/* * Copyright (c) 1999, 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.jndi.ldap; import java.net.MalformedURLException;import java.net.URL; abstract class VersionHelper {     private static VersionHelper helper = null;     VersionHelper() {} // Disallow anyone from creating one of these.     static {        try {            Class.forName("java.net.URLClassLoader"); // 1.2 test            Class.forName("java.security.PrivilegedAction"); // 1.2 test            helper = (VersionHelper)                Class.forName(                    "com.sun.jndi.ldap.VersionHelper12").newInstance();        } catch (Exception e) {        }         // Use 1.1 helper if 1.2 test fails, or if we cannot create 1.2 helper        if (helper == null) {            try {                helper = (VersionHelper)                    Class.forName(                        "com.sun.jndi.ldap.VersionHelper11").newInstance();            } catch (Exception e) {                // should never happen            }        }    }     static VersionHelper getVersionHelper() {        return helper;    }     abstract ClassLoader getURLClassLoader(String[] url)        throws MalformedURLException;      static protected URL[] getUrlArray(String[] url) throws MalformedURLException {        URL[] urlArray = new URL[url.length];        for (int i = 0; i < urlArray.length; i++) {            urlArray[i] = new URL(url[i]);        }        return urlArray;    }     abstract Class loadClass(String className) throws ClassNotFoundException;     abstract Thread createThread(Runnable r);}