一、状态机
有限状态机是一种用来进行对象行为建模的工具，其作用主要是描述对象在它的生命周期内所经历的状态序列，以及如何响应来自外界的各种事件。在电商场景（订单、物流、售后）、社交（IM消息投递）、分布式集群管理（分布式计算平台任务编排）等场景都有大规模的使用。
状态机的要素：
状态机可归纳为4个要素，现态、条件、动作、次态。“现态”和“条件”是因，“动作”和“次态”是果。
1 现态：指当前所处的状态
2 条件：又称“事件”，当一个条件被满足，将会触发一个动作，或者执行一次状态的迁移
3 动作：条件满足后执行的动作。动作执行完毕后，可以迁移到新的状态，也可以仍旧保持原状态。动作不是必须的，当条件满足后，也可以不执行任何动作，直接迁移到新的状态。
4 次态：条件满足后要迁往的新状态。“次态”是相对于“现态”而言的，“次态”一旦被激活，就转换成“现态”。
状态机动作类型：
进入动作：在进入状态时进行
退出动作：在退出状态时进行
输入动作：依赖于当前状态和输入条件进行
转移动作：在进行特定转移时进行
二、spring statemachine
spring statemachine是使用 Spring框架下的状态机概念创建的一种应用程序开发框架。它使得状态机结构层次化，简化了配置状态机的过程。
例子一：简单订单流程
使用过程：
1 引入依赖
<!--spring statemachine-->
<dependency>
<groupId>org.springframework.statemachine</groupId>
<artifactId>spring-statemachine-core</artifactId>
<version>2.0.1.RELEASE</version>
</dependency>
2 创建订单状态枚举类和状态转换枚举类
/**
* 订单状态
*/
public enum OrderStatus {
// 待支付，待发货，待收货，订单结束
WAIT_PAYMENT, WAIT_DELIVER, WAIT_RECEIVE, FINISH;
}
/**
* 订单状态改变事件
*/
public enum OrderStatusChangeEvent {
// 支付，发货，确认收货
PAYED, DELIVERY, RECEIVED;
}
3 添加配置
/**
* 订单状态机配置
*/
@Configuration
@EnableStateMachine(name = "orderStateMachine")
public class OrderStateMachineConfig extends StateMachineConfigurerAdapter<OrderStatus, OrderStatusChangeEvent> {
/**
* 配置状态
* @param states
* @throws Exception
*/
@Override
public void configure(StateMachineStateConfigurer<OrderStatus, OrderStatusChangeEvent> states) throws Exception {
states
.withStates()
.initial(OrderStatus.WAIT_PAYMENT)
.states(EnumSet.allOf(OrderStatus.class));
}
/**
* 配置状态转换事件关系
* @param transitions
* @throws Exception
*/
@Override
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);
}
/**
* 持久化配置
* 实际使用中，可以配合redis等，进行持久化操作
* @return
*/
@Bean
public StateMachinePersister<OrderStatus, OrderStatusChangeEvent, Order> persister(){
return new DefaultStateMachinePersister<>(new StateMachinePersist<OrderStatus, OrderStatusChangeEvent, Order>() {
@Override
public void write(StateMachineContext<OrderStatus, OrderStatusChangeEvent> context, Order order) throws Exception {
//此处并没有进行持久化操作
}
@Override
public StateMachineContext<OrderStatus, OrderStatusChangeEvent> read(Order order) throws Exception {
//此处直接获取order中的状态，其实并没有进行持久化读取操作
return new DefaultStateMachineContext<>(order.getStatus(), null, null, null);
}
});
}
}
4 添加订单状态监听器
@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("支付 headers=" + 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 headers=" + 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 headers=" + message.getHeaders().toString());
return true;
}
}5 service中使用
@Service("orderService")
public class OrderServiceImpl implements OrderService {
@Autowired
private OrderMapper orderMapper;
@Autowired
private StateMachine<OrderStatus, OrderStatusChangeEvent> orderStateMachine;
@Autowired
private StateMachinePersister<OrderStatus, OrderStatusChangeEvent, Order> persister;
private int id = 1;
private Map<Integer, Order> orders = new HashMap<>();
@Override
public Order creat() {
Order order = new Order();
order.setStatus(OrderStatus.WAIT_PAYMENT);
order.setId(id++);
orders.put(order.getId(), order);
return order;
}
@Override
public Order pay(int id) {
Order order = orders.get(id);
System.out.println("threadName=" + Thread.currentThread().getName() + " 尝试支付 id=" + id);
Message message = MessageBuilder.withPayload(OrderStatusChangeEvent.PAYED).setHeader("order", order).build();
if (!sendEvent(message, order)) {
System.out.println("threadName=" + Thread.currentThread().getName() + " 支付失败, 状态异常 id=" + id);
}
return orders.get(id);
}
@Override
public Order deliver(int id) {
Order order = orders.get(id);
System.out.println("threadName=" + Thread.currentThread().getName() + " 尝试发货 id=" + id);
if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.DELIVERY).setHeader("order", order).build(), orders.get(id))) {
System.out.println("threadName=" + Thread.currentThread().getName() + " 发货失败，状态异常 id=" + id);
}
return orders.get(id);
}
@Override
public Order receive(int id) {
Order order = orders.get(id);
System.out.println("threadName=" + Thread.currentThread().getName() + " 尝试收货 id=" + id);
if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.RECEIVED).setHeader("order", order).build(), orders.get(id))) {
System.out.println("threadName=" + Thread.currentThread().getName() + " 收货失败，状态异常 id=" + id);
}
return orders.get(id);
}
@Override
public Map<Integer, Order> getOrders() {
return orders;
}
/**
* 发送订单状态转换事件
*
* @param message
* @param order
* @return
*/
private synchronized boolean sendEvent(Message<OrderStatusChangeEvent> message, Order order) {
boolean result = false;
try {
orderStateMachine.start();
//尝试恢复状态机状态
persister.restore(orderStateMachine, order);
//添加延迟用于线程安全测试
Thread.sleep(1000);
result = orderStateMachine.sendEvent(message);
//持久化状态机状态
persister.persist(orderStateMachine, order);
} catch (Exception e) {
e.printStackTrace();
} finally {
orderStateMachine.stop();
}
return result;
}
}6 测试
@Slf4j
@RunWith(SpringRunner.class)
@SpringBootTest
public class OrderServiceImplTest {
@Autowired
private OrderService orderService;
@Test
public void testMultThread(){
orderService.creat();
orderService.creat();
orderService.pay(1);
new Thread(()->{
orderService.deliver(1);
orderService.receive(1);
}).start();
orderService.pay(2);
orderService.deliver(2);
orderService.receive(2);
System.out.println(orderService.getOrders());
}
}
例子二：状态机工厂
有些时候，一个状态机不够用，因为我们可能要处理多个订单。这个时候就要用到了状态机工厂。
1 配置修改
/**
* 订单状态机配置
*/
@Configuration
//@EnableStateMachine(name = "orderStateMachine")
@EnableStateMachineFactory(name = "orderStateMachineFactory")
public class OrderStateMachineConfig extends EnumStateMachineConfigurerAdapter<OrderStatus, OrderStatusChangeEvent> {
/**订单状态机ID*/
public static final String orderStateMachineId = "orderStateMachineId";
/**
* 配置状态
* @param states
* @throws Exception
*/
@Override
public void configure(StateMachineStateConfigurer<OrderStatus, OrderStatusChangeEvent> states) throws Exception {
states
.withStates()
.initial(OrderStatus.WAIT_PAYMENT)
.states(EnumSet.allOf(OrderStatus.class));
}
/**
* 配置状态转换事件关系
* @param transitions
* @throws Exception
*/
@Override
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);
}
/**
* 持久化配置
* 实际使用中，可以配合redis等，进行持久化操作
* @return
*/
@Bean
public StateMachinePersister<OrderStatus, OrderStatusChangeEvent, Order> persister(){
return new DefaultStateMachinePersister<>(new StateMachinePersist<OrderStatus, OrderStatusChangeEvent, Order>() {
@Override
public void write(StateMachineContext<OrderStatus, OrderStatusChangeEvent> context, Order order) throws Exception {
//此处并没有进行持久化操作
order.setStatus(context.getState());
}
@Override
public StateMachineContext<OrderStatus, OrderStatusChangeEvent> read(Order order) throws Exception {
//此处直接获取order中的状态，其实并没有进行持久化读取操作
StateMachineContext<OrderStatus, OrderStatusChangeEvent> result =new DefaultStateMachineContext<>(order.getStatus(), null, null, null, null, orderStateMachineId);
return result;
}
});
}
}
2 service中使用
@Service("orderService")
public class OrderServiceImpl implements OrderService {
@Autowired
private OrderMapper orderMapper;
// @Autowired
// private StateMachine<OrderStatus, OrderStatusChangeEvent> orderStateMachine;
public static final String stateMachineId = "orderStateMachine";
@Autowired
private StateMachineFactory<OrderStatus, OrderStatusChangeEvent> orderStateMachineFactory;
@Autowired
private StateMachinePersister<OrderStatus, OrderStatusChangeEvent, Order> persister;
private int id = 1;
private Map<Integer, Order> orders = new HashMap<>();
@Override
public Order creat() {
Order order = new Order();
order.setStatus(OrderStatus.WAIT_PAYMENT);
order.setId(id++);
orders.put(order.getId(), order);
return order;
}
@Override
public Order pay(int id) {
Order order = orders.get(id);
System.out.println(" 等待支付 -> 等待发货 id=" + id + " threadName=" + Thread.currentThread().getName());
Message message = MessageBuilder.withPayload(OrderStatusChangeEvent.PAYED).setHeader("order", order).build();
if (!sendEvent(message, order)) {
System.out.println(" 等待支付 -> 等待发货 失败, 状态异常 id=" + id + " threadName=" + Thread.currentThread().getName());
} else {
System.out.println(" 等待支付 -> 等待发货 成功 id=" + id + " threadName=" + Thread.currentThread().getName());
}
return orders.get(id);
}
@Override
public Order deliver(int id) {
Order order = orders.get(id);
System.out.println(" 等待发货 -> 等待收货 id=" + id + " threadName=" + Thread.currentThread().getName());
if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.DELIVERY).setHeader("order", order).build(), orders.get(id))) {
System.out.println(" 等待发货 -> 等待收货 失败，状态异常 id=" + id + " threadName=" + Thread.currentThread().getName());
} else {
System.out.println(" 等待发货 -> 等待收货 成功 id=" + id + " threadName=" + Thread.currentThread().getName());
}
return orders.get(id);
}
@Override
public Order receive(int id) {
Order order = orders.get(id);
System.out.println(" 等待收货 -> 完成 收货 id=" + id + " threadName=" + Thread.currentThread().getName());
if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.RECEIVED).setHeader("order", order).build(), orders.get(id))) {
System.out.println(" 等待收货 -> 完成 失败，状态异常 id=" + id + " threadName=" + Thread.currentThread().getName());
} else {
System.out.println(" 等待收货 -> 完成 成功 id=" + id + " threadName=" + Thread.currentThread().getName());
}
return orders.get(id);
}
@Override
public Map<Integer, Order> getOrders() {
return orders;
}
/**
* 发送订单状态转换事件
*
* @param message
* @param order
* @return
*/
private boolean sendEvent(Message<OrderStatusChangeEvent> message, Order order) {
synchronized (String.valueOf(order.getId()).intern()) {
boolean result = false;
StateMachine<OrderStatus, OrderStatusChangeEvent> orderStateMachine = orderStateMachineFactory.getStateMachine(stateMachineId);
System.out.println("id=" + order.getId() + " 状态机 orderStateMachine" + orderStateMachine);
try {
orderStateMachine.start();
//尝试恢复状态机状态
persister.restore(orderStateMachine, order);
System.out.println("id=" + order.getId() + " 状态机 orderStateMachine id=" + orderStateMachine.getId());
//添加延迟用于线程安全测试
Thread.sleep(1000);
result = orderStateMachine.sendEvent(message);
//持久化状态机状态
persister.persist(orderStateMachine, order);
} catch (Exception e) {
e.printStackTrace();
} finally {
orderStateMachine.stop();
}
return result;
}
}
}3 listener中配置id
@Component("orderStateListener")
@WithStateMachine(id = OrderStateMachineConfig.orderStateMachineId)
public class OrderStateListenerImpl {
@OnTransition(source = "WAIT_PAYMENT", target = "WAIT_DELIVER")
public boolean payTransition(Message<OrderStatusChangeEvent> message) {
System.out.println("----------------------------");
Order order = (Order) message.getHeaders().get("order");
order.setStatus(OrderStatus.WAIT_DELIVER);
System.out.println("支付 headers=" + message.getHeaders().toString() + " event=" + message.getPayload());
System.out.println("----------------------------");
return true;
}
@OnTransition(source = "WAIT_DELIVER", target = "WAIT_RECEIVE")
public boolean deliverTransition(Message<OrderStatusChangeEvent> message) {
System.out.println("----------------------------");
Order order = (Order) message.getHeaders().get("order");
order.setStatus(OrderStatus.WAIT_RECEIVE);
System.out.println("发货 headers=" + message.getHeaders().toString() + " event=" + message.getPayload());
System.out.println("----------------------------");
return true;
}
@OnTransition(source = "WAIT_RECEIVE", target = "FINISH")
public boolean receiveTransition(Message<OrderStatusChangeEvent> message) {
System.out.println("----------------------------");
Order order = (Order) message.getHeaders().get("order");
order.setStatus(OrderStatus.FINISH);
System.out.println("收货 headers=" + message.getHeaders().toString() + " event=" + message.getPayload());
System.out.println("----------------------------");
return true;
}
}
