001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.component.event;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Processor;
021    import org.apache.camel.Producer;
022    import org.apache.camel.impl.DefaultEndpoint;
023    import org.apache.camel.impl.DefaultProducer;
024    import org.apache.camel.processor.loadbalancer.LoadBalancer;
025    import org.apache.camel.processor.loadbalancer.TopicLoadBalancer;
026    import org.apache.camel.util.ObjectHelper;
027    import org.springframework.beans.BeansException;
028    import org.springframework.context.ApplicationContext;
029    import org.springframework.context.ApplicationContextAware;
030    import org.springframework.context.ApplicationEvent;
031    
032    import static org.apache.camel.util.ObjectHelper.wrapRuntimeCamelException;
033    
034    
035    /**
036     * An <a href="http://camel.apache.org/event.html">Event Endpoint</a>
037     * for working with Spring ApplicationEvents
038     *
039     * @version $Revision: 781349 $
040     */
041    public class EventEndpoint extends DefaultEndpoint implements ApplicationContextAware {
042        private LoadBalancer loadBalancer;
043        private ApplicationContext applicationContext;
044    
045        public EventEndpoint(String endpointUri, EventComponent component) {
046            super(endpointUri, component);
047            this.applicationContext = component.getApplicationContext();
048        }
049    
050        public EventEndpoint(String endpointUri) {
051            super(endpointUri);
052        }
053    
054        public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
055            this.applicationContext = applicationContext;
056        }
057    
058        public ApplicationContext getApplicationContext() {
059            return applicationContext;
060        }
061    
062        public boolean isSingleton() {
063            return true;
064        }
065    
066        public Producer createProducer() throws Exception {
067            ObjectHelper.notNull(applicationContext, "applicationContext");
068            return new DefaultProducer(this) {
069                public void process(Exchange exchange) throws Exception {
070                    ApplicationEvent event = toApplicationEvent(exchange);
071                    applicationContext.publishEvent(event);
072                }
073            };
074        }
075    
076        public EventConsumer createConsumer(Processor processor) throws Exception {
077            ObjectHelper.notNull(applicationContext, "applicationContext");
078            return new EventConsumer(this, processor);
079        }
080    
081        public void onApplicationEvent(ApplicationEvent event) {
082            Exchange exchange = createExchange();
083            exchange.getIn().setBody(event);
084            try {
085                getLoadBalancer().process(exchange);
086            } catch (Exception e) {
087                throw wrapRuntimeCamelException(e);
088            }
089        }
090    
091        public LoadBalancer getLoadBalancer() {
092            if (loadBalancer == null) {
093                loadBalancer = createLoadBalancer();
094            }
095            return loadBalancer;
096        }
097    
098        public void setLoadBalancer(LoadBalancer loadBalancer) {
099            this.loadBalancer = loadBalancer;
100        }
101    
102        // Implementation methods
103        // -------------------------------------------------------------------------
104        public synchronized void consumerStarted(EventConsumer consumer) {
105            getLoadBalancer().addProcessor(consumer.getProcessor());
106        }
107    
108        public synchronized void consumerStopped(EventConsumer consumer) {
109            getLoadBalancer().removeProcessor(consumer.getProcessor());
110        }
111    
112        protected LoadBalancer createLoadBalancer() {
113            return new TopicLoadBalancer();
114        }
115    
116        protected ApplicationEvent toApplicationEvent(Exchange exchange) {
117            ApplicationEvent event = exchange.getIn().getBody(ApplicationEvent.class);
118            if (event != null) {
119                return event;
120            }
121            return new CamelEvent(this, exchange);
122        }
123    }