class ClassLoaderFactory

package org.apache.catalina.startup;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.apache.catalina.loader.StandardClassLoader;


/**
 * Utility class for building class loaders for Catalina.  The factory
 * method requires the following parameters in order to build a new class
 * loader (with suitable defaults in all cases):
 

 
A set of directories containing unpacked classes (and resources)
     that should be included in the class loader's
     repositories.
 
A set of directories containing classes and resources in JAR files.
     Each readable JAR file discovered in these directories will be
     added to the class loader's repositories.
 
ClassLoader instance that should become the parent of
     the new class loader.
 
 *
 * @author Craig R. McClanahan
 * @version $Revision: 1.8 $ $Date: 2002/02/17 08:26:02 $
 */


public final class ClassLoaderFactory {


 
   /**
     * Debugging detail level for processing the startup.
     */

    private static int debug = 0;



    /**
     * Return the debugging detail level.
     */

    public static int getDebug() {
        return (debug);
    }



    /**
     * ����DEBUG����
     */

    public static void setDebug(int newDebug) {
        debug = newDebug;
    }



    /**
     * ������һ����̬�࣬���������ͷ���ClassLoader����ʵ������StandardClassLoader����
     * �����������úͲ�������apache���õ�ClassLoader����������Լ���������
     *
     * @param unpacked ��·��CLASSPATH������
     * @param packed ����JAR�ļ�����·��
     * @param parent ��ClassLoader���󡣵�һ��ClassLoader�����޷����������ʱ���������󸸶������
     *
     * @exception Exception if an error occurs constructing the class loader
     */

    public static ClassLoader createClassLoader(File unpacked[],
                                                File packed[],
                                                ClassLoader parent)
        throws Exception {

        if (debug >= 1)
            log("Creating new class loader");


        // list�ｫ������������Ҫ���ӵ�CLASSPATH��ȥ���ļ���

        ArrayList list = new ArrayList();


        // Add unpacked directories

        if (unpacked != null) {
            for (int i = 0; i < unpacked.length; i++)  {
                File file = unpacked[i];
                if (!file.isDirectory() || !file.exists() || !file.canRead())
                    continue;
                if (debug >= 1)
                    log("  Including directory " + file.getAbsolutePath());
                URL url = new URL("file", null,
                                  file.getCanonicalPath() + File.separator);
                list.add(url.toString());
            }
        }


        // Add packed directory JAR files

        if (packed != null) {
            for (int i = 0; i < packed.length; i++) {
                File directory = packed[i];
                if (!directory.isDirectory() || !directory.exists() ||
                    !directory.canRead())
                    continue;
                String filenames[] = directory.list();
                for (int j = 0; j < filenames.length; j++) {
                    String filename = filenames[j].toLowerCase();
                    if (!filename.endsWith(".jar"))
                        continue;
                    File file = new File(directory, filenames[j]);
                    if (debug >= 1)
                        log("  Including jar file " + file.getAbsolutePath());
                    URL url = new URL("file", null,
                                      file.getCanonicalPath());
                    list.add(url.toString());
                }
            }
        }
        

        // �����list



        // ����StandardClassLoader���󣬲�����

        String array[] = (String[]) list.toArray(new String[list.size()]);
        StandardClassLoader classLoader = null;
        if (parent == null)
            classLoader = new StandardClassLoader(array);
        else
            classLoader = new StandardClassLoader(array, parent);
        classLoader.setDelegate(true);
        return (classLoader);

    }



    /**
     * �����־
     */

    private static void log(String message) {
        System.out.print("ClassLoaderFactory:  ");
        System.out.println(message);
    }



    /**
     * �����־���쳣��Ϣ
     */

    private static void log(String message, Throwable exception) {
        log(message);
        exception.printStackTrace(System.out);
    }

}