状态模式升级-利用spring状态机轻松实现状态模式

Spring State Machine（状态机）入门 - spring 中文网

• 引入状态机maven依赖2.7.X的boot版本要对应3.2.1的状态机

<dependency>
    <groupId>org.springframework.statemachine</groupId>
    <artifactId>spring-statemachine-core</artifactId>
    <version>3.2.1</version>
</dependency>

• 定义状态、行为

/**
 * @description: 模拟订单类
 */
@Data
public class Order {
    private Long orderId;
    private OrderStatusEnum orderStatus;
}

/**
 * @description: 订单状态
 */
public enum OrderStatusEnum {
    // 待支付
    WAIT_PAYMENT,
    // 待发货
    WAIT_DELIVER,
    // 待收货
    WAIT_RECEIVE,
    // 完成
    FINISH;
}

/**
 * @description:订单状态转换行为
 */
public enum OrderStatusChangeEventEnum {
    //支付
    PAYED,
    //发货
    DELIVERY,
    //收货
    RECEIVED;
}

- 关键： 配置 转换关系

/**
 * @description: 订单状态机
 */
@Configuration
@EnableStateMachine
public class OrderStatusMachineConfig extends StateMachineConfigurerAdapter<OrderStatusEnum, OrderStatusChangeEventEnum> {

    /**
     * 配置状态
     */
    @Override
    public void configure(StateMachineStateConfigurer<OrderStatusEnum, OrderStatusChangeEventEnum> states) throws Exception {
        states.withStates()
                .initial(OrderStatusEnum.WAIT_PAYMENT)
                .end(OrderStatusEnum.FINISH)
                .states(EnumSet.allOf(OrderStatusEnum.class));
    }

    /**
     * 配置状态转换事件关系
     */
    @Override
    public void configure(StateMachineTransitionConfigurer<OrderStatusEnum, OrderStatusChangeEventEnum> transitions) throws Exception {
        transitions.withExternal().source(OrderStatusEnum.WAIT_PAYMENT).target(OrderStatusEnum.WAIT_DELIVER)
                .event(OrderStatusChangeEventEnum.PAYED)
                .and()
                .withExternal().source(OrderStatusEnum.WAIT_DELIVER).target(OrderStatusEnum.WAIT_RECEIVE)
                .event(OrderStatusChangeEventEnum.DELIVERY)
                .and()
                .withExternal().source(OrderStatusEnum.WAIT_RECEIVE).target(OrderStatusEnum.FINISH)
                .event(OrderStatusChangeEventEnum.RECEIVED);
    }
}

- 监听状态变更事件，完成状态转换。

/**
 * @description: 状态监听
 */
@Component
@WithStateMachine
@Transactional
public class OrderStatusListener {
    @OnTransition(source = "WAIT_PAYMENT", target = "WAIT_DELIVER")
    public boolean payTransition(Message message) {
        Order order = (Order) message.getHeaders().get("order");
        order.setOrderStatus(OrderStatusEnum.WAIT_DELIVER);
        System.out.println("支付，状态机反馈信息：" + message.getHeaders().toString());
        return true;
    }

    @OnTransition(source = "WAIT_DELIVER", target = "WAIT_RECEIVE")
    public boolean deliverTransition(Message message) {
        Order order = (Order) message.getHeaders().get("order");
        order.setOrderStatus(OrderStatusEnum.WAIT_RECEIVE);
        System.out.println("发货，状态机反馈信息：" + message.getHeaders().toString());
        return true;
    }

    @OnTransition(source = "WAIT_RECEIVE", target = "FINISH")
    public boolean receiveTransition(Message message) {
        Order order = (Order) message.getHeaders().get("order");
        order.setOrderStatus(OrderStatusEnum.FINISH);
        System.out.println("收货，状态机反馈信息：" + message.getHeaders().toString());
        return true;
    }

}

/**
 * @description: 订单服务
 */
@Service
public class OrderServiceImpl implements OrderService {

    @Resource
    private StateMachine<OrderStatusEnum, OrderStatusChangeEventEnum> orderStateMachine;

    private long id = 1L;

    private Map<Long, Order> orders = new ConcurrentHashMap();

    @Override
    public Order create() {
        Order order = new Order();
        order.setOrderStatus(OrderStatusEnum.WAIT_PAYMENT);
        order.setOrderId(id++);
        orders.put(order.getOrderId(), order);
        System.out.println("订单创建成功:" + order.toString());
        return order;
    }

    @Override
    public Order pay(long id) {
        Order order = orders.get(id);
        System.out.println("尝试支付，订单号：" + id);
        Message message = MessageBuilder.withPayload(OrderStatusChangeEventEnum.PAYED).
                setHeader("order", order).build();
        if (!sendEvent(message)) {
            System.out.println(" 支付失败, 状态异常，订单号：" + id);
        }
        return orders.get(id);
    }

    @Override
    public Order deliver(long id) {
        Order order = orders.get(id);
        System.out.println(" 尝试发货，订单号：" + id);
        if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEventEnum.DELIVERY)
                .setHeader("order", order).build())) {
            System.out.println(" 发货失败，状态异常，订单号：" + id);
        }
        return orders.get(id);
    }

    @Override
    public Order receive(long id) {
        Order order = orders.get(id);
        System.out.println(" 尝试收货，订单号：" + id);
        if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEventEnum.RECEIVED)
                .setHeader("order", order).build())) {
            System.out.println(" 收货失败，状态异常，订单号：" + id);
        }
        return orders.get(id);
    }


    @Override
    public Map<Long, Order> getOrders() {
        return orders;
    }

    /**
     * 发送状态转换事件
     * @param message
     * @return
     */
    private synchronized boolean sendEvent(Message<OrderStatusChangeEventEnum> message) {
        boolean result = false;
        try {
            orderStateMachine.start();
            result = orderStateMachine.sendEvent(message);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (Objects.nonNull(message)) {
                Order order = (Order) message.getHeaders().get("order");
                if (Objects.nonNull(order) && Objects.equals(order.getOrderStatus(), OrderStatusEnum.FINISH)) {
                    orderStateMachine.stop();
                }
            }
        }
        return result;
    }
}