org.springframework.integration.channel.FixedSubscriberChannel.java Source code

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Here is the source code for org.springframework.integration.channel.FixedSubscriberChannel.java

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/*
 * Copyright 2014-2019 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.channel;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.BeanNameAware;
import org.springframework.integration.support.context.NamedComponent;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHandler;
import org.springframework.messaging.MessagingException;
import org.springframework.messaging.SubscribableChannel;

/**
 * Specialized {@link SubscribableChannel} for a single final subscriber set up during bean instantiation (unlike
 * other {@link SubscribableChannel}s where the {@link MessageHandler} is subscribed when the endpoint
 * is started). This channel does not support interceptors or data types.
 * <p>
 * <b>Note: Stopping ({@link #unsubscribe(MessageHandler)}) the subscribed ({@link MessageHandler}) has no effect.</b>
 *
 * @author Gary Russell
 * @author Artem Bilan
 *
 * @since 4.0
 *
 */
public final class FixedSubscriberChannel implements SubscribableChannel, BeanNameAware, NamedComponent {

    private static final Log LOGGER = LogFactory.getLog(FixedSubscriberChannel.class);

    private final MessageHandler handler;

    private String beanName;

    public FixedSubscriberChannel() {
        throw new IllegalArgumentException(
                "Cannot instantiate a " + this.getClass().getSimpleName() + " without a MessageHandler.");
    }

    public FixedSubscriberChannel(MessageHandler handler) {
        this.handler = handler;
    }

    @Override
    public void setBeanName(String name) {
        this.beanName = name;
    }

    @Override
    public String getBeanName() {
        return this.beanName;
    }

    @Override
    public boolean send(Message<?> message) {
        return send(message, 0);
    }

    @Override
    public boolean send(Message<?> message, long timeout) {
        try {
            this.handler.handleMessage(message);
            return true;
        } catch (RuntimeException e) {
            if (e instanceof MessagingException && ((MessagingException) e).getFailedMessage() == null) {
                throw new MessagingException(message, "Failed to handle Message", e);
            } else {
                throw e;
            }
        }
    }

    @Override
    public boolean subscribe(MessageHandler handler) {
        if (handler != this.handler && LOGGER.isDebugEnabled()) {
            LOGGER.debug(getComponentName() + ": cannot be subscribed to (it has a fixed single subscriber).");
        }
        return false;
    }

    @Override
    public boolean unsubscribe(MessageHandler handler) {
        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug(getComponentName() + ": cannot be unsubscribed from (it has a fixed single subscriber).");
        }
        return false;
    }

    @Override
    public String getComponentType() {
        return "fixed-subscriber-channel";
    }

    @Override
    public String getComponentName() {
        if (this.beanName != null) {
            return this.beanName;
        } else {
            return "Unnamed fixed subscriber channel";
        }
    }

}