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Diffstat (limited to 'src/java/org/apache/fop/events/DefaultEventBroadcaster.java')
| -rw-r--r-- | src/java/org/apache/fop/events/DefaultEventBroadcaster.java | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/src/java/org/apache/fop/events/DefaultEventBroadcaster.java b/src/java/org/apache/fop/events/DefaultEventBroadcaster.java new file mode 100644 index 000000000..bb1752a72 --- /dev/null +++ b/src/java/org/apache/fop/events/DefaultEventBroadcaster.java @@ -0,0 +1,160 @@ +/* + * 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. + */ + +/* $Id$ */ + +package org.apache.fop.events; + +import java.lang.reflect.InvocationHandler; +import java.lang.reflect.Method; +import java.lang.reflect.Proxy; +import java.util.Iterator; +import java.util.List; +import java.util.Map; + +import org.apache.xmlgraphics.util.Service; + +import org.apache.fop.events.model.EventMethodModel; +import org.apache.fop.events.model.EventModel; +import org.apache.fop.events.model.EventModelFactory; +import org.apache.fop.events.model.EventProducerModel; +import org.apache.fop.events.model.EventSeverity; + +/** + * Default implementation of the EventBroadcaster interface. It holds a list of event listeners + * and can provide {@link EventProducer} instances for type-safe event production. + */ +public class DefaultEventBroadcaster implements EventBroadcaster { + + /** Holds all registered event listeners */ + protected CompositeEventListener listeners = new CompositeEventListener(); + + /** {@inheritDoc} */ + public void addEventListener(EventListener listener) { + this.listeners.addEventListener(listener); + } + + /** {@inheritDoc} */ + public void removeEventListener(EventListener listener) { + this.listeners.removeEventListener(listener); + } + + /** {@inheritDoc} */ + public boolean hasEventListeners() { + return this.listeners.hasEventListeners(); + } + + /** {@inheritDoc} */ + public void broadcastEvent(Event event) { + this.listeners.processEvent(event); + } + + private static List/*<EventModel>*/ eventModels = new java.util.ArrayList(); + private Map proxies = new java.util.HashMap(); + + static { + Iterator iter = Service.providers(EventModelFactory.class, true); + while (iter.hasNext()) { + EventModelFactory factory = (EventModelFactory)iter.next(); + addEventModel(factory.createEventModel()); + } + } + + /** + * Adds a new {@link EventModel} to the list of registered event models. + * @param eventModel the event model instance + */ + public static void addEventModel(EventModel eventModel) { + eventModels.add(eventModel); + } + + /** {@inheritDoc} */ + public EventProducer getEventProducerFor(Class clazz) { + if (!EventProducer.class.isAssignableFrom(clazz)) { + throw new IllegalArgumentException( + "Class must be an implementation of the EventProducer interface: " + + clazz.getName()); + } + EventProducer producer; + producer = (EventProducer)this.proxies.get(clazz); + if (producer == null) { + producer = createProxyFor(clazz); + this.proxies.put(clazz, producer); + } + return producer; + } + + private EventProducerModel getEventProducerModel(Class clazz) { + for (int i = 0, c = eventModels.size(); i < c; i++) { + EventModel eventModel = (EventModel)eventModels.get(i); + EventProducerModel producerModel = eventModel.getProducer(clazz); + if (producerModel != null) { + return producerModel; + } + } + return null; + } + + /** + * Creates a dynamic proxy for the given EventProducer interface that will handle the + * conversion of the method call into the broadcasting of an event instance. + * @param clazz a descendant interface of EventProducer + * @return the EventProducer instance + */ + protected EventProducer createProxyFor(Class clazz) { + final EventProducerModel producerModel = getEventProducerModel(clazz); + if (producerModel == null) { + throw new IllegalStateException("Event model doesn't contain the definition for " + + clazz.getName()); + } + return (EventProducer)Proxy.newProxyInstance(clazz.getClassLoader(), + new Class[] {clazz}, + new InvocationHandler() { + public Object invoke(Object proxy, Method method, Object[] args) + throws Throwable { + String methodName = method.getName(); + EventMethodModel methodModel = producerModel.getMethod(methodName); + String eventID = producerModel.getInterfaceName() + "." + methodName; + if (methodModel == null) { + throw new IllegalStateException( + "Event model isn't consistent" + + " with the EventProducer interface. Please rebuild FOP!" + + " Affected method: " + + eventID); + } + Map params = new java.util.HashMap(); + int i = 1; + Iterator iter = methodModel.getParameters().iterator(); + while (iter.hasNext()) { + EventMethodModel.Parameter param + = (EventMethodModel.Parameter)iter.next(); + params.put(param.getName(), args[i]); + i++; + } + Event ev = new Event(args[0], eventID, methodModel.getSeverity(), params); + broadcastEvent(ev); + + if (ev.getSeverity() == EventSeverity.FATAL) { + EventExceptionManager.throwException(ev, + methodModel.getExceptionClass()); + } + return null; + } + }); + } + +} |