Source for javax.management.QueryEval

   1: /* QueryEval.java -- An evaluation context for a MBean server query.
   2:    Copyright (C) 2007 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package javax.management;
  39: 
  40: import java.io.Serializable;
  41: 
  42: /**
  43:  * Represents the evaluation context of a {@link MBeanServer}
  44:  * query by retaining the server used on a thread-by-thread
  45:  * basis.
  46:  *
  47:  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  48:  * @since 1.5
  49:  */
  50: public class QueryEval
  51:   implements Serializable
  52: {
  53: 
  54:   /**
  55:    * Compatible with JDK 1.5
  56:    */
  57:   private static final long serialVersionUID = 2675899265640874796L;
  58: 
  59:   /**
  60:    * Stores the server used, on a 
  61:    * thread-by-thread basis.
  62:    */
  63:   private static InheritableThreadLocal<MBeanServer> server =
  64:     new InheritableThreadLocal<MBeanServer>();
  65: 
  66:   /**
  67:    * Returns the {@link MBeanServer} last supplied to the
  68:    * {@link #setMBeanServer(MBeanServer)} method.  If this method
  69:    * has not been called for this thread, then the value will be
  70:    * inherited from any parent thread on which the method has
  71:    * been called.  If the method has never been called, then
  72:    * <code>null</code> is returned.
  73:    *
  74:    * @return the server.
  75:    * @see #setMBeanServer(MBeanServer)
  76:    */
  77:   public static MBeanServer getMBeanServer()
  78:   {
  79:     return server.get();
  80:   }
  81: 
  82:   /**
  83:    * Sets the {@link MBeanServer} on which the query will be
  84:    * performed.  This value is inherited automatically by
  85:    * child threads.  This method is only non-static for historical
  86:    * reasons; it makes no use of instance-related values. 
  87:    *
  88:    * @param svr the server to use.
  89:    */
  90:   public void setMBeanServer(MBeanServer svr)
  91:   {
  92:     server.set(svr);
  93:   }
  94: 
  95: }