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1   /*
2    * Copyright (c) 1999, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package sun.awt;
27  
28  /**
29    * The AWTSecurityManager class provides the ability to secondarily
30    * index AppContext objects through SecurityManager extensions.
31    * As noted in AppContext.java, AppContexts are primarily indexed by
32    * ThreadGroup.  In the case where the ThreadGroup doesn't provide
33    * enough information to determine AppContext (e.g. system threads),
34    * if a SecurityManager is installed which derives from
35    * AWTSecurityManager, the AWTSecurityManager's getAppContext()
36    * method is called to determine the AppContext.
37    *
38    * A typical example of the use of this class is where an applet
39    * is called by a system thread, yet the system AppContext is
40    * inappropriate, because applet code is currently executing.
41    * In this case, the getAppContext() method can walk the call stack
42    * to determine the applet code being executed and return the applet's
43    * AppContext object.
44    *
45    * @author  Fred Ecks
46    */
47  public class AWTSecurityManager extends SecurityManager {
48  
49      /**
50        * Get the AppContext corresponding to the current context.
51        * The default implementation returns null, but this method
52        * may be overridden by various SecurityManagers
53        * (e.g. AppletSecurity) to index AppContext objects by the
54        * calling context.
55        *
56        * @return  the AppContext corresponding to the current context.
57        * @see     sun.awt.AppContext
58        * @see     java.lang.SecurityManager
59        * @since   JDK1.2.1
60        */
61      public AppContext getAppContext() {
62          return null; // Default implementation returns null
63      }
64  
65  } /* class AWTSecurityManager */