Dart example of Google Cloud Storage upload and download

gcloud_storage_example.dart

import 'dart:async';
import 'dart:io';

import 'package:gcloud/storage.dart';
import 'package:googleapis_auth/auth_io.dart' as auth;

class StorageGateway {
  final Bucket _bucket;

  StorageGateway._internal(this._bucket);

  static Future<StorageGateway> create() async {
    // Init Google Cloud Storage
    var credentials =
        auth.ServiceAccountCredentials.fromJson('service_account.json');
    var client =
        await auth.clientViaServiceAccount(credentials, Storage.SCOPES);
    var storage = Storage(client, 'project_id');
    var bucket = await storage.bucket('bucket_id');

    return StorageGateway._internal(bucket);
  }

  Future<void> download(String remotePath, String localPath) =>
      _bucket.read(remotePath).pipe(File(localPath).openWrite());

  Future<void> upload(String localPath, String remotePath) =>
      File(localPath).openRead().pipe(_bucket.write(remotePath));
}