Cola状态机实战

小落的编程笔记

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分类专栏：状态机文章标签： java 状态模式

于 2025-01-24 17:27:53 首次发布

本文链接：https://blog.youkuaiyun.com/TimeZRO/article/details/145343798

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一.简介

状态机模式通常用于定义一个对象在有限状态间流转的行为，比如常见的订单中，通常有待支付，已支付，已发货，已完成，已取消，已退款等，且这些状态的转换都是提前定义好的。这样可以用状态机来定义各个状态间的流转事件和触发事件，比如从待支付到已支付需要触发支付操作，而在触发的事件里可以定义不同的操作，比如支付完成之后发放优惠券等。

二.依赖

 <dependency>
     <groupId>com.alibaba.cola</groupId>
     <artifactId>cola-component-statemachine</artifactId>
     <version>最新版本</version>
 </dependency>

三.实战

此处贴出我在项目中使用的状态机的UML图, 其中部分状态是在此项目中的特殊业务状态:

(1)定义状态枚举

状态枚举用于定义状态机会变更到的所有状态

public enum OrderState {

    INIT(1, "已创建"),
    WAITING_FOR_PAY(5, "待支付"),
    WAITING_FOR_ASSIGNED(9,"待分配"),
    ASSIGNED_PART(10,"部分分配"),
    WAITING_FOR_DELIVER(13, "待发货"),
    WAITING_FOR_LOCK(17, "待锁单"),
    COMPLETE(21, "已完成"),
    CANCEL(25, "已取消"),
    WAITING_FOR_REFUND(29, "待退款"),
    REFUNDED(33, "已退款"),
    ;


    private String msg;
    private int code;

    OrderState(int code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public int getCode() {
        return this.code;
    }

    public String getMsg() {
        return this.msg;
    }

    public static OrderState getInstance(int code) {

        for (OrderState value : values()) {
            if (value.code == code) {
                return value;
            }
        }
        return null;
    }
}

(2)定义事件枚举

事件枚举是状态机会触发的所有事件

public enum OrderEvent {

	CREATE_ORDER(1, "创建订单"),
	PAY(2, "支付"),
	CANCEL_ORDER(3, "取消订单"),
	ASSIGNED(4, "分配号码"),
	PART_ASSIGNED(5, "部分分配"),
	CANCEL_ASSIGNED(6, "取消分配"),
	PART_CANCEL_ASSIGNED(7, "部分取消分配"),
	DELIVERY(8, "发货"),
	LOCK(9, "锁单"),
	APPLY_FOR_REFUND(10, "申请退款"),
	REFUND(11, "退款"),
	;


	private String msg;

	private int code;

	OrderEvent(int code, String msg) {
		this.code = code;
		this.msg = msg;
	}

}

(3)状态机ID

状态机ID是每个状态机的唯一ID, 此处用枚举保存, 也可以用常量

public enum OrderStateMachineIdEnum {

	CARD_ORDER("ORDER_STATE_MACHINE", "订单状态机");

	private String machineId;

	private String name;

	OrderStateMachineIdEnum(String machineId, String name) {
		this.machineId = machineId;
		this.name = name;
	}

	public String getMachineId() {
		return this.machineId;
	}

	public String getName() {
		return this.name;
	}
}


StateMachine<OrderState, OrderEvent, OrderContext> orderStateMachine = StateMachineFactory.get(OrderStateMachineIdEnum.CARD_ORDER.name());

// 此方法用于获取状态机的UML图 生成的是字符串 需要使用工具转换成上面的UML图(直接找个在线工具即可)
System.out.println(orderStateMachine.generatePlantUML());

(4)context

context 是用于在状态机中传输数据的上下文

@Data
@AllArgsConstructor
@NoArgsConstructor
public class OrderContext {

	// 订单编号
	private String orderNo;

	// 其他参数 此处使用超类 Object 可以接收任意类型, 使用时根据类型转换
	private Object context;

}

(5)conditon

condition是用于定义从一个状态扭转到另一个状态的必须条件, 只有返回值为true会执行后续的action

@Slf4j
@Component
public class OrderCheckCancelCondition implements Condition<OrderContext> {


	@Override
	public boolean isSatisfied(OrderContext orderContext) {

		log.info("订单:{},取消前校验完成", orderContext.getOrderNo());
		return true;
	}

}

(6)action

action是用于定义从一个状态扭转到另一个状态之后触发的动作

@Slf4j
@Component
@AllArgsConstructor
public class OrderCreateAction implements Action<OrderState, OrderEvent, OrderContext> {

	private final IOrderService orderService;


	@Override
	public void execute(OrderState from, OrderState to, OrderEvent orderEvent, OrderContext orderContext) {
		log.info("创建订单,订单编号:{}", orderContext.getOrderNo());
		CreateOrderDTO createOrderDTO = (CreateOrderDTO) orderContext.getContext();

		orderService.doCreateOrder(to, orderContext.getOrderNo(), createOrderDTO);

	}

}

(7)状态机配置

cola状态机可以定义内部状态流转,外部状态流转,批量状态流转

externalTransition用于定义外部状态流转, from表示当前状态, to表示扭转后的状态,when表示需要满足的条件, perform表示需要执行的动作(action)

internalTransition用于定于内部状态流转, within表示状态, 内部状态流转不用定义to

externalTransitions用于定义批量状态流转, 也就是从多个状态可以抵达同一个状态,比如: 订单在已发货,已锁单等状态都可以进行退款操作, fromAmong表示多个from的状态

@Component
@AllArgsConstructor
public class OrderStateMachine {

	private final OrderActionHelper orderActionHelper;
	private final OrderConditionHelper orderConditionHelper;


	@PostConstruct
	public StateMachine<OrderState, OrderEvent, OrderContext> createStateMachine() {
		// 创建状态机
		StateMachineBuilder<OrderState, OrderEvent, OrderContext> builder = StateMachineBuilderFactory.create();

		// 外部状态流转 从init到待支付 需要触发创建订单操作
		builder.externalTransition()
			.from(OrderState.INIT)
			.to(OrderState.WAITING_FOR_PAY)
			.on(OrderEvent.CREATE_ORDER)
			.when(orderConditionHelper.getOrderCheckCreateCondition())
			.perform(orderActionHelper.getOrderCreateAction());

		// 外部状态流转 从待支付到已取消 需要触发取消订单操作
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_PAY)
			.to(OrderState.CANCEL)
			.on(OrderEvent.CANCEL_ORDER)
			.when(orderConditionHelper.getOrderCheckCancelCondition())
			.perform(orderActionHelper.getOrderCancelAction());

		// 外部状态流转 从待支付到待分配 需要触发支付操作
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_PAY)
			.to(OrderState.WAITING_FOR_ASSIGNED)
			.on(OrderEvent.PAY)
			.when(orderConditionHelper.getOrderCheckPayCondition())
			.perform(orderActionHelper.getOrderPayAction());

		// 外部状态流转 从待分配到部分分配 需要触发部分分配操作
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_ASSIGNED)
			.to(OrderState.ASSIGNED_PART)
			.on(OrderEvent.PART_ASSIGNED)
			.when(orderConditionHelper.getOrderCheckPartAssignCondition())
			.perform(orderActionHelper.getOrderPartAssignAction());

		// 内部状态流转 部分分配 需要触发部分分配操作
		builder.internalTransition().within(OrderState.ASSIGNED_PART)
			.on(OrderEvent.PART_ASSIGNED)
			.when(orderConditionHelper.getOrderCheckPartAssignCondition())
			.perform(orderActionHelper.getOrderPartAssignAction());

		// 外部状态流转 从待分配,部分分配到待发货 需要触发分配操作
		builder.externalTransitions()
			.fromAmong(OrderState.ASSIGNED_PART, OrderState.WAITING_FOR_ASSIGNED)
			.to(OrderState.WAITING_FOR_DELIVER)
			.on(OrderEvent.ASSIGNED)
			.when(orderConditionHelper.getOrderCheckAssignCondition())
			.perform(orderActionHelper.getOrderAssignAction());

		// 外部状态流转 从待发货到部分分配 需要触发部分取消分配事件
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_DELIVER)
			.to(OrderState.ASSIGNED_PART)
			.on(OrderEvent.PART_CANCEL_ASSIGNED)
			.when(orderConditionHelper.getOrderCheckPartCancelAssignedCondition())
			.perform(orderActionHelper.getOrderPartCancelAssignAction());

		// 外部状态流转 从待发货,部分分配到待分配 需要触发取消分配事件
		builder.externalTransitions()
			.fromAmong(OrderState.WAITING_FOR_DELIVER, OrderState.ASSIGNED_PART)
			.to(OrderState.WAITING_FOR_ASSIGNED)
			.on(OrderEvent.CANCEL_ASSIGNED)
			.when(orderConditionHelper.getOrderCheckCancelAssignCondition())
			.perform(orderActionHelper.getOrderCancelAssignAction());

		// 内部状态流转 部分分配 需要触发部分取消分配操作
		builder.internalTransition().within(OrderState.ASSIGNED_PART)
			.on(OrderEvent.PART_CANCEL_ASSIGNED)
			.when(orderConditionHelper.getOrderCheckPartCancelAssignedCondition())
			.perform(orderActionHelper.getOrderPartCancelAssignAction());

		// 外部状态流转 从待发货到待锁单 需要触发发货事件
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_DELIVER)
			.to(OrderState.WAITING_FOR_LOCK)
			.on(OrderEvent.DELIVERY)
			.when(orderConditionHelper.getOrderCheckDeliveryCondition())
			.perform(orderActionHelper.getOrderDeliveryAction());

		// 外部状态流转 从待锁单到已完成 需要触发锁单事件
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_LOCK)
			.to(OrderState.COMPLETE)
			.on(OrderEvent.LOCK)
			.when(orderConditionHelper.getOrderCheckLockCondition())
			.perform(orderActionHelper.getOrderLockAction());

		// 外部状态流转 从待分配,部分分配,待发货,待锁单,已完成到待退款 需要触发申请退款事件
		builder.externalTransitions()
			.fromAmong(OrderState.WAITING_FOR_ASSIGNED, OrderState.ASSIGNED_PART, OrderState.WAITING_FOR_DELIVER,
				OrderState.WAITING_FOR_LOCK, OrderState.COMPLETE)
			.to(OrderState.WAITING_FOR_REFUND)
			.on(OrderEvent.APPLY_FOR_REFUND)
			.when(orderConditionHelper.getOrderCheckApplyForRefundedCondition())
			.perform(orderActionHelper.getOrderApplyForRefundedAction());

		// 外部状态流转 从待退款到已退款 需要触发退款事件
		builder.externalTransition()
			.from(OrderState.WAITING_FOR_REFUND)
			.to(OrderState.REFUNDED)
			.on(OrderEvent.REFUND)
			.when(orderConditionHelper.getOrderCheckRefundedCondition())
			.perform(orderActionHelper.getOrderRefundedAction());

		return builder.build(OrderStateMachineIdEnum.CARD_ORDER.getMachineId());
	}

}

(9) helper工具类

定义下面两个工具类的目的在于, 在状态机的配置类中就不需要分别注入依赖, 只需要注入这两个Bean就可以, 不想使用这种方式也可以在状态机配置类中分别注入


@Component
@AllArgsConstructor
public class OrderActionHelper {


	private final OrderCreateAction orderCreateAction;
	private final OrderCancelAction orderCancelAction;
	private final OrderPayAction orderPayAction;
	private final OrderPartAssignAction orderPartAssignAction;
	private final OrderAssignAction orderAssignAction;
	private final OrderPartCancelAssignAction orderPartCancelAssignAction;
	private final OrderCancelAssignAction orderCancelAssignAction;
	private final OrderDeliveryAction orderDeliveryAction;
	private final OrderLockAction orderLockAction;
	private final OrderApplyForRefundedAction orderApplyForRefundedAction;
	private final OrderRefundedAction orderRefundedAction;

	public Action<OrderState, OrderEvent, OrderContext> getOrderCreateAction() {
		return orderCreateAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderCancelAction() {
		return orderCancelAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderPayAction() {
		return orderPayAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderPartAssignAction() {
		return orderPartAssignAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderAssignAction() {
		return orderAssignAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderPartCancelAssignAction() {
		return orderPartCancelAssignAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderCancelAssignAction() {
		return orderCancelAssignAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderDeliveryAction() {
		return orderDeliveryAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderLockAction() {
		return orderLockAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderApplyForRefundedAction() {
		return orderApplyForRefundedAction;
	}

	public Action<OrderState, OrderEvent, OrderContext> getOrderRefundedAction() {
		return orderRefundedAction;
	}
}


@Component
@AllArgsConstructor
public class OrderConditionHelper {

	private final OrderCheckCreateCondition orderCheckCreateCondition;
	private final OrderCheckCancelCondition orderCheckCancelCondition;
	private final OrderCheckPayCondition orderCheckPayCondition;
	private final OrderCheckPartAssignCondition orderCheckPartAssignCondition;
	private final OrderCheckAssignCondition orderCheckAssignCondition;
	private final OrderCheckPartCancelAssignedCondition orderCheckPartCancelAssignedCondition;
	private final OrderCheckCancelAssignCondition orderCheckCancelAssignCondition;
	private final OrderCheckDeliveryCondition orderCheckDeliveryCondition;
	private final OrderCheckLockCondition orderCheckLockCondition;
	private final OrderCheckApplyForRefundedCondition orderCheckApplyForRefundedCondition;
	private final OrderCheckRefundedCondition orderCheckRefundedCondition;

	public Condition<OrderContext> getOrderCheckCreateCondition() {
		return orderCheckCreateCondition;
	}

	public Condition<OrderContext> getOrderCheckCancelCondition() {
		return orderCheckCancelCondition;
	}

	public Condition<OrderContext> getOrderCheckPayCondition() {
		return orderCheckPayCondition;
	}

	public Condition<OrderContext> getOrderCheckPartAssignCondition() {
		return orderCheckPartAssignCondition;
	}

	public Condition<OrderContext> getOrderCheckAssignCondition() {
		return orderCheckAssignCondition;
	}

	public Condition<OrderContext> getOrderCheckPartCancelAssignedCondition() {
		return orderCheckPartCancelAssignedCondition;
	}

	public Condition<OrderContext> getOrderCheckCancelAssignCondition() {
		return orderCheckCancelAssignCondition;
	}

	public Condition<OrderContext> getOrderCheckDeliveryCondition() {
		return orderCheckDeliveryCondition;
	}

	public Condition<OrderContext> getOrderCheckLockCondition() {
		return orderCheckLockCondition;
	}

	public Condition<OrderContext> getOrderCheckApplyForRefundedCondition() {
		return orderCheckApplyForRefundedCondition;
	}

	public Condition<OrderContext> getOrderCheckRefundedCondition() {
		return orderCheckRefundedCondition;
	}
}

(10)示例触发事件

通过fireEvent()方法可以触发事件, 如果需要对操作进行加锁, 可以直接对此方法加锁

	public void cancelOrder(String orderNo) {

		StateMachine<OrderState, OrderEvent, OrderContext> orderStateMachine = StateMachineFactory.get(OrderStateMachineIdEnum.CARD_ORDER.getMachineId());

		// 此处使用分布式锁处理
		orderUtil.handlerWithLock(orderNo, () -> {

			OrderRecordEntity order = getByOrderNo(orderNo);
			checkOrderExists(order);

			OrderContext orderContext = new OrderContext();
			orderContext.setOrderNo(orderNo);
			orderContext.setOrder(order);

			OrderState orderState = orderStateMachine.fireEvent(OrderState.getInstance(order.getStatus()), OrderEvent.CANCEL_ORDER, orderContext);

			if (OrderState.CANCEL.getCode() != orderState.getCode()) {
				throw new ServiceException("此状态无法取消订单!");
			}
		});


	}

	/**
	 * 阻塞式获取锁处理订单
	 * @param orderNo
	 * @param runnable
	 */
	public void handlerWithLock(String orderNo, Runnable runnable) {

		RLock orderLock = redissonClient.getLock(orderNo);

		orderLock.lock();

		try {

			runnable.run();

		} finally {

			orderLock.unlock();

		}

	}