CustomZipAggregationStrategy.java

package com.ullgren.pontus.camel;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

import org.apache.camel.Exchange;
import org.apache.camel.component.file.FileConsumer;
import org.apache.camel.component.file.GenericFile;
import org.apache.camel.component.file.GenericFileMessage;
import org.apache.camel.component.file.GenericFileOperationFailedException;
import org.apache.camel.impl.DefaultEndpoint;
import org.apache.camel.processor.aggregate.AggregationStrategy;
import org.apache.camel.spi.Synchronization;
import org.apache.camel.util.FileUtil;

/**
 * This aggregation strategy will aggregate all incoming messages into a ZIP file.
 * <p>If the incoming exchanges contain {@link GenericFileMessage} file name will 
 * be taken from the body otherwise the body content will be treated as a byte 
 * array and the ZIP entry will be named using the message id.</p>
 * <p><b>Note:</b> Please note that this aggregation strategy requires eager 
 * completion check to work properly.</p>
 * 
 * @author Pontus Ullgren
 */
public class CustomZipAggregationStrategy implements AggregationStrategy {
	
	private String filePrefix = null;
	private String fileSuffix = ".zip";
	
	/**
	 * Gets the prefix used when creating the ZIP file name.
	 * @return the prefix
	 */
	public String getFilePrefix() {
		return filePrefix;
	}
	
	/**
	 * Sets the prefix that will be used when creating the ZIP filename.
	 * @param filePrefix prefix to use on ZIP file.
	 */
	public void setFilePrefix(String filePrefix) {
		this.filePrefix = filePrefix;
	}
	
	/**
	 * Gets the suffix used when creating the ZIP file name.
	 * @return the suffix
	 */
	public String getFileSuffix() {
		return fileSuffix;
	}
	/**
	 * Sets the suffix that will be used when creating the ZIP filename.
	 * @param fileSuffix suffix to use on ZIP file.
	 */
	public void setFileSuffix(String fileSuffix) {
		this.fileSuffix = fileSuffix;
	}

	@Override
	public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
		File zipFile;
		Exchange answer = oldExchange;
		
		// Guard against empty new exchanges
		if ( newExchange == null ) {
			return oldExchange;
		}
        
		// First time for this aggregation
        if (oldExchange == null) {
            try {
				zipFile = FileUtil.createTempFile(this.filePrefix, this.fileSuffix);
			} catch (IOException e) {
				throw new GenericFileOperationFailedException(e.getMessage(), e);
			}
			DefaultEndpoint endpoint = (DefaultEndpoint) newExchange.getFromEndpoint();
            answer = endpoint.createExchange();
            answer.addOnCompletion(new DeleteZipFileOnCompletion(zipFile));
        } else {
            zipFile = oldExchange.getIn().getBody(File.class);
        }
        
        // Handle GenericFileMessages
        if ( GenericFileMessage.class.isAssignableFrom(newExchange.getIn().getClass()) ) {
	        try {
				File appendFile =  newExchange.getIn().getBody(File.class);
				if ( appendFile != null ) {
					addFilesToZip(zipFile, new File[]{ appendFile });
					GenericFile<File> genericFile = FileConsumer.asGenericFile(zipFile.getParent(), zipFile, Charset.defaultCharset().toString());
		            genericFile.bindToExchange(answer);
		     	} else {
		     		throw new GenericFileOperationFailedException("Could not get body as file.");
				}
			} catch (IOException e) {
				throw new GenericFileOperationFailedException(e.getMessage(), e);
			}
        }
        // Handle all other messages
        else {
        	byte[] buffer = newExchange.getIn().getBody(byte[].class);
        	try {
				addEntryToZip(zipFile, newExchange.getIn().getMessageId(), buffer, buffer.length);
				GenericFile<File> genericFile = FileConsumer.asGenericFile(zipFile.getParent(), zipFile, Charset.defaultCharset().toString());
	            genericFile.bindToExchange(answer);
			} catch (IOException e) {
				throw new GenericFileOperationFailedException(e.getMessage(), e);
			}
        }
        
        return answer;
    }	
	
	private static void addFilesToZip(File source, File[] files) throws IOException
	{

        File tmpZip = File.createTempFile(source.getName(), null);
        tmpZip.delete();
        if(!source.renameTo(tmpZip))
        {
            throw new IOException("Could not make temp file (" + source.getName() + ")");
        }
        byte[] buffer = new byte[1024];
        ZipInputStream zin = new ZipInputStream(new FileInputStream(tmpZip));
        ZipOutputStream out = new ZipOutputStream(new FileOutputStream(source));

        for(int i = 0; i < files.length; i++)
        {
            InputStream in = new FileInputStream(files[i]);
            out.putNextEntry(new ZipEntry(files[i].getName()));
            for(int read = in.read(buffer); read > -1; read = in.read(buffer))
            {
                out.write(buffer, 0, read);
            }
            out.closeEntry();
            in.close();
        }

        for(ZipEntry ze = zin.getNextEntry(); ze != null; ze = zin.getNextEntry())
        {
            out.putNextEntry(ze);
            for(int read = zin.read(buffer); read > -1; read = zin.read(buffer))
            {
                out.write(buffer, 0, read);
            }
            out.closeEntry();
        }

        out.close();
        tmpZip.delete();
	}
	
	private static void addEntryToZip(File source, String entryName, byte[] buffer, int length) throws IOException
	{

        File tmpZip = File.createTempFile(source.getName(), null);
        tmpZip.delete();
        if(!source.renameTo(tmpZip))
        {
            throw new IOException("Could not make temp file (" + source.getName() + ")");
        }
        ZipInputStream zin = new ZipInputStream(new FileInputStream(tmpZip));
        ZipOutputStream out = new ZipOutputStream(new FileOutputStream(source));
        
        out.putNextEntry(new ZipEntry(entryName));
        out.write(buffer, 0, length);
        out.closeEntry();

        for(ZipEntry ze = zin.getNextEntry(); ze != null; ze = zin.getNextEntry())
        {
            out.putNextEntry(ze);
            for(int read = zin.read(buffer); read > -1; read = zin.read(buffer))
            {
                out.write(buffer, 0, read);
            }
            out.closeEntry();
        }

        out.close();
        tmpZip.delete();
	}
	
	/**
	 * This callback class is used to clean up the temporary ZIP file once the exchange has completed.
	 *
	 */
	private class DeleteZipFileOnCompletion implements Synchronization
	{
		
		private File fileToDelete;
		
		public DeleteZipFileOnCompletion(File fileToDelete) {
			this.fileToDelete = fileToDelete;
		}
		
		@Override
		public void onFailure(Exchange exchange) {
			// Keep the file if somthing gone a miss.
		}
		
		@Override
		public void onComplete(Exchange exchange) {
			FileUtil.deleteFile(this.fileToDelete);
		}
	}

}