spring 状态机使用

业务中经常会遇到状态变更的场景

比如在外卖订单配送场景中，常有这样的业务：

骑手接单动作，会触发配送状态从 待结单 ->等待配送

骑手配送动作，会触发配送状态从 配送中->配送完成

针对如上的场景我们可以使用状态机来处理

spring 提供了状态机的使用，官方文档地址：https://spring.io/projects/spring-statemachine#learn

 

现在来做个简单介绍如何使用

 

一、添加依赖

目前使用的版本是 2.4.0

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.statemachine</groupId>
            <artifactId>spring-statemachine-starter</artifactId>
            <version>${spring.statemachine.version}</version>
        </dependency>

 

二、需要定义自己的业务场景的动作和状态枚举值

 

动作枚举

import lombok.AllArgsConstructor;
import lombok.Getter;

@Getter
@AllArgsConstructor
public enum EventEnum {
    DELIVERY_CONFIRM(1,"骑手接单"),
    DELIVERY_START(2,"开始配送");
    private int value;
    private String desc;

}

 

状态枚举

import lombok.AllArgsConstructor;
import lombok.Getter;

@AllArgsConstructor
@Getter
public enum StateEnum {
    WAIT_DELIVER_RECEIVE(1,"等待骑手接单"),
    WAIT_START_DELIVERY(2,"等待骑手配送"),
    DELIVERY_END(3,"配送完成");

    private int value;
    private String desc;

}

 

三、添加配置

import com.example.demo.enums.EventEnum;
import com.example.demo.enums.StateEnum;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.statemachine.config.EnableStateMachine;
import org.springframework.statemachine.config.EnumStateMachineConfigurerAdapter;
import org.springframework.statemachine.config.builders.StateMachineConfigurationConfigurer;
import org.springframework.statemachine.config.builders.StateMachineStateConfigurer;
import org.springframework.statemachine.config.builders.StateMachineTransitionConfigurer;
import org.springframework.statemachine.listener.StateMachineListener;
import org.springframework.statemachine.listener.StateMachineListenerAdapter;
import org.springframework.statemachine.state.State;

import java.util.EnumSet;

@Configuration
@EnableStateMachine
public class StateMachineConfig extends EnumStateMachineConfigurerAdapter<StateEnum, EventEnum> {


    /**
     * 配置信息
     * @param config
     * @throws Exception
     */
    @Override
    public void configure(StateMachineConfigurationConfigurer<StateEnum, EventEnum> config) throws Exception {
        config.withConfiguration()
                .autoStartup(true)
                .listener(listener());
    }


    @Override
    public void configure(StateMachineStateConfigurer<StateEnum, EventEnum> states) throws Exception {
        states.withStates()
                .initial(StateEnum.WAIT_DELIVER_RECEIVE) //初始化状态是等待骑手接单
                .states(EnumSet.allOf(StateEnum.class));
    }


    /**
     * 状态流转
     * @param transitions
     * @throws Exception
     */
    @Override
    public void configure(StateMachineTransitionConfigurer<StateEnum, EventEnum> transitions) throws Exception {
        transitions.withExternal()
                .source(StateEnum.WAIT_DELIVER_RECEIVE).target(StateEnum.WAIT_START_DELIVERY).event(EventEnum.DELIVERY_CONFIRM) // 骑手接单动作触发 等待骑手接单状态 到 等待骑手配送
                .and().withExternal()
                .source(StateEnum.WAIT_START_DELIVERY).target(StateEnum.DELIVERY_END).event(EventEnum.DELIVERY_START);// 骑手配送动作触发 等待骑手配送状态 到 是配送完成
    }

    /**
     * 监听器
     * @return
     */
    @Bean
    public StateMachineListener<StateEnum, EventEnum> listener() {
        return new StateMachineListenerAdapter<StateEnum,EventEnum>(){
            @Override
            public void stateChanged(State<StateEnum, EventEnum> from, State<StateEnum, EventEnum> to) {
                if(null != from && null != to){
                    System.out.println("当前状态："+from.getId().getDesc() +"-->变更到："+to.getId().getDesc());
                }
            }
        };
    }
}

 

 

测试

import com.example.demo.enums.EventEnum;
import com.example.demo.enums.StateEnum;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.statemachine.StateMachine;
import org.springframework.stereotype.Service;

@Service
public class DoStateMachine implements CommandLineRunner {

    @Autowired
    private StateMachine<StateEnum, EventEnum> stateMachine;
    @Override
    public void run(String... args) throws Exception {
        stateMachine.start();
        stateMachine.sendEvent(EventEnum.DELIVERY_CONFIRM);
        stateMachine.sendEvent(EventEnum.DELIVERY_START);
    }
}

 

输出内容如下：

当前状态：等待骑手接单-->变更到：等待骑手配送

当前状态：等待骑手配送-->变更到：配送完成