akka fsm matchEvent植入

Question

我试图理解AKKA "matchEvent“：

public final <ET> FSMStateFunctionBuilder<S, D> matchEvent(Class<ET> eventType, TypedPredicate2<ET, D> predicate, Apply2<ET, D, State<S, D>> apply) {
        return (new FSMStateFunctionBuilder()).event(eventType, predicate, apply);
    }

在查看http://doc.akka.io/japi/akka/2.3.4/index.html?akka/actor/AbstractFSM.html之后，我发现了以下内容：

public <P> FSMStateFunctionBuilder<S,D> event(java.lang.Class<P> eventType,
                                              FI.TypedPredicate2<P,D> predicate,
                                              FI.Apply2<P,D,FSM.State<S,D>> apply)

如果事件类型与谓词匹配，则添加匹配的case语句。参数: eventType --要在谓词上匹配的事件类型--将对数据进行计算和事件应用的谓词--一个应用于事件和状态数据(如果有匹配返回)的操作:添加了case语句的生成器。

有谁能告诉我，事件的匹配是如何实现的？

Answer 1

从docs 简单例子中提取

...
public class Buncher extends AbstractFSM<State, Data> {
{
  startWith(Idle, Uninitialized);

  when(Idle,
    matchEvent(SetTarget.class, Uninitialized.class,
      (setTarget, uninitialized) ->
        stay().using(new Todo(setTarget.getRef(), new LinkedList<>()))));

  // transition elided ...

  when(Active, Duration.create(1, "second"),
    matchEvent(Arrays.asList(Flush.class, StateTimeout()), Todo.class,
      (event, todo) -> goTo(Idle).using(todo.copy(new LinkedList<>()))));

  // unhandled elided ...

  initialize();
  }
}

Answer 2

如果您想表示基于传入事件字段或数据(或组合)的保护条件，请使用以下内容：

when(Active, Duration.create(1, "second"),
    matchEvent(Arrays.asList(Flush.class, StateTimeout()), Todo.class,
      (event, todo) -> todo.getQueue != null //any logical condition using event or data, 

      (event, todo) -> goTo(Idle).using(todo.copy(new LinkedList<>()))));