classloadersource.java

jcrontab是一个定时器开源项目包 目前提供存取文件或数据库, 把执行结果寄发 email, 简单地设置在 Tomcat, Resin, Jetty 及 JBoss 之上, 更是可以取代 cron

/**
 *  This file is part of the jcrontab package
 *  Copyright (C) 2001-2003 Sergey V. Oudaltsov
 *
 *  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
 *
 *  For questions, suggestions:
 *
 *  [e-mail]
 *
 */

package org.jcrontab.data;

import java.io.InputStream;
import java.io.IOException;

/**
 * This class Is the implementation of DataSource to access 
 * Info in a FileSystem
 * @author $Author: iolalla $
 * @version $Revision: 1.2 $
 */
public class ClassLoaderSource extends FileSource {

    private static ClassLoaderSource instance;
    
    public synchronized DataSource getInstance() {
		if (instance == null) {
		instance = new ClassLoaderSource();
		}
		return instance;
    }
	
	protected InputStream createCrontabStream(String name) throws IOException {
		final InputStream input = ClassLoaderSource.class.getClassLoader().getResourceAsStream(name);
		if (input == null)
			throw new IOException("Resource " + name + " not found");
		return input;
	}

	protected boolean isChanged(String name) {
		final boolean rv = lastModified == 0L;
		if (rv)
		// This line is added to avoid reading the file if it didn't 
		// change
			lastModified = System.currentTimeMillis();
		return rv;
	}
}