    001// Copyright 2009, 2011 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007//     http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.ioc.internal.util;
    016
    017import java.util.concurrent.locks.Lock;
    018import java.util.concurrent.locks.ReentrantLock;
    019
    020/**
    021 * Internal utilities for identifying the JDK version, used in the rare cases
    022 * that we are patching around JDK bugs.
    023 */
    024public class JDKUtils
    025{
    026    /**
    027     * Is the running JVM JDK 1.5?
    028     */
    029    public static final boolean JDK_1_5 = isVersion("1.5");
    030
    031    private static boolean isVersion(String versionId)
    032    {
    033        return System.getProperty("java.specification.version").equals(versionId);
    034    }
    035
    036    /**
    037     * Returns a {@link ReentrantLock} used to serialize access to the construction of a thread local; this is only needed under JDK 1.5 (due to a bug in the JDK);
    038     * for other JDKs, a {@link DummyLock} is returned.
    039     *
    040     * @return lock to use when creating
    041     * @since 5.3
    042     * @deprecated Deprecated in 5.4 with no replacement.
    043     */
    044    public static Lock createLockForThreadLocalCreation()
    045    {
    046        return JDK_1_5 ? new ReentrantLock() : new DummyLock();
    047    }
    048}