org.springframework.integration.endpoint.EventDrivenConsumer.java Source code

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Here is the source code for org.springframework.integration.endpoint.EventDrivenConsumer.java

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/*
 * Copyright 2002-2019 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
 *
 *      https://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.endpoint;

import org.springframework.context.Lifecycle;
import org.springframework.integration.core.MessageProducer;
import org.springframework.integration.router.MessageRouter;
import org.springframework.integration.support.context.NamedComponent;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHandler;
import org.springframework.messaging.SubscribableChannel;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Message Endpoint that connects any {@link MessageHandler} implementation to a {@link SubscribableChannel}.
 *
 * @author Mark Fisher
 * @author Oleg Zhurakousky
 * @author Gary Russell
 */
public class EventDrivenConsumer extends AbstractEndpoint implements IntegrationConsumer {

    private final SubscribableChannel inputChannel;

    private final MessageHandler handler;

    public EventDrivenConsumer(SubscribableChannel inputChannel, MessageHandler handler) {
        Assert.notNull(inputChannel, "inputChannel must not be null");
        Assert.notNull(handler, "handler must not be null");
        this.inputChannel = inputChannel;
        this.handler = handler;
        this.setPhase(Integer.MIN_VALUE);
    }

    @Override
    public MessageChannel getInputChannel() {
        return this.inputChannel;
    }

    @Override
    public MessageChannel getOutputChannel() {
        if (this.handler instanceof MessageProducer) {
            return ((MessageProducer) this.handler).getOutputChannel();
        } else if (this.handler instanceof MessageRouter) {
            return ((MessageRouter) this.handler).getDefaultOutputChannel();
        } else {
            return null;
        }
    }

    @Override
    public MessageHandler getHandler() {
        return this.handler;
    }

    @Override
    protected void doStart() {
        this.logComponentSubscriptionEvent(true);
        this.inputChannel.subscribe(this.handler);
        if (this.handler instanceof Lifecycle) {
            ((Lifecycle) this.handler).start();
        }
    }

    @Override
    protected void doStop() {
        this.logComponentSubscriptionEvent(false);
        this.inputChannel.unsubscribe(this.handler);
        if (this.handler instanceof Lifecycle) {
            ((Lifecycle) this.handler).stop();
        }
    }

    private void logComponentSubscriptionEvent(boolean add) {
        if (this.handler instanceof NamedComponent && this.inputChannel instanceof NamedComponent) {
            String channelName = ((NamedComponent) this.inputChannel).getComponentName();
            String componentType = ((NamedComponent) this.handler).getComponentType();
            componentType = StringUtils.hasText(componentType) ? componentType : "";
            String componentName = getComponentName();
            componentName = (StringUtils.hasText(componentName) && componentName.contains("#")) ? ""
                    : ":" + componentName;
            StringBuffer buffer = new StringBuffer();
            buffer.append(
                    "{" + componentType + componentName + "} as a subscriber to the '" + channelName + "' channel");
            if (add) {
                buffer.insert(0, "Adding ");
            } else {
                buffer.insert(0, "Removing ");
            }
            logger.info(buffer.toString());
        }
    }
}