com.github.dxee.dject.event.guava.GuavaApplicationEventDispatcher Maven / Gradle / Ivy

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A collection of guice extensions, help to improve the developer experience of guice.

There is a newer version: 1.5.1

package com.github.dxee.dject.event.guava;

import com.github.dxee.dject.event.ApplicationEvent;
import com.github.dxee.dject.event.ApplicationEventDispatcher;
import com.github.dxee.dject.event.ApplicationEventListener;
import com.github.dxee.dject.event.ApplicationEventRegistration;
import com.google.common.eventbus.EventBus;
import com.google.common.reflect.TypeToken;

import javax.inject.Inject;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

final class GuavaApplicationEventDispatcher implements ApplicationEventDispatcher {

    private final EventBus eventBus;
    private final Method eventListenerMethod;

    @Inject
    public GuavaApplicationEventDispatcher(EventBus eventBus) {
        this.eventBus = eventBus;
        try {
            this.eventListenerMethod = ApplicationEventListener.class
                    .getDeclaredMethod("onEvent", ApplicationEvent.class);
        } catch (Exception e) {
            throw new RuntimeException("Failed to cache ApplicationEventListener method", e);
        }
    }

    public ApplicationEventRegistration registerListener(Object instance, Method method,
                                                         Class eventType) {
        GuavaSubscriberProxy proxy = new GuavaSubscriberProxy(instance, method, eventType);
        eventBus.register(proxy);
        return new GuavaEventRegistration(eventBus, proxy);
    }

    public  ApplicationEventRegistration registerListener(
            Class eventType, ApplicationEventListener eventListener) {
        GuavaSubscriberProxy proxy = new GuavaSubscriberProxy(eventListener, eventListenerMethod, eventType);
        eventBus.register(proxy);
        return new GuavaEventRegistration(eventBus, proxy);
    }

    public ApplicationEventRegistration registerListener(
            ApplicationEventListener eventListener) {
        Type[] genericInterfaces = eventListener.getClass().getGenericInterfaces();
        for (Type type : genericInterfaces) {
            if (ApplicationEventListener.class.isAssignableFrom(TypeToken.of(type).getRawType())) {
                ParameterizedType ptype = (ParameterizedType) type;
                Class rawType = TypeToken.of(ptype.getActualTypeArguments()[0]).getRawType();
                GuavaSubscriberProxy proxy = new GuavaSubscriberProxy(eventListener, eventListenerMethod, rawType);
                eventBus.register(proxy);
                return new GuavaEventRegistration(eventBus, proxy);
            }
        }
        return new ApplicationEventRegistration() {
            public void unregister() {}  //no-op. Could not find anything to register.
        };
    }

    @Override
    public void publishEvent(ApplicationEvent event) {
        this.eventBus.post(event);
    }
}