Spring 自定义事件监听器实现步骤详解

@SpringBootApplication
@EnableAsync // 仅异步场景需要
public class EcommerceApplication {
    public static void main(String[] args) {
        SpringApplication.run(EcommerceApplication.class, args);
    }
}

// 自定义事件类
public class OrderPlacedEvent extends ApplicationEvent {
    // 事件携带的业务数据
    private final Order order;
    // 构造函数：source=事件源（如OrderService），order=业务数据
    public OrderPlacedEvent(Object source, Order order) {
        super(source);
        this.order = order;
    }
    // 获取业务数据的getter
    public Order getOrder() {
        return order;
    }
}
// 配套的业务模型（示例）
public class Order {
    private String orderId;
    private String userId;
    private double amount;
    // 省略构造器、getter/setter
}

@Service
public class OrderService {
    // 注入事件发布器
    @Autowired
    private ApplicationEventPublisher eventPublisher;
    // 核心业务方法：创建订单后发布事件
    public void placeOrder(Order order) {
        // 1. 执行核心业务逻辑（如保存订单到数据库）
        order.setOrderId("ORDER-" + System.currentTimeMillis());
        System.out.println("订单创建成功：" + order.getOrderId());
        // 2. 发布自定义事件（触发时机由业务决定）
        eventPublisher.publishEvent(new OrderPlacedEvent(this, order));
    }
}

@Component
public class InventoryListener {
    // 方式1：参数类型隐式绑定OrderPlacedEvent
    @Async // 可选：异步执行，需配合@EnableAsync
    @EventListener
    public void handleOrderEvent(OrderPlacedEvent event) {
        Order order = event.getOrder();
        // 处理事件逻辑（如扣减库存）
        System.out.println("【库存监听器】处理订单：" + order.getOrderId() + "，扣减库存");
    }
}
// 方式2：显式指定监听的事件类型（支持多事件）
@Component
public class NotificationListener {
    @EventListener(classes = {OrderPlacedEvent.class})
    public void handleMultiEvent(Object event) {
        if (event instanceof OrderPlacedEvent) {
            Order order = ((OrderPlacedEvent) event).getOrder();
            // 处理事件逻辑（如发送通知）
            System.out.println("【通知监听器】处理订单：" + order.getOrderId() + "，发送下单通知");
        }
    }
}

@Component
public class AnalyticsListener implements ApplicationListener<OrderPlacedEvent> {
    @Override
    public void onApplicationEvent(OrderPlacedEvent event) {
        Order order = event.getOrder();
        // 处理事件逻辑（如统计销售数据）
        System.out.println("【分析监听器】处理订单：" + order.getOrderId() + "，统计销售数据");
    }
}

@Configuration
public class AsyncConfig {
    @Bean(name = "asyncTaskExecutor")
    public Executor asyncTaskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(5); // 核心线程数
        executor.setMaxPoolSize(10); // 最大线程数
        executor.setQueueCapacity(20); // 任务队列
        executor.setThreadNamePrefix("Async-"); // 线程名前缀
        executor.initialize();
        return executor;
    }
}
// 监听器指定自定义线程池
@Async("asyncTaskExecutor")
@EventListener
public void handleOrderEvent(OrderPlacedEvent event) {
    // 业务逻辑...
}

@RestController
@RequestMapping("/api/orders")
public class OrderController {
    @Autowired
    private OrderService orderService;
    @PostMapping
    public String createOrder(@RequestBody Order order) {
        orderService.placeOrder(order);
        return "订单提交成功，订单号：" + order.getOrderId();
    }
}