org.springframework.integration.gemfire.inbound.CacheListeningMessageProducer.java Source code

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Here is the source code for org.springframework.integration.gemfire.inbound.CacheListeningMessageProducer.java

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/*
 * Copyright 2002-2011 the original author or authors.
 *
 * Licensed 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.springframework.integration.gemfire.inbound;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.integration.endpoint.ExpressionMessageProducerSupport;
import org.springframework.integration.support.MessageBuilder;
import org.springframework.util.Assert;

import com.gemstone.gemfire.cache.CacheClosedException;
import com.gemstone.gemfire.cache.CacheListener;
import com.gemstone.gemfire.cache.EntryEvent;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.cache.util.CacheListenerAdapter;

/**
 * An inbound endpoint that listens to a GemFire region for events and then publishes Messages to
 * a channel. The default supported event types are CREATED and UPDATED. See the {@link EventType}
 * enum for all options. A SpEL expression may be provided to generate a Message payload by
 * evaluating that expression against the {@link EntryEvent} instance as the root object. If no
 * payloadExpression is provided, the {@link EntryEvent} itself will be the payload.
 *
 * @author Mark Fisher
 * @author David Turanski
 * @since 2.1
 */
@SuppressWarnings({ "rawtypes", "unchecked" })
public class CacheListeningMessageProducer extends ExpressionMessageProducerSupport {

    private final Log logger = LogFactory.getLog(this.getClass());

    private final Region region;

    private final CacheListener<?, ?> listener;

    private volatile Set<EventType> supportedEventTypes = new HashSet<EventType>(
            Arrays.asList(EventType.CREATED, EventType.UPDATED));

    public CacheListeningMessageProducer(Region<?, ?> region) {
        Assert.notNull(region, "region must not be null");
        this.region = region;
        this.listener = new MessageProducingCacheListener();
    }

    public void setSupportedEventTypes(EventType... eventTypes) {
        Assert.notEmpty(eventTypes, "eventTypes must not be empty");
        this.supportedEventTypes = new HashSet<EventType>(Arrays.asList(eventTypes));
    }

    @Override
    protected void doStart() {
        if (logger.isInfoEnabled()) {
            logger.info("adding MessageProducingCacheListener to GemFire Region '" + this.region.getName() + "'");
        }
        this.region.getAttributesMutator().addCacheListener(this.listener);
    }

    @Override
    protected void doStop() {
        if (logger.isInfoEnabled()) {
            logger.info(
                    "removing MessageProducingCacheListener from GemFire Region '" + this.region.getName() + "'");
        }
        try {
            this.region.getAttributesMutator().removeCacheListener(this.listener);
        } catch (CacheClosedException e) {
            if (logger.isDebugEnabled()) {
                logger.debug(e.getMessage(), e);
            }
        }

    }

    private class MessageProducingCacheListener extends CacheListenerAdapter {

        @Override
        public void afterCreate(EntryEvent event) {
            if (supportedEventTypes.contains(EventType.CREATED)) {
                this.processEvent(event);
            }
        }

        @Override
        public void afterUpdate(EntryEvent event) {
            if (supportedEventTypes.contains(EventType.UPDATED)) {
                this.processEvent(event);
            }
        }

        @Override
        public void afterInvalidate(EntryEvent event) {
            if (supportedEventTypes.contains(EventType.INVALIDATED)) {
                this.processEvent(event);
            }
        }

        @Override
        public void afterDestroy(EntryEvent event) {
            if (supportedEventTypes.contains(EventType.DESTROYED)) {
                this.processEvent(event);
            }
        }

        private void processEvent(EntryEvent event) {
            this.publish(evaluatePayloadExpression(event));

        }

        private void publish(Object payload) {
            sendMessage(MessageBuilder.withPayload(payload).build());
        }
    }

}