/* * Copyright (c) 1999, 2008, 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 javax.management; // java importimport java.io.Serializable; /** * Allows a query to be performed in the context of a specific MBean server. * * @since 1.5 */public abstract class QueryEval implements Serializable {     /* Serial version */    private static final long serialVersionUID = 2675899265640874796L;     private static ThreadLocal<MBeanServer> server =        new InheritableThreadLocal<MBeanServer>();     /**     * <p>Sets the MBean server on which the query is to be performed.     * The setting is valid for the thread performing the set.     * It is copied to any threads created by that thread at the moment     * of their creation.</p>     *     * <p>For historical reasons, this method is not static, but its     * behavior does not depend on the instance on which it is     * called.</p>     *     * @param s The MBean server on which the query is to be performed.     *     * @see #getMBeanServer     */    public void setMBeanServer(MBeanServer s) {        server.set(s);    }     /**     * <p>Return the MBean server that was most recently given to the     * {@link #setMBeanServer setMBeanServer} method by this thread.     * If this thread never called that method, the result is the     * value its parent thread would have obtained from     * <code>getMBeanServer</code> at the moment of the creation of     * this thread, or null if there is no parent thread.</p>     *     * @return the MBean server.     *     * @see #setMBeanServer     *     */    public static MBeanServer getMBeanServer() {        return server.get();    }}