如何在Flutter中使用Firebase Admin SDK？

dependencies:
  firebase_admin: ^x.x.x

import 'package:firebase_admin/firebase_admin.dart';

var credential = FirebaseAdmin.instance.certFromPath('path/to/serviceAccountKey.json');
FirebaseAdmin.instance.initializeApp(credential, '<your-database-url>');

var database = FirebaseAdmin.instance.database();
var ref = database.ref('path/to/data');
ref.once('value').then((snapshot) {
  var data = snapshot.val();
  // 处理数据
});

ref.set({'key': 'value'}).then((_) {
  // 写入成功
});

var messaging = FirebaseAdmin.instance.messaging();
var message = Message(
  notification: Notification(
    title: 'Notification Title',
    body: 'Notification Body',
  ),
  token: '<device-token>',
);
messaging.send(message).then((response) {
  // 发送成功
});