org.wicketstuff.event.annotation.AnnotationEventDispatcher.java Source code

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Here is the source code for org.wicketstuff.event.annotation.AnnotationEventDispatcher.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.wicketstuff.event.annotation;

import org.apache.wicket.Application;
import org.apache.wicket.Component;
import org.apache.wicket.IEventDispatcher;
import org.apache.wicket.application.IComponentInstantiationListener;
import org.apache.wicket.event.IEvent;
import org.apache.wicket.util.collections.ClassMetaCache;

import java.lang.reflect.Method;

/**
 * <p>
 * Delivers events to any {@link Component} methods that are annotated with {@link OnEvent}
 * annotation and take exactly one parameter that matches the event payload type. To use this
 * dispatcher, you should register it as a component instantiation listener and an event dispatcher
 * in the application initialization, for example:
 * </p>
 * {@code
 * AnnotationEventDispatcher dispatcher = new AnnotationEventDispatcher();
 * getComponentInstantiationListeners().add(dispatcher);
 * getFrameworkSettings().add(dispatcher);
 * }
 */
public class AnnotationEventDispatcher implements IEventDispatcher, IComponentInstantiationListener {
    private static final AnnotationEventSink EMPTY_SINK = new AnnotationEventSink(Void.class);
    private final ClassMetaCache<AnnotationEventSink> eventSinkByClass = new ClassMetaCache<AnnotationEventSink>();

    @Override
    public void onInstantiation(final Component component) {
        Class<?> componentClass = component.getClass();
        if (eventSinkByClass.get(componentClass) == null) {
            if (containsOnEventMethod(componentClass)) {
                eventSinkByClass.put(componentClass, new AnnotationEventSink(componentClass));
            } else {
                eventSinkByClass.put(componentClass, EMPTY_SINK);
            }
        }
    }

    private boolean containsOnEventMethod(final Class<?> clazz) {
        for (Method method : clazz.getMethods()) {
            if (method.isAnnotationPresent(OnEvent.class)) {
                return true;
            }
        }
        return false;
    }

    @Override
    public void dispatchEvent(final Object sink, final IEvent<?> event, final Component component) {
        AnnotationEventSink eventSink = eventSinkByClass.get(sink.getClass());
        AnnotationEventDispatcherConfig config = Application.get()
                .getMetaData(Initializer.ANNOTATION_EVENT_DISPATCHER_CONFIG_CONTEXT_KEY);
        if (eventSink != null && eventSink != EMPTY_SINK && (config.getEventFilter() == null
                || config.getEventFilter().isAssignableFrom(event.getPayload().getClass()))) {
            eventSink.onEvent(sink, event);
        }
    }

}