▲原来的状态(if-else版本)

▲改造后的状态(cola-statemachine版本)

StateMachineBuilder<ProcessStatusEnum, NodeTypeEnum, Context> builder = StateMachineBuilderFactory.create();
        builder.internalTransition().within(ProcessStatusEnum.INIT).on(NodeTypeEnum.HEAD).when(alwaysTrue()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.INIT).to(END).on(NodeTypeEnum.HEAD).when(checkNextNodeIfEndComponet()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_YUNYIN).to(ProcessStatusEnum.SUBMIT_APPLY_PASS).on(NodeTypeEnum.SUBMIT_APPLY_COMPONET).when(checkIfPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_YUNYIN).to(ProcessStatusEnum.SUBMIT_APPLY_NOT_PASS).on(NodeTypeEnum.SUBMIT_APPLY_COMPONET).when(checkIfNotPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_FK).to(ProcessStatusEnum.FK_PASS).on(NodeTypeEnum.FK_COMPONET).when(checkIfPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_FK).to(ProcessStatusEnum.FK_AUDIT_NOT_PASS).on(NodeTypeEnum.FK_COMPONET).when(checkIfNotPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_FK).to(ProcessStatusEnum.FK_REFUSE).on(NodeTypeEnum.FK_COMPONET).when(checkIfRefuse()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_CW).to(ProcessStatusEnum.CW_PASS).on(NodeTypeEnum.CW_COMPONET).when(checkIfPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_CW).to(ProcessStatusEnum.CW_NOT_PASS).on(NodeTypeEnum.CW_COMPONET).when(checkIfNotPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_CW).to(ProcessStatusEnum.CW_REFUSE).on(NodeTypeEnum.CW_COMPONET).when(checkIfRefuse()).perform(doNextProcessStatus());
        builder.externalTransition().from(ProcessStatusEnum.SOURCE_AUDIT_COMPLETE).to(ProcessStatusEnum.AUDIT_TERMINATE).on(NodeTypeEnum.AUDIT_TERMINATE).when(alwaysTrue()).perform(doNextProcessStatus());
        builder.externalTransition().from(SOURCE_OP_CHANGE_LICENSE).to(ProcessStatusEnum.UPDATE_LICENSE_SUCCESS).on(NodeTypeEnum.CHANGE_LICENSE_COMPONET).when(checkIfPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(SOURCE_OP_CHANGE_LICENSE).to(ProcessStatusEnum.UPDATE_LICENSE_FAILURE).on(NodeTypeEnum.CHANGE_LICENSE_COMPONET).when(checkIfNotPass()).perform(doNextProcessStatus());
        builder.externalTransition().from(SOURCE_END).to(END).on(NodeTypeEnum.TAIL).when(checkCurrentNodeIfEndComponet()).perform(doNextProcessStatus());
        return builder.build("processStatusMachine");

▲第一步：项目中引入Maven依赖

<dependency> 
   <groupId>com.alibaba.cola</groupId>
   <artifactId>cola-component-statemachine</artifactId> 
   <version>4.3.1</version> 
</dependency>

▲第二步：初始化状态机

@Configuration
public class StateMachineRegist {
    private final String STATE_MACHINE_ID="stateMachineId";
    /**
     * 构建状态机实例
     */
    @Bean
    public StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine() {

        StateMachineBuilder<ApplyStatusEnum, Event, LeaveContext> stateMachineBuilder = StateMachineBuilderFactory.create();
        //员工请假触发事件
        //源状态和目标状态一致，我们可以用内部流转表示
        stateMachineBuilder.internalTransition().within(ApplyStatusEnum.LEAVE_SUBMIT).on(Event.EMPLOYEE_SUBMIT).perform(doAction());
        //部门主管审批触发事件（依赖上一个源状态：LEAVE_SUBMIT）
        stateMachineBuilder.externalTransition().from(ApplyStatusEnum.LEAVE_SUBMIT).to(ApplyStatusEnum.LEADE_AUDIT_PASS).on(Event.DIRECTLEADER_AUDIT).when(checkIfPass()).perform(doAction());
        stateMachineBuilder.externalTransition().from(ApplyStatusEnum.LEAVE_SUBMIT).to(ApplyStatusEnum.LEADE_AUDIT_REFUSE).on(Event.DIRECTLEADER_AUDIT).when(checkIfNotPass()).perform(doAction());
        //hr事件触发(依赖上一个源状态:LEADE_AUDIT_PASS)
        stateMachineBuilder.externalTransition().from(ApplyStatusEnum.LEADE_AUDIT_PASS).to(ApplyStatusEnum.HR_PASS).on(Event.HR_AUDIT).when(checkIfPass()).perform(doAction());
        stateMachineBuilder.externalTransition().from(ApplyStatusEnum.LEADE_AUDIT_PASS).to(ApplyStatusEnum.HR_REFUSE).on(Event.HR_AUDIT).when(checkIfNotPass()).perform(doAction());

        return stateMachineBuilder.build(STATE_MACHINE_ID);

    }

}

LEAVE_SUBMIT、LEADE_AUDIT_PASS、LEADE_AUDIT_REFUSE、HR_PASS、HR_REFUSE。

▲第三步：使用状态机状态机的使用分两步走：

第一步:获取状态机实例

StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine = StateMachineFactory.get("leaveStateMachineId");

第二步：向状态机触发一个fireEvent事件

ApplyStatusEnum state=stateMachine.fireEvent(ApplyStatusEnum.LEAVE_SUBMIT, Event.EMPLOYEE_SUBMIT,context);

@DisplayName("员工提交请假申请单")
    @Test
    public void employSubmitRequest(){

        StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine = StateMachineFactory.get("leaveStateMachineId");
        LeaveContext context = new LeaveContext();

        ApplyStatusEnum state=stateMachine.fireEvent(ApplyStatusEnum.LEAVE_SUBMIT, Event.EMPLOYEE_SUBMIT,context);

        Assert.assertEquals(ApplyStatusEnum.LEAVE_SUBMIT.getCode(),state.getCode());

    }

    @DisplayName("部门主管审批通过")
    @Test
    public void leaderAuditPass(){

        StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine = StateMachineFactory.get("leaveStateMachineId");
        LeaveContext context = new LeaveContext();
        //主管审批通过
        context.setIdea(0);
        ApplyStatusEnum state=stateMachine.fireEvent(ApplyStatusEnum.LEAVE_SUBMIT, Event.DIRECTLEADER_AUDIT,context);
        Assert.assertEquals(ApplyStatusEnum.LEADE_AUDIT_PASS.getCode(),state.getCode());
    }

    @DisplayName("部门主管审批不通过")
    @Test
    public void leaderAuditNotPass(){

        StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine = StateMachineFactory.get("leaveStateMachineId");
        LeaveContext context = new LeaveContext();
        //主管审批不通过
        context.setIdea(1);
        ApplyStatusEnum state=stateMachine.fireEvent(ApplyStatusEnum.LEAVE_SUBMIT, Event.DIRECTLEADER_AUDIT,context);
        Assert.assertEquals(ApplyStatusEnum.LEADE_AUDIT_REFUSE.getCode(),state.getCode());
    }


    @DisplayName("HR审批通过")
    @Test
    public void hrAuditPass(){

        StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine = StateMachineFactory.get("leaveStateMachineId");
        LeaveContext context = new LeaveContext();
        //HR通过
        context.setIdea(0);
        ApplyStatusEnum state=stateMachine.fireEvent(ApplyStatusEnum.LEADE_AUDIT_PASS, Event.HR_AUDIT,context);
        Assert.assertEquals(ApplyStatusEnum.HR_PASS.getCode(),state.getCode());
    }

    @DisplayName("HR审批不通过")
    @Test
    public void hrAuditNotPass(){

        StateMachine<ApplyStatusEnum, Event, LeaveContext> stateMachine = StateMachineFactory.get("leaveStateMachineId");
        LeaveContext context = new LeaveContext();
        //HR审批不通过
        context.setIdea(1);
        ApplyStatusEnum state=stateMachine.fireEvent(ApplyStatusEnum.LEADE_AUDIT_PASS, Event.HR_AUDIT,context);
        Assert.assertEquals(ApplyStatusEnum.HR_REFUSE.getCode(),state.getCode());
    }

LEAVE_SUBMIT(1,"已申请"),
LEADE_AUDIT_PASS(2,"直属领导审批通过"),
LEADE_AUDIT_REFUSE(3,"直属领导审批失败"),
HR_PASS(4,"HR审批通过"),
HR_REFUSE(5,"HR审批拒绝");

github地址：https://github.com/TaoZhuGongBoy/enumstatemachine

▲核心语义模型

//StateMachine
public class StateMachineImpl<S,E,C> implements StateMachine<S, E, C> {

    private String machineId;
    //一个状态机持有多个状态（from、to)
    private final Map<S, State<S,E,C>> stateMap;

    ...
}

//State
public class StateImpl<S,E,C> implements State<S,E,C> {
    protected final S stateId;
    //同一个Event可以触发多个Transition
    private Map<E, List<Transition<S, E,C>>> transitions = new HashMap<>();
    
    ...
}
//Transition
public class TransitionImpl<S,E,C> implements Transition<S,E,C> {
    //源状态
    private State<S, E, C> source;
    //目标状态
    private State<S, E, C> target;
    //事件
    private E event;
    //条件
    private Condition<C> condition;
    //动作
    private Action<S,E,C> action;
    
    ...
}

▲源码解析

@Override
    public S fireEvent(S sourceStateId, E event, C ctx) {
        isReady();
        //根据sourceStateId找到符合条件的Transition
        Transition<S, E, C> transition = routeTransition(sourceStateId, event, ctx);

        if (transition == null) {
            Debugger.debug("There is no Transition for " + event);
            failCallback.onFail(sourceStateId, event, ctx);
            return sourceStateId;
        }
        //找到transition后执行transit方法(最终执行Action后返回目标State)
        return transition.transit(ctx, false).getId();
    }

/**
     * 路由Transition
     * @param sourceStateId 源状态ID
     * @param event 事件
     * @param ctx 上下文参数
     * @return
     */
    private Transition<S, E, C> routeTransition(S sourceStateId, E event, C ctx) {
        //根据源状态ID查找源状态实例
        State sourceState = getState(sourceStateId);

        //查找源状态实例下的流转列表
        List<Transition<S, E, C>> transitions = sourceState.getEventTransitions(event);

        if (transitions == null || transitions.size() == 0) {
            return null;
        }

        Transition<S, E, C> transit = null;
        for (Transition<S, E, C> transition : transitions) {
            if (transition.getCondition() == null) {
                transit = transition;
            } else if (transition.getCondition().isSatisfied(ctx)) {
                //一旦匹配when函数内的触发条件,返回transition
                transit = transition;
                break;
            }
        }

        return transit;
    }

@Override
    public State<S, E, C> transit(C ctx, boolean checkCondition) {
        Debugger.debug("Do transition: "+this);
        this.verify();
        //checkCondition为false或不指定when触发条件亦或匹配when触发条件；都将执行自定义的perform函数
        if (!checkCondition || condition == null || condition.isSatisfied(ctx)) {
            //如果自定义的perform函数有指定，将执行perform函数
            if(action != null){
                action.execute(source.getId(), target.getId(), event, ctx);
            }
            return target;
        }

        Debugger.debug("Condition is not satisfied, stay at the "+source+" state ");
        return source;
    }

▲写到最后