问未从firebase存储中检索到下载Url

EN

uploadTask
            .addOnSuccessListener(AdminDisplayProductActivity.this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
                @Override
                public void onSuccess(final UploadTask.TaskSnapshot taskSnapshot) {


                    new Handler().postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            mProgressBar.setProgress(0);
                            downloadUrl = taskSnapshot.getMetadata().getReference().getDownloadUrl().toString();
                            AddProduct(downloadUrl);

                            Toast.makeText(AdminDisplayProductActivity.this, "Uploaded !" + downloadUrl, Toast.LENGTH_SHORT).show();
                        }
                    }, 500);

                    Toast.makeText(AdminDisplayProductActivity.this, "File Uploaded"
                            , Toast.LENGTH_SHORT).show();

                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Toast.makeText(AdminDisplayProductActivity.this, "Upload Fail !", Toast.LENGTH_SHORT).show();
                }
            })
            .addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
                @Override
                public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
                    double progress = (100.0 * taskSnapshot.getBytesTransferred() / taskSnapshot.getTotalByteCount());
                    mProgressBar.setProgress((int) progress);
                }
            });