zipiomanager.java

Mandarax是一个规则引擎的纯Java实现。它支持多类型的事实和基于反映的规则

/*
 * Copyright (C) 1999-2005 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.mandarax.zkb;

import java.util.Properties;
import java.util.zip.*;
import java.util.jar.*;
import java.io.*;
import java.net.URL;

import org.mandarax.zkb.IOManager.Data;

/**
 * IO Manager implementation based on zip / jar files.
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 3.4
 */

public class ZIPIOManager extends AbstractIOManager {
	/**
	 * Write zkb data.
	 * @param target an object describing the target (e.g. a file)
	 * @param metaData the serialized meta data
	 * @param kbData the serialized knowledge base
	 * @param ops the object persistency service used
	 * @param resourceData the serialized resource data (objects)
	 */
	public void write(Object target,byte[] metaData, byte[] kbData, byte[] resourceData,ObjectPersistencyService ops) throws Exception {
		OutputStream out = null;
		if (target instanceof File) {
			File f = (File)target;
			if (f.isDirectory()) throw new IllegalArgumentException("target must not be a directory");
			else out = new FileOutputStream(f);
		}
		else if (target instanceof OutputStream) out = (OutputStream)target;
		else throw new IllegalArgumentException("This target type is not support: " + target);

		JarOutputStream jarOut = new JarOutputStream(out);
		
		JarEntry entry =  new JarEntry(META);
		jarOut.putNextEntry(entry);
		jarOut.write(metaData);
		jarOut.closeEntry();
		
		entry =  new JarEntry(RESOURCES + "." + ops.getExtension());
		jarOut.putNextEntry(entry);
		jarOut.write(resourceData);
		jarOut.closeEntry();
		
		entry =  new JarEntry(KB);
		jarOut.putNextEntry(entry);
		jarOut.write(kbData);
		jarOut.closeEntry();
		
		jarOut.close();
		out.close();
		
	}
	
	/**
	 * Read zkb data.
	 * @param source the data source (e.g., a file)
	 * @return a data object
	 */
	public Data read(Object source) throws Exception {
		Data result = new Data();
		File f = null;
		InputStream in = null;
		
		if (source instanceof File) {
			f = (File)source;
			if (f.isDirectory()) {
				throw new IllegalArgumentException("target must not be a directory");
			}
			else in = new FileInputStream(f);
		}
		else if (source instanceof InputStream) in = (InputStream)source;
		else if (source instanceof URL) in = ((URL)source).openStream();
		else throw new IllegalArgumentException("This source type is not support: " + source);

		JarInputStream jarIn = new JarInputStream(in);
		
		// meta data
		byte[] metaData = this.readFromZip(jarIn,META);
		
		// read extension for resource file from meta data
		result.metaData = new Properties();
		result.metaData.load(new ByteArrayInputStream(metaData));
		result.ops = getOPS(result.metaData);
		
		result.resourceData = this.readFromZip(jarIn,RESOURCES+"."+result.ops.getExtension());
		result.kbData = this.readFromZip(jarIn,KB);

		jarIn.close();
		in.close();
		
		return result;
	}


	/**
	 * Read the next piece of data from a zip file.
	 * @param jarIn the jar input stream
	 * @param expectedName the expected name of the next zip entry
	 * @return an array of bytes
	 */
	private byte[] readFromZip(JarInputStream jarIn,String expectedName) throws ZKBException {
		// kb
		try {
			JarEntry jarEntry = jarIn.getNextJarEntry();
			if (!jarEntry.getName().equals(expectedName)) {
				error("Zip entry " + expectedName + " expected but " + jarEntry.getName() + " found");
			}
			byte[] data = readData(jarIn);	
			jarIn.closeEntry();
			return data;
		}
		catch (IOException x) {
			error("Cannot read zkb kb from zip entry",x);
		}
		return new byte[0];
	}

}