1　状况形式的UML类图#

状况形式的UML类图如下图所示。

2　运用状况形式完成登录状况自在切换#

首要创立笼统状况人物UserState类。

public abstract class UserState {
    protected AppContext context;

    public void setContext(AppContext context) {
        this.context = context;
    }

    public abstract void favorite();

    public abstract void comment(String comment);
}

然后创立登录状况LogInState类。

创立未登录状况UnloginState类。

public class UnLoginState extends UserState {
    @Override
    public void favorite() {
        this.switch2Login();
        this.context.getState().favorite();
    }

    @Override
    public void comment(String comment) {
        this.switch2Login();
        this.context.getState().comment(comment);
    }

    private void switch2Login() {
        System.out.println("跳转到登录页面!");
        this.context.setState(this.context.STATE_LOGIN);
    }
}

创立上下文人物AppContext类。

public class AppContext {
    public static final UserState STATE_LOGIN = new LoginInState();
    public static final UserState STATE_UNLOGIN = new UnLoginState();
    private UserState currentState = STATE_UNLOGIN;
    {
        STATE_LOGIN.setContext(this);
        STATE_UNLOGIN.setContext(this);
    }

    public void setState(UserState state) {
        this.currentState = state;
        this.currentState.setContext(this);
    }

    public UserState getState() {
        return this.currentState;
    }

    public void favorite() {
        this.currentState.favorite();
    }

    public void comment(String comment) {
        this.currentState.comment(comment);
    }
}

最终编写客户端测验代码。

public static void main(String[] args) {
        AppContext context = new AppContext();
        context.favorite();
        context.comment("谈论: 好文章，360个赞!");
}

运转成果如下图所示。

3　运用状况机完成订单状况流通操控#

状况机是状况形式的一种运用，相当于上下文人物的一个升级版。在工作流或游戏等各种体系中有很多运用，如各种工作流引擎，它几乎是状况机的子集和完成，封装状况的改动规矩。Spring也供给了一个很好的解决方案。Spring中的组件称号就叫作状况机（StateMachine）。状况机协助开发者简化状况操控的开发进程，让状况机结构愈加层次化。下面用Spring状况机模仿一个订单状况流通的进程。

3.1 增加依靠。#

<dependency>
    <groupId>org.springframework.statemachine</groupId>
    <artifactId>spring-statemachine-core</artifactId>
    <version>2.0.1.RELEASE</version>
</dependency>

3.2 创立订单实体Order类。#

public class Order {
    private int id;
    private OrderStatus status;
    public void setStatus(OrderStatus status) {
        this.status = status;
    }

    public OrderStatus getStatus() {
        return status;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getId() {
        return id;
    }

    @Override
    public String toString() {
        return "订单号：" + id + ", 订单状况：" + status;
    }
}

3.3 创立订单状况枚举类和状况转化枚举类。#

/**
 * 订单状况
 */
public enum OrderStatus {
    //待付出，待发货，待收货，订单完毕
    WAIT_PAYMENT, WAIT_DELIVER, WAIT_RECEIVE, FINISH;
}

/**
 * 订单状况改动事情
 */
public enum OrderStatusChangeEvent {
    //付出，发货，承认收货
    PAYED, DELIVERY, RECEIVED;
}

3.4 增加状况流通装备。#

/**
 * 订单状况机装备
 */
@Configuration
@EnableStateMachine(name = "orderStateMachine")
public class OrderStateMachineConfig extends StateMachineConfigurerAdapter<OrderStatus, OrderStatusChangeEvent> {
 
    /**
     * 装备状况
     * @param states
     * @throws Exception
     */
    public void configure(StateMachineStateConfigurer<OrderStatus, OrderStatusChangeEvent> 	states) throws Exception {
        states
                .withStates()
                .initial(OrderStatus.WAIT_PAYMENT)
                .states(EnumSet.allOf(OrderStatus.class));
    }
 
    /**
     * 装备状况转化事情联系
     * @param transitions
     * @throws Exception
     */
    public void configure(StateMachineTransitionConfigurer<OrderStatus, OrderStatusChangeEvent> 	transitions) throws Exception {
        transitions
                .withExternal().source(OrderStatus.WAIT_PAYMENT).target(OrderStatus.WAIT_DELIVER)
                .event(OrderStatusChangeEvent.PAYED)
                .and()
                .withExternal().source(OrderStatus.WAIT_DELIVER).target(OrderStatus.WAIT_RECEIVE)
                .event(OrderStatusChangeEvent.DELIVERY)
                .and()
                .withExternal().source(OrderStatus.WAIT_RECEIVE).target(OrderStatus.FINISH)
                .event(OrderStatusChangeEvent.RECEIVED);
    }
 
    /**
     * 耐久化装备
     * 在实际运用中，能够合作Redis等进行耐久化操作
     * @return
     */
    @Bean
    public DefaultStateMachinePersister persister(){
        return new DefaultStateMachinePersister<>(new StateMachinePersist<Object, Object, 			Order>() {
            @Override
            public void write(StateMachineContext<Object, Object> context, Order order) throws 			Exception {
                //此处并没有进行耐久化操作
            }
 
            @Override
            public StateMachineContext<Object, Object> read(Order order) throws Exception {
                //此处直接获取Order中的状况，其实并没有进行耐久化读取操作
                return new DefaultStateMachineContext(order.getStatus(), null, null, null);
            }
        });
    }
}

3.5 增加订单状况监听器。#

@Component("orderStateListener")
@WithStateMachine(name = "orderStateMachine")
public class OrderStateListenerImpl{
 
    @OnTransition(source = "WAIT_PAYMENT", target = "WAIT_DELIVER")
    public boolean payTransition(Message<OrderStatusChangeEvent> message) {
        Order order = (Order) message.getHeaders().get("order");
        order.setStatus(OrderStatus.WAIT_DELIVER);
        System.out.println("付出，状况机反应信息：" + message.getHeaders().toString());
        return true;
    }
 
    @OnTransition(source = "WAIT_DELIVER", target = "WAIT_RECEIVE")
    public boolean deliverTransition(Message<OrderStatusChangeEvent> message) {
        Order order = (Order) message.getHeaders().get("order");
        order.setStatus(OrderStatus.WAIT_RECEIVE);
        System.out.println("发货，状况机反应信息：" + message.getHeaders().toString());
        return true;
    }
 
    @OnTransition(source = "WAIT_RECEIVE", target = "FINISH")
    public boolean receiveTransition(Message<OrderStatusChangeEvent> message){
        Order order = (Order) message.getHeaders().get("order");
        order.setStatus(OrderStatus.FINISH);
        System.out.println("收货，状况机反应信息：" + message.getHeaders().toString());
        return true;
    }
}

3.6 创立IOrderService接口。#

public interface IOrderService {
    //创立新订单
    Order create();
    //建议付出
    Order pay(int id);
    //订单发货
    Order deliver(int id);
    //订单收货
    Order receive(int id);
    //获取一切订单信息
    Map<Integer, Order> getOrders();
}

3.7 在Service事务逻辑中运用。#

@Service("orderService")
public class OrderServiceImpl implements IOrderService {

    @Autowired
    private StateMachine<OrderStatus, OrderStatusChangeEvent> orderStateMachine;
 
    @Autowired
    private StateMachinePersister<OrderStatus, OrderStatusChangeEvent, Order> persister;
 
    private int id = 1;
    private Map<Integer, Order> orders = new HashMap<>();

    public Order create() {
        Order order = new Order();
        order.setStatus(OrderStatus.WAIT_PAYMENT);
        order.setId(id++);
        orders.put(order.getId(), order);
        return order;
    }

    public Order pay(int id) {
        Order order = orders.get(id);
        System.out.println("线程称号：" + Thread.currentThread().getName() + " 测验付出，订单号：" + id);
        Message message = MessageBuilder.withPayload(OrderStatusChangeEvent.PAYED).
setHeader("order", order).build();
        if (!sendEvent(message, order)) {
            System.out.println("线程称号：" + Thread.currentThread().getName() + " 付出失利, 状况反常，订单号：" + id);
        }
        return orders.get(id);
    }

    public Order deliver(int id) {
        Order order = orders.get(id);
        System.out.println("线程称号：" + Thread.currentThread().getName() + " 测验发货，订单号：" + id);
        if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.DELIVERY)
.setHeader("order", order).build(), orders.get(id))) {
            System.out.println("线程称号：" + Thread.currentThread().getName() + " 发货失利，状况反常，订单号：" + id);
        }
        return orders.get(id);
    }

    public Order receive(int id) {
        Order order = orders.get(id);
        System.out.println("线程称号：" + Thread.currentThread().getName() + " 测验收货，订单号：" + id);
        if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.RECEIVED)
.setHeader("order", order).build(), orders.get(id))) {
            System.out.println("线程称号：" + Thread.currentThread().getName() + " 收货失利，状况反常，订单号：" + id);
        }
        return orders.get(id);
    }
 

    public Map<Integer, Order> getOrders() {
        return orders;
    }
 
 
    /**
     * 发送订单状况转化事情
     *
     * @param message
     * @param order
     * @return
     */
    private synchronized boolean sendEvent(Message<OrderStatusChangeEvent> message, Order order) {
        boolean result = false;
        try {
            orderStateMachine.start();
            //测验康复状况机状况
            persister.restore(orderStateMachine, order);
            //增加推迟用于线程安全测验
            Thread.sleep(1000);
            result = orderStateMachine.sendEvent(message);
            //耐久化状况机状况
            persister.persist(orderStateMachine, order);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            orderStateMachine.stop();
        }
        return result;
    }
}

3.8 编写客户端测验代码。#

@SpringBootApplication
public class Test {
    public static void main(String[] args) {

        Thread.currentThread().setName("主线程");

        ConfigurableApplicationContext context = SpringApplication.run(Test.class,args);

        IOrderService orderService = (IOrderService)context.getBean("orderService");

        orderService.create();
        orderService.create();

        orderService.pay(1);

        new Thread("客户线程"){
            @Override
            public void run() {
                orderService.deliver(1);
                orderService.receive(1);
            }
        }.start();

        orderService.pay(2);
        orderService.deliver(2);
        orderService.receive(2);

        System.out.println("悉数订单状况：" + orderService.getOrders());

    }
}

经过这个实在的事务事例，信任小伙伴们现已对状况形式有了一个十分深入的了解。

原文链接：https://www.cnblogs.com/gupaoedu-tom/p/15560874.html