/* * Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package com.sun.naming.internal; import java.io.InputStream;import java.io.IOException;import java.net.MalformedURLException;import java.net.URL;import java.util.Enumeration;import java.util.StringTokenizer;import java.util.Vector; import javax.naming.NamingEnumeration; /** * VersionHelper was used by JNDI to accommodate differences between * JDK 1.1.x and the Java 2 platform. As this is no longer necessary * since JNDI's inclusion in the platform, this class currently * serves as a set of utilities for performing system-level things, * such as class-loading and reading system properties. * * @author Rosanna Lee * @author Scott Seligman */ public abstract class VersionHelper {    private static VersionHelper helper = null;     final static String[] PROPS = new String[] {        javax.naming.Context.INITIAL_CONTEXT_FACTORY,        javax.naming.Context.OBJECT_FACTORIES,        javax.naming.Context.URL_PKG_PREFIXES,        javax.naming.Context.STATE_FACTORIES,        javax.naming.Context.PROVIDER_URL,        javax.naming.Context.DNS_URL,        // The following shouldn't create a runtime dependence on ldap package.        javax.naming.ldap.LdapContext.CONTROL_FACTORIES    };     public final static int INITIAL_CONTEXT_FACTORY = 0;    public final static int OBJECT_FACTORIES = 1;    public final static int URL_PKG_PREFIXES = 2;    public final static int STATE_FACTORIES = 3;    public final static int PROVIDER_URL = 4;    public final static int DNS_URL = 5;    public final static int CONTROL_FACTORIES = 6;     VersionHelper() {} // Disallow anyone from creating one of these.     static {        helper = new VersionHelper12();    }     public static VersionHelper getVersionHelper() {        return helper;    }     public abstract Class loadClass(String className)        throws ClassNotFoundException;     abstract Class loadClass(String className, ClassLoader cl)        throws ClassNotFoundException;     public abstract Class loadClass(String className, String codebase)        throws ClassNotFoundException, MalformedURLException;     /*     * Returns a JNDI property from the system properties.  Returns     * null if the property is not set, or if there is no permission     * to read it.     */    abstract String getJndiProperty(int i);     /*     * Reads each property in PROPS from the system properties, and     * returns their values -- in order -- in an array.  For each     * unset property, the corresponding array element is set to null.     * Returns null if there is no permission to call System.getProperties().     */    abstract String[] getJndiProperties();     /*     * Returns the resource of a given name associated with a particular     * class (never null), or null if none can be found.     */    abstract InputStream getResourceAsStream(Class c, String name);     /*     * Returns an input stream for a file in <java.home>/lib,     * or null if it cannot be located or opened.     *     * @param filename  The file name, sans directory.     */    abstract InputStream getJavaHomeLibStream(String filename);     /*     * Returns an enumeration (never null) of InputStreams of the     * resources of a given name associated with a particular class     * loader.  Null represents the bootstrap class loader in some     * Java implementations.     */    abstract NamingEnumeration getResources(ClassLoader cl, String name)        throws IOException;     /*     * Returns the context class loader associated with the current thread.     * Null indicates the bootstrap class loader in some Java implementations.     *     * @throws SecurityException if the class loader is not accessible.     */    abstract ClassLoader getContextClassLoader();     static protected URL[] getUrlArray(String codebase)        throws MalformedURLException {        // Parse codebase into separate URLs        StringTokenizer parser = new StringTokenizer(codebase);        Vector vec = new Vector(10);        while (parser.hasMoreTokens()) {            vec.addElement(parser.nextToken());        }        String[] url = new String[vec.size()];        for (int i = 0; i < url.length; i++) {            url[i] = (String)vec.elementAt(i);        }         URL[] urlArray = new URL[url.length];        for (int i = 0; i < urlArray.length; i++) {            urlArray[i] = new URL(url[i]);        }        return urlArray;    }}