abstractiomanager.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.io.*;


/**
 * Abstract superclass for IOManager implementations.
 * @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 abstract class AbstractIOManager implements IOManager{
	/**
	 * Read data into a byte buffer.
	 * @param in an input stream
	 * @return an array of bytes
	 */
	protected byte[] readData(InputStream in) throws IOException {
		int c = -1;
		ByteArrayOutputStream bout = new ByteArrayOutputStream();
		while ((c=in.read())!=-1) bout.write(c); // TODO improve efficiency
		return bout.toByteArray();
	}
	/**
	 * Log and (re-)throw an exception.
	 * @param msg the exception message
	 * @param x the cause
	 */
	protected void error(String msg,Exception x) throws ZKBException{
		LOG_ZKB.error(msg);
		throw new ZKBException(msg,x);
	}
	/**
	 * Log and (re-)throw an exception.
	 * @param msg the exception message
	 */
	protected void error(String msg) throws ZKBException{
		error(msg,null);
	}
	
	/**
	 * Get the ops.
	 * @param metaData meta data
	 * @return teh OPS used
	 */
	protected ObjectPersistencyService getOPS(Properties metaData) throws ZKBException {
		String opsClassName = metaData.getProperty(ZKBManager.OPS);
		ObjectPersistencyService ops = null;
		try {
			LOG_ZKB.debug("Using OPS : " + opsClassName) ;
			ops = (ObjectPersistencyService)Class.forName(opsClassName).newInstance();
			return ops;
		}
		catch (ClassNotFoundException x) {
			error("Cannot find class " + opsClassName,x);
		}  
		catch (InstantiationException x) {
			error("Cannot instanciate " + opsClassName,x);
		}  		
		catch (IllegalAccessException x) {
			error("Cannot access class " + opsClassName,x);
		}  
		return null;
	}
}