@SpringBootApplication
@EnableAsync // 僅異步場景需要
public class EcommerceApplication {
    public static void main(String[] args) {
        SpringApplication.run(EcommerceApplication.class, args);
    }
}

// 自定義事件類
public class OrderPlacedEvent extends ApplicationEvent {
    // 事件攜帶的業(yè)務(wù)數(shù)據(jù)
    private final Order order;
    // 構(gòu)造函數(shù)：source=事件源（如OrderService），order=業(yè)務(wù)數(shù)據(jù)
    public OrderPlacedEvent(Object source, Order order) {
        super(source);
        this.order = order;
    }
    // 獲取業(yè)務(wù)數(shù)據(jù)的getter
    public Order getOrder() {
        return order;
    }
}
// 配套的業(yè)務(wù)模型（示例）
public class Order {
    private String orderId;
    private String userId;
    private double amount;
    // 省略構(gòu)造器、getter/setter
}

@Service
public class OrderService {
    // 注入事件發(fā)布器
    @Autowired
    private ApplicationEventPublisher eventPublisher;
    // 核心業(yè)務(wù)方法：創(chuàng)建訂單后發(fā)布事件
    public void placeOrder(Order order) {
        // 1. 執(zhí)行核心業(yè)務(wù)邏輯（如保存訂單到數(shù)據(jù)庫）
        order.setOrderId("ORDER-" + System.currentTimeMillis());
        System.out.println("訂單創(chuàng)建成功：" + order.getOrderId());
        // 2. 發(fā)布自定義事件（觸發(fā)時(shí)機(jī)由業(yè)務(wù)決定）
        eventPublisher.publishEvent(new OrderPlacedEvent(this, order));
    }
}

@Component
public class InventoryListener {
    // 方式1：參數(shù)類型隱式綁定OrderPlacedEvent
    @Async // 可選：異步執(zhí)行，需配合@EnableAsync
    @EventListener
    public void handleOrderEvent(OrderPlacedEvent event) {
        Order order = event.getOrder();
        // 處理事件邏輯（如扣減庫存）
        System.out.println("【庫存監(jiān)聽器】處理訂單：" + order.getOrderId() + "，扣減庫存");
    }
}
// 方式2：顯式指定監(jiān)聽的事件類型（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();
            // 處理事件邏輯（如發(fā)送通知）
            System.out.println("【通知監(jiān)聽器】處理訂單：" + order.getOrderId() + "，發(fā)送下單通知");
        }
    }
}

@Component
public class AnalyticsListener implements ApplicationListener<OrderPlacedEvent> {
    @Override
    public void onApplicationEvent(OrderPlacedEvent event) {
        Order order = event.getOrder();
        // 處理事件邏輯（如統(tǒng)計(jì)銷售數(shù)據(jù)）
        System.out.println("【分析監(jiān)聽器】處理訂單：" + order.getOrderId() + "，統(tǒng)計(jì)銷售數(shù)據(jù)");
    }
}

@Configuration
public class AsyncConfig {
    @Bean(name = "asyncTaskExecutor")
    public Executor asyncTaskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(5); // 核心線程數(shù)
        executor.setMaxPoolSize(10); // 最大線程數(shù)
        executor.setQueueCapacity(20); // 任務(wù)隊(duì)列
        executor.setThreadNamePrefix("Async-"); // 線程名前綴
        executor.initialize();
        return executor;
    }
}
// 監(jiān)聽器指定自定義線程池
@Async("asyncTaskExecutor")
@EventListener
public void handleOrderEvent(OrderPlacedEvent event) {
    // 業(yè)務(wù)邏輯...
}

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