org.springframework.amqp.support.postprocessor.AbstractCompressingPostProcessor.java Source code

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Here is the source code for org.springframework.amqp.support.postprocessor.AbstractCompressingPostProcessor.java

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/*
 * Copyright 2014-2016 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.amqp.support.postprocessor;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

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

import org.springframework.amqp.AmqpException;
import org.springframework.amqp.AmqpIOException;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessagePostProcessor;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.core.Ordered;
import org.springframework.util.FileCopyUtils;

/**
 * Base class for post processors that compress the message body. The content encoding is
 * set to {@link #getEncoding()} or {@link #getEncoding()} + ":" + existing encoding, if
 * present.
 *
 * @author Gary Russell
 * @since 1.4.2
 */
public abstract class AbstractCompressingPostProcessor implements MessagePostProcessor, Ordered {

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

    private final boolean autoDecompress;

    private int order;

    /**
     * Construct a post processor that will include the
     * {@link MessageProperties#SPRING_AUTO_DECOMPRESS} header set to 'true'.
     */
    public AbstractCompressingPostProcessor() {
        this(true);
    }

    /**
     * Construct a post processor that will include (or not include) the
     * {@link MessageProperties#SPRING_AUTO_DECOMPRESS} header. Used by the (Spring AMQP) inbound
     * message converter to determine whether the message should be decompressed
     * automatically, or remain compressed.
     * @param autoDecompress true to indicate the receiver should automatically
     * decompress.
     */
    public AbstractCompressingPostProcessor(boolean autoDecompress) {
        this.autoDecompress = autoDecompress;
    }

    @Override
    public Message postProcessMessage(Message message) throws AmqpException {
        ByteArrayOutputStream zipped = new ByteArrayOutputStream();
        try {
            OutputStream zipper = getCompressorStream(zipped);
            FileCopyUtils.copy(new ByteArrayInputStream(message.getBody()), zipper);
            MessageProperties messageProperties = message.getMessageProperties();
            String currentEncoding = messageProperties.getContentEncoding();
            messageProperties
                    .setContentEncoding(getEncoding() + (currentEncoding == null ? "" : ":" + currentEncoding));
            if (this.autoDecompress) {
                messageProperties.setHeader(MessageProperties.SPRING_AUTO_DECOMPRESS, true);
            }
            byte[] compressed = zipped.toByteArray();
            if (this.logger.isTraceEnabled()) {
                this.logger.trace("Compressed " + message.getBody().length + " to " + compressed.length);
            }
            return new Message(compressed, messageProperties);
        } catch (IOException e) {
            throw new AmqpIOException(e);
        }
    }

    @Override
    public int getOrder() {
        return this.order;
    }

    /**
     * @param order the order, default 0.
     * @see Ordered
     */
    protected void setOrder(int order) {
        this.order = order;
    }

    /**
     * @param stream The output stream to write the compressed data to.
     * @return the compressor output stream.
     * @throws IOException IOException
     */
    protected abstract OutputStream getCompressorStream(OutputStream stream) throws IOException;

    /**
     * @return the content-encoding header.
     */
    protected abstract String getEncoding();

}