/** Copyright (c) 1997-1999 Bill Venners. All rights reserved.** Source code file from the book "Inside the Java 2 Virtual Machine,"* by Bill Venners, published by McGraw-Hill, 1999, ISBN: 0-07-135093-4. ** This source file may not be copied, modified, or redistributed* EXCEPT as allowed by the following statements: You may freely use* this file for your own work, including modifications and distribution* in compiled (class files, native executable, etc.) form only. You may* not copy and distribute this file. You may not remove this copyright* notice. You may not distribute modified versions of this source file.* You may not use this file in printed media without the express* permission of Bill Venners. ** BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE* SUITABILITY OF THIS SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS* FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT. BILL VENNERS SHALL NOT* BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A RESULT OF* USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.*/// On CD-ROM in file// linking/ex8/com/artima/greeter/GreeterClassLoader.javapackage com.artima.greeter;import java.io.*;import java.util.Hashtable;public class GreeterClassLoader extends ClassLoader {    // basePath gives the path to which this class    // loader appends "/<typename>.class" to get the    // full path name of the class file to load    private String basePath;    public GreeterClassLoader(String basePath) {        this.basePath = basePath;    }    public synchronized Class loadClass(String className,        boolean resolveIt) throws ClassNotFoundException {        Class result;        byte classData[];        // Check the loaded class cache        result = findLoadedClass(className);        if (result != null) {            // Return a cached class            return result;        }        // If Spoofed, don't delegate        if (className.compareTo("Spoofed") != 0) {            // Check with the system class loader            try {                result = super.findSystemClass(className);                // Return a system class                return result;            }            catch (ClassNotFoundException e) {            }        }        // Don't attempt to load a system file except through        // the primordial class loader        if (className.startsWith("java.")) {            throw new ClassNotFoundException();        }        // Try to load it from the basePath directory.        classData = getTypeFromBasePath(className);        if (classData == null) {            System.out.println("GCL - Can't load class: "                + className);            throw new ClassNotFoundException();        }        // Parse it        result = defineClass(className, classData, 0,            classData.length);        if (result == null) {            System.out.println("GCL - Class format error: "                + className);            throw new ClassFormatError();        }        if (resolveIt) {            resolveClass(result);        }        // Return class from basePath directory        return result;    }    private byte[] getTypeFromBasePath(String typeName) {        FileInputStream fis;        String fileName = basePath + File.separatorChar            + typeName.replace('.', File.separatorChar)            + ".class";        try {            fis = new FileInputStream(fileName);        }        catch (FileNotFoundException e) {            return null;        }        BufferedInputStream bis = new BufferedInputStream(fis);        ByteArrayOutputStream out = new ByteArrayOutputStream();        try {            int c = bis.read();            while (c != -1) {                out.write(c);                c = bis.read();            }        }        catch (IOException e) {            return null;        }        return out.toByteArray();    }}