uploadPhotoInFirebase(@Nullable Intent data) {
    Uri selectedImageUri = data.getData();

    // Get a reference to store file at chat_photos/<FILENAME>
    final StorageReference photoRef = mChatPhotoStorageReference
                    .child(selectedImageUri
                    .getLastPathSegment());

    // Upload file to Firebase Storage
    photoRef.putFile(selectedImageUri)
            .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                @Override
                public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

                    // Download file From Firebase Storage
                    photoRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                        @Override
                        public void onSuccess(Uri downloadPhotoUrl) {
                            //Now play with downloadPhotoUrl
                            //Store data into Firebase Realtime Database
                            FriendlyMessage friendlyMessage = new FriendlyMessage
                                    (null, mUsername, downloadPhotoUrl.toString());
                            mDatabaseReference.push().setValue(friendlyMessage);
                        }
                    });
                }
            });
}

原文由 Subhojit Halder 发布，翻译遵循 CC BY-SA 4.0 许可协议