Spring @OnApplicationEvent用法示例小结(典型用法)

// 定义事件类
public class UserRegisteredEvent extends ApplicationEvent {
    private final String username;
    public UserRegisteredEvent(Object source, String username) {
        super(source);
        this.username = username;
    }
    public String getUsername() {
        return username;
    }
}
// 发布事件
@Service
public class UserService {
    @Autowired
    private ApplicationEventPublisher eventPublisher;
    public void registerUser(String username) {
        System.out.println("用户注册：" + username);
        eventPublisher.publishEvent(new UserRegisteredEvent(this, username));
    }
}
// 监听事件
@Component
public class UserRegistrationListener {
    @OnApplicationEvent
    public void onUserRegistered(UserRegisteredEvent event) {
        System.out.println("监听到用户注册事件：" + event.getUsername());
    }
}

// 监听应用启动完成事件
@Component
public class StartupEventListener {
    @OnApplicationEvent
    public void onApplicationReady(ApplicationReadyEvent event) {
        System.out.println("应用已启动完成");
    }
}

@Component
public class AsyncEventListener {
    @OnApplicationEvent
    @Async
    public void handleUserRegistered(UserRegisteredEvent event) {
        System.out.println("【异步】收到用户注册事件：" + event.getUsername());
    }
}

@Component
public class ConditionalEventListener {
    @OnApplicationEvent(condition = "#event.username.startsWith('admin')")
    public void onAdminUserRegistered(UserRegisteredEvent event) {
        System.out.println("管理员用户注册：" + event.getUsername());
    }
}

@Component
public class MultiEventLogger {
    @OnApplicationEvent
    public void logEvent(ApplicationEvent event) {
        System.out.println("监听到事件：" + event.getClass().getSimpleName());
    }
}