一、状态机
状态机是状态模式的一种应用,相当于上下文角色的一个升级版。在工作流或游戏等各种系统中有大量使用,如各种工作流引擎,它几乎是状态机的子集和实现,封装状态的变化规则。状态机可以帮助开发者简化状态控制的开发过程,让状态机结构更加层次化。
二、状态机要素
把状态机的要素分为4个要素,即: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:是指当前所处状态;
(2)条件:又称为“事件”。当条件被满足时,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,直接迁移到新状态。
(4)次态:条件满足后要迁移往的新状态。“次态”是相对于“现态”而言的,“次态”一旦被激活,就转变成新的“现态”了。
三、状态机状态举例
以电商平台的订单状态为例,订单状态的可能有待支付、待发货、待收货、已完成、取消等。每一种状态都和变化前的状态以及执行的操作有关。
状态机图为:
四、代码步骤
Spring 提供了一个很好的解决方案,Spring Statemachine(状态机)是应用程序开发人员在 Spring 应用程序中使用状态机概念的框架。
1.添加依赖
<dependency>
<groupId>org.springframework.statemachine</groupId>
<artifactId>spring-statemachine-core</artifactId>
<version>2.0.2.RELEASE</version>
</dependency>
2.创建订单实体类
package com.sky.statemachinedemo.entity;
import lombok.Data;
/**
* 订单实体类
*/
@Data
public class Order {
private Integer id;
private Integer status;
}
3.创建订单状态枚举类
package com.sky.statemachinedemo.constants;
/**
* 订单状态枚举
*/
public enum OrderStatusEnum {
/**
* 待付款
*/
WAIT_PAYMENT(0),
/**
* 待发货
*/
WAIT_DELIVER(1),
/**
* 待收货
*/
WAIT_RECEIVE(2),
/**
* 已完成
*/
FINISH(3),
/**
* 取消
*/
CANCEL(4),
;
/**
* 订单状态
*/
public final int value;
OrderStatusEnum(int value) {
this.value = value;
}
public static Object getByValue(Integer status) {
for(OrderStatusEnum OrderStatusEnum:OrderStatusEnum.values()){
if(OrderStatusEnum.value==status){
return OrderStatusEnum;
}
}
return null;
}
}
4.创建状态转换枚举类(事件event)
package com.sky.statemachinedemo.constants;
/**
* 状态转换枚举类(事件)
*/
public enum OrderStatusChangeEvent {
// 支付,发货,确认收货
PAYED, DELIVERY, RECEIVED,CANCEL;
}
5.添加状态流配置
package com.sky.statemachinedemo.config;
import com.sky.statemachinedemo.constants.OrderStatusChangeEvent;
import com.sky.statemachinedemo.constants.OrderStatusEnum;
import com.sky.statemachinedemo.entity.Order;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.statemachine.StateMachineContext;
import org.springframework.statemachine.StateMachinePersist;
import org.springframework.statemachine.config.EnableStateMachine;
import org.springframework.statemachine.config.EnumStateMachineConfigurerAdapter;
import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
import org.springframework.statemachine.persist.DefaultStateMachinePersister;
import org.springframework.statemachine.support.DefaultStateMachineContext;
import java.util.EnumSet;
/**
* 订单状态机配置
*/
@Slf4j
@Configuration
@EnableStateMachine(name = "OrderStateMachine")
public class OrderStateMachineConfig extends EnumStateMachineConfigurerAdapter<OrderStatusEnum, OrderStatusChangeEvent> {
/**
* 配置状态
*
* @param states
* @throws Exception
*/
public void configure(StateMachineStateConfigurer<OrderStatusEnum, OrderStatusChangeEvent> states) throws Exception {
states
.withStates()
.initial(OrderStatusEnum.WAIT_PAYMENT)
.states(EnumSet.allOf(OrderStatusEnum.class));
}
/**
* 配置状态转换事件关系
*
* @param transitions
* @throws Exception
*/
public void configure(StateMachineTransitionConfigurer<OrderStatusEnum, OrderStatusChangeEvent> transitions) throws Exception {
transitions
.withExternal().source(OrderStatusEnum.WAIT_PAYMENT).target(OrderStatusEnum.WAIT_DELIVER).event(OrderStatusChangeEvent.PAYED)
.and()
.withExternal().source(OrderStatusEnum.WAIT_PAYMENT).target(OrderStatusEnum.CANCEL).event(OrderStatusChangeEvent.CANCEL)
.and()
.withExternal().source(OrderStatusEnum.WAIT_DELIVER).target(OrderStatusEnum.WAIT_RECEIVE).event(OrderStatusChangeEvent.DELIVERY)
.and()
.withExternal().source(OrderStatusEnum.WAIT_RECEIVE).target(OrderStatusEnum.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 DefaultStateMachinePersister persister() {
return new DefaultStateMachinePersister<>(new StateMachinePersist<OrderStatusEnum, OrderStatusChangeEvent, Order>() {
@Override
public void write(StateMachineContext<OrderStatusEnum, OrderStatusChangeEvent> context, Order Order) throws Exception {
//此处并没有进行持久化操作
//此处可调用更新状态流转接口(如:更新时间)状态不需要在此进行调用
}
@Override
public StateMachineContext<OrderStatusEnum, 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
//实际生产中我们会查询出订单信息,根据订单状态获取状态机状态
return new DefaultStateMachineContext(OrderStatusEnum.getByValue(Order.getStatus()), null, null, null);
}
});
}
}
6.添加订单状态监听器
package com.sky.statemachinedemo.listener;
import com.sky.statemachinedemo.constants.OrderStatusChangeEvent;
import com.sky.statemachinedemo.constants.OrderStatusEnum;
import com.sky.statemachinedemo.entity.Order;
import org.springframework.messaging.Message;
import org.springframework.statemachine.annotation.OnTransition;
import org.springframework.statemachine.annotation.WithStateMachine;
import org.springframework.stereotype.Component;
/**
* 订单状态监听器
*/
@Component("OrderStateListener")
@WithStateMachine(name = "OrderStateMachine")
public class OrderStateListener {
@OnTransition(source = "WAIT_PAYMENT", target = "WAIT_DELIVER")
public boolean payTransition(Message<OrderStatusChangeEvent> message) {
Order Order = (Order) message.getHeaders().get("order");
Order.setStatus(OrderStatusEnum.WAIT_DELIVER.value);
System.out.println("支付,状态机反馈信息:" + message.getHeaders().toString());
return true;
}
@OnTransition(source = "WAIT_PAYMENT", target = "CANCEL")
public boolean cancelTransition(Message<OrderStatusChangeEvent> message) {
Order Order = (Order) message.getHeaders().get("order");
Order.setStatus(OrderStatusEnum.CANCEL.value);
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<OrderStatusChangeEvent> message) {
Order Order = (Order) message.getHeaders().get("order");
Order.setStatus(OrderStatusEnum.WAIT_RECEIVE.value);
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<OrderStatusChangeEvent> message) {
Order Order = (Order) message.getHeaders().get("order");
Order.setStatus(OrderStatusEnum.FINISH.value);
System.out.println("收货,状态机反馈信息:" + message.getHeaders().toString());
return true;
}
}
7.创建OrderService接口
package com.sky.statemachinedemo.service;
import com.sky.statemachinedemo.entity.Order;
import java.util.Map;
public interface OrderService {
//创建订单
Order create();
//发起支付
Order pay(Integer id);
//发起支付
Order cancel(Integer id);
//订单发货
Order deliver(Integer id);
//订单收货
Order receive(Integer id);
//获取所有订单信息
//模拟数据存储的订单信息,生产中用数据库存储
Map<Integer, Order> getOrders();
}
8.在 Service 业务逻辑中应用
package com.sky.statemachinedemo.service;
import com.sky.statemachinedemo.constants.OrderStatusChangeEvent;
import com.sky.statemachinedemo.constants.OrderStatusEnum;
import com.sky.statemachinedemo.entity.Order;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.statemachine.StateMachine;
import org.springframework.statemachine.persist.StateMachinePersister;
import org.springframework.stereotype.Service;
import java.util.HashMap;
import java.util.Map;
@Service
public class OrderServiceImpl implements OrderService{
@Autowired
private StateMachine<OrderStatusEnum, OrderStatusChangeEvent> orderStateMachine;
@Autowired
private StateMachinePersister<OrderStatusEnum, OrderStatusChangeEvent, Order> persister;
private int id = 1;
private Map<Integer, Order> orders = new HashMap<>();
@Override
public Order create() {
Order order = new Order();
order.setStatus(OrderStatusEnum.WAIT_PAYMENT.value);
order.setId(id++);
orders.put(order.getId(), order);
return order;
}
@Override
public Order pay(Integer id) {
Order order = orders.get(id);
System.out.println("线程名称:" + Thread.currentThread().getName() + " 尝试支付,订单号:" + id);
Message message = MessageBuilder.withPayload(OrderStatusChangeEvent.PAYED).setHeader("order", order).build();
if (!sendEvent(message, order)) {
System.out.println("线程名称:" + Thread.currentThread().getName() + " 支付失败, 状态异常,订单号:" + id);
}
return orders.get(id);
}
@Override
public Order cancel(Integer id) {
Order order = orders.get(id);
System.out.println("线程名称:" + Thread.currentThread().getName() + " 尝试取消,订单号:" + id);
Message message = MessageBuilder.withPayload(OrderStatusChangeEvent.CANCEL).setHeader("order", order).build();
if (!sendEvent(message, order)) {
System.out.println("线程名称:" + Thread.currentThread().getName() + " 取消失败, 状态异常,订单号:" + id);
}
return orders.get(id);
}
@Override
public Order deliver(Integer id) {
Order order = orders.get(id);
System.out.println("线程名称:" + Thread.currentThread().getName() + " 尝试发货,订单号:" + id);
if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.DELIVERY).setHeader("order", order).build(), orders.get(id))) {
System.out.println("线程名称:" + Thread.currentThread().getName() + " 发货失败,状态异常,订单号:" + id);
}
return orders.get(id);
}
@Override
public Order receive(Integer id) {
Order order = orders.get(id);
System.out.println("线程名称:" + Thread.currentThread().getName() + " 尝试收货,订单号:" + id);
if (!sendEvent(MessageBuilder.withPayload(OrderStatusChangeEvent.RECEIVED).setHeader("order", order).build(), orders.get(id))) {
System.out.println("线程名称:" + Thread.currentThread().getName() + " 收货失败,状态异常,订单号:" + 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;
}
}
9.编写单元测试代码
package com.sky.statemachinedemo.service;
import com.sky.statemachinedemo.StateMachineDemoApplication;
import junit.framework.TestCase;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest(classes = StateMachineDemoApplication.class,
webEnvironment = SpringBootTest.WebEnvironment.NONE)
public class OrderServiceTest extends TestCase {
@Autowired
OrderService orderService;
@Test
public void stateTest(){
orderService.create();
orderService.pay(1);
orderService.deliver(1);
orderService.receive(1);
orderService.cancel(1);
}
}
10.也可以用controller测试,更方便
package com.sky.statemachinedemo.controller;
import com.sky.statemachinedemo.entity.Order;
import com.sky.statemachinedemo.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/order")
public class OrderController {
@Autowired
OrderService orderService;
@RequestMapping("/create")
public Order create(){
return orderService.create();
}
@RequestMapping("/cancel")
public Order cancel(Integer orderId){
return orderService.cancel(orderId);
}
@RequestMapping("/pay")
public Order pay(Integer orderId){
return orderService.pay(orderId);
}
@RequestMapping("/deliver")
public Order deliver(Integer orderId){
return orderService.deliver(orderId);
}
@RequestMapping("/receive")
public Order receive(Integer orderId){
return orderService.receive(orderId);
}
}