我安装了最新的 JDK (1.7.0_21)。当我在 Eclipse 中查看基础类的源代码时，例如java.lang.String文件顶部的许可证显示：
/*
* Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
此源代码来自src.zipJDK 版本附带的文件。
当我在这里查看源代码时：http: //grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/7-b147/java/lang/String.java ?av=f
...我看到了 GPL v2.0 许可标头。
/*
* Copyright (c) 1994, 2010, 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.
*/
据我了解，JDK 1.7 是作为完全开源发布的，在 GPL 2.0 下获得许可。
有人可以解释许可证差异吗？