Spring状态机的介绍与使用

<!--        状态机-->
        <dependency>
            <groupId>org.springframework.statemachine</groupId>
            <artifactId>spring-statemachine-starter</artifactId>
            <version>2.2.0.RELEASE</version>
        </dependency>
<!-- Spring State Machine Redis -->
        <dependency>
         <groupId>org.springframework.statemachine</groupId>
        <artifactId>spring-statemachine-redis</artifactId>
    </dependency>                

public enum OrderState {
    UNPAID,                 // 待支付
    WAITING_FOR_RECEIVE,    // 待收货
    DONE                    // 结束
}

public enum OrderEvents {
    PAY,        // 支付
    RECEIVE     // 收货
}

@Configuration
@EnableStateMachine(name = "StateMachineConfig")
public class StateMachineConfig extends EnumStateMachineConfigurerAdapter<TestState, TestEvents> {

    private Logger logger = LoggerFactory.getLogger(getClass());
    //定义初始状态
    @Override
    public void configure(StateMachineStateConfigurer<TestState, TestEvents> states)
            throws Exception {
        states
            .withStates()
                .initial(TestState.UNPAID)
                .states(EnumSet.allOf(TestState.class));
    }
    //状态转换过程 触发什么事件就转换为什么状态
    @Override
    public void configure(StateMachineTransitionConfigurer<TestState, TestEvents> transitions)
            throws Exception {
        transitions
            .withExternal()
                .source(TestState.UNPAID).target(TestState.WAITING_FOR_RECEIVE)
                .event(TestEvents.PAY)
                .and()
            .withExternal()
                .source(TestState.WAITING_FOR_RECEIVE).target(TestState.DONE)
                .event(TestEvents.RECEIVE);
    }
}

@Component
@WithStateMachine(name = "StateMachineConfig")
public class EventListener {

    private Logger logger = LoggerFactory.getLogger(getClass());

    @OnTransition(target = "UNPAID")
    public boolean create(Message<Order> order) {
　　　　 // 创建订单逻辑
        logger.info("订单创建，待支付");
        return true;
    }

    @OnTransition(source = "UNPAID", target = "WAITING_FOR_RECEIVE")
    public boolean pay(Message<Order> order) {
        // 支付逻辑 从redis根据order 来进行处理
        logger.info("用户完成支付，待收货");
        return true;
    }

    @OnTransition(source = "WAITING_FOR_RECEIVE", target = "DONE")
    public boolean receive(Message<Order> order) {
　　　　　//从redis中根据传入的order 来查询当前订单 并业务处理
        logger.info("用户已收货，订单完成");
        return true;
    }

}

@SpringBootApplication
public class DemoApplication implements CommandLineRunner {
    public DemoApplication(StateMachine<TestState, TestEvents> stateMachine) {
        this.stateMachine = stateMachine;
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
    private final StateMachine<TestState, TestEvents> stateMachine;

    @Override
    public void run(String... args) throws Exception {
        Order order=new Order("测试",0);
        // 使用 MessageBuilder 创建消息并设置负载和头信息
        Message message = MessageBuilder
                .withPayload(TestEvents.PAY)
                .setHeader("order", order)
                .build();
        // 发送消息给状态机
        stateMachine.start();
        stateMachine.sendEvent(message);
    }
}