Question

我使用Spring StateMachineBuilder来创建Bean。

在机器中，我有一个Action，它每秒重复一次。

这是用于演示的最小构建器代码：

@Bean
public StateMachine<State, Event> getStateMachine() throws Exception {
    Action action = s -> {};
    Builder<State, Event> builder = StateMachineBuilder.builder();

    builder.configureConfiguration()
            .withConfiguration()
            .autoStartup(true)
            .taskExecutor(new SyncTaskExecutor())
            .taskScheduler(new ConcurrentTaskScheduler());

    builder.configureStates()
            .withStates()
            .initial(State.STARTING)
            .state(State.ACTION, action, null)
            .end(State.DONE)
            .states(EnumSet.allOf(State.class));

    builder.configureTransitions()
            .withExternal()
            .source(State.STARTING).target(State.ACTION).event(Event.START)
            .and().withInternal()
            .source(State.ACTION)
            .action(action)
            .timer(1000)

            .and().withExternal()
            .source(State.ACTION).target(State.DONE).event(Event.STOP);

    return builder.build();
}

无法创建bean，我收到此错误：

Caused by: java.lang.NullPointerException
    at org.springframework.statemachine.trigger.TimerTrigger.doStart(TimerTrigger.java:51)
    at org.springframework.statemachine.support.LifecycleObjectSupport.start(LifecycleObjectSupport.java:120)
    at org.springframework.statemachine.support.DefaultStateMachineExecutor.registerTriggerListener(DefaultStateMachineExecutor.java:415)
    at org.springframework.statemachine.support.DefaultStateMachineExecutor.<init>(DefaultStateMachineExecutor.java:116)
    at org.springframework.statemachine.support.AbstractStateMachine.onInit(AbstractStateMachine.java:258)
    at org.springframework.statemachine.support.LifecycleObjectSupport.afterPropertiesSet(LifecycleObjectSupport.java:67)
    at org.springframework.statemachine.config.ObjectStateMachineFactory.buildStateMachineInternal(ObjectStateMachineFactory.java:79)
    at org.springframework.statemachine.config.AbstractStateMachineFactory.buildMachine(AbstractStateMachineFactory.java:547)
    at org.springframework.statemachine.config.AbstractStateMachineFactory.getStateMachine(AbstractStateMachineFactory.java:193)
    at org.springframework.statemachine.config.StateMachineBuilder$Builder.build(StateMachineBuilder.java:128)

如果我删除withInternal() [...] .timer(1000)，它会有效，但我会失去重复功能。

我的构建器代码有什么问题？

Answer 1

我相信这是春天状态机的一个错误。只有在使用StateMachineBuilder而不是使用springboot配置StateMachine时才会发生这种情况。

在AbstractStateMachineFactory.java中，当它创建一个新实例时，它不会在TimerTrigger上设置taskScheduler。我能够通过添加：

来解决这个问题

AbstractStateMachineFactory.java : 547

if( taskScheduler != null )
{
  t.setTaskScheduler(taskScheduler);
}

我在此处#178向项目提交了拉取请求。

崩溃的StateMachineBuilder计时器

1 个答案: