如何使用spring boot在Google Firebase FCM上推送通知？

<dependency>
    <groupId>com.google.firebase</groupId>
    <artifactId>firebase-admin</artifactId>
    <version>8.0.0</version>
</dependency>

import com.google.auth.oauth2.GoogleCredentials;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import org.springframework.context.annotation.Configuration;

import javax.annotation.PostConstruct;
import java.io.FileInputStream;
import java.io.IOException;

@Configuration
public class FirebaseConfig {

    @PostConstruct
    public void initialize() throws IOException {
        FileInputStream serviceAccount = new FileInputStream("path/to/serviceAccountKey.json");

        FirebaseOptions options = new FirebaseOptions.Builder()
                .setCredentials(GoogleCredentials.fromStream(serviceAccount))
                .build();

        FirebaseApp.initializeApp(options);
    }
}

import com.google.firebase.messaging.FirebaseMessaging;
import com.google.firebase.messaging.Message;
import com.google.firebase.messaging.Notification;
import org.springframework.stereotype.Service;

@Service
public class NotificationService {

    public void sendNotification(String title, String body, String token) {
        Message message = Message.builder()
                .setNotification(new Notification(title, body))
                .setToken(token)
                .build();

        try {
            FirebaseMessaging.getInstance().send(message);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class NotificationController {

    @Autowired
    private NotificationService notificationService;

    @PostMapping("/send-notification")
    public void sendNotification(@RequestBody NotificationRequest request) {
        notificationService.sendNotification(request.getTitle(), request.getBody(), request.getToken());
    }
}