我有以下界面:
public interface ResultEvaluationInterface {
public void evaluateResults(Event e);
}
我希望在我的课程中注入,具体取决于我的Event.type
个不同的类。这样的事情:
@Stateless
@LocalBean
public class ResultEvaluation implements ResultEvaluationInterface {
@Override
public void evaluateResults(Event e) {
switch (e.getType()) {
case Type.Running:
// inject and call ResultEvaluationRunningEJB.evaluateResults(e)
case Type.Swimming:
// inject and call ResultEvaluationSwimmingEJB.evaluateResults(e)
default:
throw new UnsupportedOperationException("Not supported yet.");
}
}
}
ResultEvaluationRunningEJB
和ResultEvaluationSwimmingEJB
都实现了界面。有人知道怎么做得好吗?
答案 0 :(得分:2)
如果您真的想使用硬编码if语句在prod和dev事件之间切换,可以使用CDI限定符,只需将两个实现注入Facade:
@Stateless
@LocalBean
public class ResultEvaluationFacade {
@Inject
@Development
private ResultEvalutationInterface dev;
@Inject
@Production
private ResultEvalutionInterface prod;
@Override
public void evaluateResults(Event e) {
switch (e.getType()) {
case Type.Production:
prod.evaluteResult(e);
break;
case Type.Development:
dev.evaluteResult(e);
break;
default:
throw new UnsupportedOperationException("Not supported yet.");
}
}
}
定义您的两个实现:
@Development
public class ResultEvaluationDevelopment implements ResultEvaluationInterface {
...
}
@Production
public class ResultEvaluationDevelopment implements ResultEvaluationInterface {
...
}
但是我会考虑使用模拟maven项目代替两个单独的实现。
或者你可以使用不同的CDI事件类型,如下所示。
public void observeDevEvent(@Observe DevEvent event) {
//do stuff.
}
public void observeProdEvent(@Observe ProdEvent event) {
//do stuff
}
点燃活动看起来像这样:
@Inject
private Event<ProdEvent> prodEvent;
public void someMethod() {
ProdEvent pe = new ProdEvent()
// set some data on ProdEvent
prodEvent.fire(pe);
}
注意事件也适用于限定符,因此您还可以向事件添加限定符注释,而不是实现两种不同类型的事件。
@Inject
@Production
private Event<MyEvent> event;
听@Prodcution事件;
public void handleProdEvent(@Observer @Production MyEvent myEvent) {
// do Stuff.
}
对于bean的延迟实例化,您可以使用CDI实例注入。
@Inject
private Instance<BeanA> beanA;
....
public void doStuff(Event e) {
...
case Type.Production:
//lazily evaluates and instantiatiates bean.
beanA.get().evaluateResult(e);
}
答案 1 :(得分:0)
注意:我还没有确认这是有效的,但你应该能够解决这个问题。
您可以使用动态CDI事件分派:
public class EventDispatcher {
@Inject
BeanManager beanManager;
public void handle(MyEvents mytype) {
beanManager.fireEvent(mytype, mytype.getQualifiyer());
}
}
您可以在活动枚举中引用您的限定词:
public enum MyEvents {
EVENTA(new EventA() {
@Override
public Class<? extends Annotation> annotationType() {
return this.getClass();
}
}),
EVENTB (new EventB() {
@Override
public Class<? extends Annotation> annotationType() {
return this.getClass();
}
});
private final Annotation annotation;
MyEvents(Annotation annotation) {
this.annotation = annotation;
}
public Annotation getQualifiyer() {
return annotation;
}
};
限定符看起来像这样:
@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PARAMETER,ElementType.FIELD})
public @interface EventA {
}
这样你就可以简单地将观察者方法添加到事件处理bean中:
public class EventProcessorA {
...
public void handleEvent(@Observer @BeanA MyEvents myevent) {
...
}
}
而不是在一个带有巨型切换语句的调度程序中注入20-30。