classutil.java

一个用java编写的服务器,对于学习网络编程的人来说是个很好的例子

/*
 * This file is part of the QuickServer library 
 * Copyright (C) 2003-2005 QuickServer.org
 *
 * Use, modification, copying and distribution of this software is subject to
 * the terms and conditions of the GNU Lesser General Public License. 
 * You should have received a copy of the GNU LGP License along with this 
 * library; if not, you can download a copy from <http://www.quickserver.org/>.
 *
 * For questions, suggestions, bug-reports, enhancement-requests etc.
 * visit http://www.quickserver.org
 *
 */

package org.quickserver.util; 

import java.util.*;
import java.io.*;
import java.net.*;
import org.quickserver.util.io.*;
import java.util.logging.*;

/**
 * A utility class to load class.
 * @author Akshathkumar Shetty
 * @since 1.3.2
 */
public class ClassUtil {
	private static Logger logger = Logger.getLogger(ClassUtil.class.getName());

	/**
	 * Tries to load the classes present in the array 
	 * passed has second parameter from
	 * the ClassLoader passed has first parameter.
	 * Returns the HashMap of all the classed successfully loaded.
	 * @param classLoader ClassLoader used to find the class
	 * @param classes[] array of classes to load. 
	 */
	public static Map loadClass(ClassLoader classLoader, String classNames[]) 
			throws Exception {
		Class classloded = null;
		HashMap classHash = new HashMap();
		for(int i=0;i<classNames.length;i++) {
			try	{
				classloded = classLoader.loadClass(classNames[i]);	
				classHash.put(classNames[i], classloded);
			} catch(Exception e) {
				logger.warning("Could not load classes : "+e);
			}						
		}
		return classHash;
	}

	/**
	 * Returns the ClassLoader to all the jars present in the 
	 * dir passed has first parameter.
	 * @param jarDir path to the directory containing the jars
	 */
	public static ClassLoader getClassLoaderFromJars(String jarDir) 
			throws Exception {
		logger.fine("Getting ClassLoader for jars in "+jarDir);
		File file = new File(jarDir);
		ArrayList list = new ArrayList();
		
		File jars[] =file.listFiles(new JarFileList());
		for(int j=0; j<jars.length;j++){
			list.add(jars[j].toURL());
		}

		Object array[] = list.toArray();
		URL jarurl[] = new URL[array.length];
		for(int i=0;i<array.length;i++) {
			jarurl[i] = (URL)array[i];
		}

		URLClassLoader classLoader = URLClassLoader.newInstance(jarurl);
		return classLoader;
	}

	/**
	 * Returns the ClassLoader to a jar
	 * @since 1.3.3
	 */
	public static ClassLoader getClassLoaderFromJar(String jarPath) 
			throws Exception {
		File file = new File(jarPath);
		logger.fine("Getting ClassLoader for "+file.getCanonicalPath());		
		URL jarurl[] = {file.toURL()};
		URLClassLoader classLoader = URLClassLoader.newInstance(jarurl);
		return classLoader;
	}

	/**
	 * Returns the ClassLoader
	 * @since 1.3.3
	 */
	public static ClassLoader getClassLoader(String path) throws Exception {
		File file = new File(path);
		if(file.canRead()==false) {
			logger.warning("Could not read path: "+path);
			return null;
		}
		if(file.isDirectory())
			return getClassLoaderFromJars(path);
		else
			return getClassLoaderFromJar(path);
	}
}