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   1.2.1
  60       */
  61     public AppContext getAppContext() {
  62         return null; // Default implementation returns null
  63     }
  64 
  65 } /* class AWTSecurityManager */