JDK8/Java8源码在线阅读

/*
 * Copyright (c) 1999, 2013, 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.URLClassLoader;
import java.net.MalformedURLException;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import sun.misc.SharedSecrets;

final class VersionHelper12 extends VersionHelper {

    // System property to control whether classes may be loaded from an
    // arbitrary URL code base.
    private static final String TRUST_URL_CODEBASE_PROPERTY =
        "com.sun.jndi.ldap.object.trustURLCodebase";

    // Determine whether classes may be loaded from an arbitrary URL code base.
    private static final String trustURLCodebase =
        AccessController.doPrivileged(
            new PrivilegedAction<String>() {
                public String run() {
                    return System.getProperty(TRUST_URL_CODEBASE_PROPERTY,
                            "false");
                }
            }
        );

    VersionHelper12() {} // Disallow external from creating one of these.

    ClassLoader getURLClassLoader(String[] url)
        throws MalformedURLException {
            ClassLoader parent = getContextClassLoader();
            /*
             * Classes may only be loaded from an arbitrary URL code base when
             * the system property com.sun.jndi.ldap.object.trustURLCodebase
             * has been set to "true".
             */
            if (url != null && "true".equalsIgnoreCase(trustURLCodebase)) {
                return URLClassLoader.newInstance(getUrlArray(url), parent);
            } else {
                return parent;
            }
    }

    Class<?> loadClass(String className) throws ClassNotFoundException {
        ClassLoader cl = getContextClassLoader();
        return Class.forName(className, true, cl);
    }

    private ClassLoader getContextClassLoader() {
        return AccessController.doPrivileged(
            new PrivilegedAction<ClassLoader>() {
                public ClassLoader run() {
                    return Thread.currentThread().getContextClassLoader();
                }
            }
        );
    }

    Thread createThread(final Runnable r) {
        final AccessControlContext acc = AccessController.getContext();

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