轻量级状态机框架 Sateless4j 实践_stateless4j permitdynamic

状态机选型

• squirrel-foundation
• Spring statemachine
• stateless4j

关于这几个对比，文章比较多，这里就不赘述了。

这三个，我基本都有直接或间接使用过。

简单感受是：

squirrel-foundation，同事用过，功能丰富，较为轻量，上手简单。

Spring statemachine，自己调研过，和 Spring 天然集成，注解声明，功能丰富，同时上手较复杂，状态机实例不能单例使用，线程不安全。

stateless4j ，轻量、简单，轻度使用，很 nice，对代码侵入极小。GitHub - stateless4j/stateless4j: Lightweight Java State Machine

实践

质量检测任务（简称：质检任务）的状态流转图：

new 一个类，名为：QcStateMachine 质检状态机。

依据上面的状态转移图，配置状态转移。

提前准备两个枚举类：状态枚举、时间枚举。前置态-接受到事件->后置态。

    private static final StateMachineConfig<QualityStatusEnum, QualityEventEnum> CONFIG = new StateMachineConfig<>();
 
    static {
        /*
         * 最初为 INIT 状态时
         */
        CONFIG.configure(QualityStatusEnum.INIT)
                // .permitDynamic(new TriggerWithParameters1<>(QualityEventEnum.APPLY_QUALITY_TASK, QcTask.class), qcTask -> {
                //     return QualityStatusEnum.CHECKING;
                // })
                .permit(QualityEventEnum.APPLY_QUALITY_TASK, QualityStatusEnum.CHECKING)
                .permit(QualityEventEnum.SAVE_QUALITY_RESULT, QualityStatusEnum.CHECKING)
                .permit(QualityEventEnum.SUBMIT_QUALITY_RESULT, QualityStatusEnum.RECHECKING)
                .ignore(QualityEventEnum.DELETE);
 
        CONFIG.configure(QualityStatusEnum.CHECKING)
                .ignore(QualityEventEnum.SAVE_QUALITY_RESULT)
                .permit(QualityEventEnum.SUBMIT_QUALITY_RESULT, QualityStatusEnum.RECHECKING);
 
        CONFIG.configure(QualityStatusEnum.RECHECKING)
                .ignore(QualityEventEnum.SUBMIT_RECHECK_RESULT)
                .permit(QualityEventEnum.RECHECK_EXPIRE, QualityStatusEnum.RECHECKED);
 
        CONFIG.configure(QualityStatusEnum.RECHECKED)
                .permit(QualityEventEnum.AMEND, QualityStatusEnum.AMENDED)
                .permit(QualityEventEnum.AMEND_EXPIRE, QualityStatusEnum.AMENDED);
 
    }

//构建状态机实例，传入当前状态和状态转移配置
StateMachine<QualityStatusEnum, QualityEventEnum> sm = new StateMachine<>(current, CONFIG)
//判断当前状态能不能接受目标事件: 提交质检结果
if (sm.canFire(QualityEventEnum.SUBMIT_QUALITY_RESULT)) {
  // 中断
}
 
//接受事件，状态转移到下一个状态
sm.fire();
 
//更新表里的状态
QualityStatusEnum nextState = sm.getState(); //推荐这样获取下一个状态，减少硬编码
...

上面时最简单的轻量使用。

如果需要在状态转移时，伴随一些动作逻辑，可以在状态转移配置中设置。

QcStateMachine 完整代码：

import com.github.oxo42.stateless4j.StateMachine;
import com.github.oxo42.stateless4j.StateMachineConfig;
import com.sankuai.groceryrisk.common.core.exception.DialogException;
import com.sankuai.groceryrisk.risk.investigation.service.constant.enums.QualityEventEnum;
import com.sankuai.groceryrisk.risk.investigation.service.constant.enums.QualityStatusEnum;
import lombok.extern.slf4j.Slf4j;
 
/**
 * <p>
 *
 * @author L&J
 * @version 0.1
 * @since 2023/2/4 12:10
 */
@Slf4j
public class QcStateMachine {
 
    private static final StateMachineConfig<QualityStatusEnum, QualityEventEnum> CONFIG = new StateMachineConfig<>();
 
    static {
        /*
         * 最初为 INIT 状态时
         */
        CONFIG.configure(QualityStatusEnum.INIT)
                // .permitDynamic(new TriggerWithParameters1<>(QualityEventEnum.APPLY_QUALITY_TASK, QcTask.class), qcTask -> {
                //     return QualityStatusEnum.CHECKING;
                // })
                .permit(QualityEventEnum.APPLY_QUALITY_TASK, QualityStatusEnum.CHECKING)
                .permit(QualityEventEnum.SAVE_QUALITY_RESULT, QualityStatusEnum.CHECKING)
                .permit(QualityEventEnum.SUBMIT_QUALITY_RESULT, QualityStatusEnum.RECHECKING)
                .ignore(QualityEventEnum.DELETE);
 
        CONFIG.configure(QualityStatusEnum.CHECKING)
                .ignore(QualityEventEnum.SAVE_QUALITY_RESULT)
                .permit(QualityEventEnum.SUBMIT_QUALITY_RESULT, QualityStatusEnum.RECHECKING);
 
        CONFIG.configure(QualityStatusEnum.RECHECKING)
                .ignore(QualityEventEnum.SUBMIT_RECHECK_RESULT)
                .permit(QualityEventEnum.RECHECK_EXPIRE, QualityStatusEnum.RECHECKED);
 
        CONFIG.configure(QualityStatusEnum.RECHECKED)
                .permit(QualityEventEnum.AMEND, QualityStatusEnum.AMENDED)
                .permit(QualityEventEnum.AMEND_EXPIRE, QualityStatusEnum.AMENDED);
 
    }
 
    public static StateMachine<QualityStatusEnum, QualityEventEnum> of(Integer sourceState) {
        return of(QualityStatusEnum.getByValue(sourceState));
    }
 
    public static StateMachine<QualityStatusEnum, QualityEventEnum> of(QualityStatusEnum sourceState) {
        return new StateMachine<>(sourceState, CONFIG);
    }
 
    public static boolean canFire(Integer current, QualityEventEnum event) {
        return canFire(QualityStatusEnum.getByValue(current), event);
    }
 
    /**
     * 当前状态是否接受当前事件
     * @param current 当前状态, 前置态
     * @param event 事件
     */
    public static boolean canFire(QualityStatusEnum current, QualityEventEnum event) {
        StateMachine<QualityStatusEnum, QualityEventEnum> sm = new StateMachine<>(current, CONFIG);
        return sm.canFire(event);
    }
 
    public static StateMachine<QualityStatusEnum, QualityEventEnum> checkFireOrThrow(Integer current, QualityEventEnum event) {
        return checkFireOrThrow(QualityStatusEnum.getByValue(current), event);
    }
 
    public static StateMachine<QualityStatusEnum, QualityEventEnum> checkFireOrThrow(QualityStatusEnum current, QualityEventEnum event) {
        StateMachine<QualityStatusEnum, QualityEventEnum> sm = new StateMachine<>(current, CONFIG);
        if (!sm.canFire(event)) {
            throw new DialogException("当前任务状态('{}')不可'{}'", current.getLabel(), event.getLabel());
        }
        return sm;
    }