/*

 * Copyright (c) 1999, 2011, 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);

}