EventSourceHandler被错误的事件触发？

Question

我设计了两个输入命令scheduleletterCommand，它们将在几分钟内“发送一封信”...如果用户在该时间段内发送另一个命令cancelletterCommand，则可以取消该命令。

我正在通过REST API控制器触发命令...

我希望看到的是日志语句，如果我计划一封信，并在接下来的五分钟内立即取消它，这些语句表示一封信被计划和取消。

Received schedule command for letter id e6e037be-3b6d-4ae3-80cd-12426adcd526
LetterScheduledEvent e6e037be-3b6d-4ae3-80cd-12426adcd526 SCHEDULED

LetterScheduledEvent e6e037be-3b6d-4ae3-80cd-12426adcd526 SCHEDULED
Received cancel command for letter id e6e037be-3b6d-4ae3-80cd-12426adcd526
Letter e6e037be-3b6d-4ae3-80cd-12426adcd526 cancelled CANCELLED

这是我的集合体-

java prettyprint-override">public class Letter {

    @AggregateIdentifier
    private String letterId;
    private ScheduleToken scheduleToken;

    @SuppressWarnings("UnusedDeclaration")
    protected Letter() {
        // Default constructor required by Axon Framework
    }

    @CommandHandler
    public Letter(ScheduleLetterCommand cmd, EventScheduler scheduler) {
        String id = cmd.getLetterId();
        log.info("Received schedule command for letter id {}", letterId);
        AggregateLifecycle.apply(new LetterScheduledEvent(id, LetterEventType.SCHEDULED));
        this.scheduleToken = scheduler.schedule(Duration.ofMinutes(5), new BeginSendLetterEvent(id,LetterEventType.BEGIN_SEND));
    }

    @CommandHandler
    public void handle(CancelLetterCommand cmd, EventScheduler eventScheduler) {
        String letterId = cmd.getLetterId();
        log.info("Received cancel command for letter id {}", letterId);
        AggregateLifecycle.apply(new LetterCancelledEvent(letterId, LetterEventType.CANCELLED));
        eventScheduler.cancelSchedule(scheduleToken);
    }

    @EventSourcingHandler
    public void on(LetterScheduledEvent event) {
        log.info("LetterScheduledEvent {} {}", event.getLetterId(), event.getEventType());
        this.letterId = event.getLetterId();
    }

    @EventSourcingHandler
    public void on(LetterCancelledEvent event) {
        log.info("Letter {} cancelled {}", event.getLetterId(), event.getEventType());
        scheduleToken = null;
    }

    @EventSourcingHandler
    public void on(BeginSendLetterEvent event) {
        log.info("Letter sending process started {} {}", event.getLetterId(), event.getEventType());
        //complicated letter sending processes...
        AggregateLifecycle.apply(new LetterSentEvent(event.getLetterId(), LetterEventType.SENT));
    }

    @EventSourcingHandler
    public void on(LetterSentEvent event) {
        log.info("Letter sent {} {}", event.getLetterId(), event.getEventType());
    }
}

这是我的活动->

abstract class LetterMovementEvent(open val letterId: String, open val eventType: LetterEventType)

enum class LetterEventType {
    SCHEDULED,
    CANCELLED,
    BEGIN_SEND,
    SENT
}

data class LetterScheduledEvent(
        override val letterId: String,
        override val eventType: LetterEventType = LetterEventType.SCHEDULED
) : LetterMovementEvent(letterId, eventType)

data class LetterCancelledEvent(
        override val letterId: String,
        override val eventType: LetterEventType = LetterEventType.CANCELLED
) : LetterMovementEvent(letterId, eventType)

data class BeginSendLetterEvent(
        override val letterId: String,
        override val eventType: LetterEventType = LetterEventType.BEGIN_SEND
) : LetterMovementEvent(letterId, eventType)

data class LetterSentEvent(
        override val letterId: String,
        override val eventType: LetterEventType = LetterEventType.SENT
) : LetterMovementEvent(letterId, eventType)

Answer 1

你所注意到的@goldfish，是一个框架，它根据它已经发布的事件来获取你的聚合。因此，简而言之，您正在看到“活动来源在行动”。

通过字母聚合中的@eventsourcinghandler注释，您已经有效地创建了用于根据事件重新创建聚合的方法。

因此，如果您发送一个命令来取消这个聚合的字母，它将首先从事件中重新创建聚合。只有在解决了这个问题之后，才会真正将命令赋予@commandhandler注释方法。