Source for javax.management.AttributeValueExp

   1: /* AttributeValueExp.java -- Represents attributes to be passed to queries.
   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: /**
  41:  * Represents an attribute value being used as an argument
  42:  * to a relational constraint.
  43:  *
  44:  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  45:  * @since 1.5
  46:  */
  47: public class AttributeValueExp
  48:   implements ValueExp
  49: {
  50: 
  51:   /**
  52:    * Compatible with JDK 1.5
  53:    */
  54:   private static final long serialVersionUID = -7768025046539163385L;
  55: 
  56:   /**
  57:    * The name of the attribute.
  58:    */
  59:   private String attr;
  60: 
  61:   /**
  62:    * Constructs a new {@link AttributeValueExp}.
  63:    *
  64:    * @deprecated An instance created with a <code>null</code>
  65:    *             attribute name can not be used in a query.
  66:    */
  67:   @Deprecated public AttributeValueExp()
  68:   {
  69:   }
  70: 
  71:   /**
  72:    * Constructs a new {@link AttributeValueExp} using the
  73:    * specified attribute.
  74:    *
  75:    * @param attr the name of the attribute whose value
  76:    *             will be used for this expression.
  77:    */
  78:   public AttributeValueExp(String attr)
  79:   {
  80:     this.attr = attr;
  81:   }
  82: 
  83:   /**
  84:    * Applies the {@link AttributeValueExp} to the specified
  85:    * management bean by obtaining the attribute value from
  86:    * the {@link MBeanServer} and using it to create a
  87:    * {@link StringValueExp}.
  88:    *
  89:    * @param name the {@link ObjectName} of the bean to obtain
  90:    *             the value from.
  91:    * @return a {@link StringValueExp} containing the result.
  92:    * @throws BadStringOperationException if an invalid string
  93:    *                                     operation is used by
  94:    *                                     the value expression.
  95:    * @throws BadBinaryOpValueExpException if an invalid expression
  96:    *                                      is used by the value expression.
  97:    * @throws BadAttributeValueExpException if an invalid attribute
  98:    *                                       is used by the value expression.
  99:    * @throws InvalidApplicationException if the value expression is applied
 100:    *                                     to the wrong type of bean.
 101:    */
 102:   public ValueExp apply(ObjectName name)
 103:     throws BadStringOperationException, BadBinaryOpValueExpException,
 104:            BadAttributeValueExpException, InvalidApplicationException
 105:   {
 106:     Object val = getAttribute(name);
 107:     if (val == null || !(val instanceof String))
 108:       throw new BadAttributeValueExpException(val);
 109:     return new StringValueExp((String) val);
 110:   }
 111: 
 112:   /**
 113:    * Returns the value of the attribute by calling the
 114:    * {@link MBeanServer#getAttribute(ObjectName)} method of
 115:    * the server returned by {@link QueryEval#getMBeanServer()}.
 116:    * If an exception occurs, <code>null</code> is returned.
 117:    *
 118:    * @param name the {@link ObjectName} of the bean to obtain
 119:    *             the value from.
 120:    * @return a {@link StringValueExp} containing the result.
 121:    */
 122:   protected Object getAttribute(ObjectName name)
 123:   {
 124:     try
 125:       {
 126:         return QueryEval.getMBeanServer().getAttribute(name, attr);
 127:       }
 128:     catch (NullPointerException e)
 129:       {
 130:         return null;
 131:       }
 132:     catch (MBeanException e)
 133:       {
 134:         return null;
 135:       }
 136:     catch (AttributeNotFoundException e)
 137:       {
 138:         return null;
 139:       }
 140:     catch (InstanceNotFoundException e)
 141:       {
 142:         return null;
 143:       }
 144:     catch (ReflectionException e)
 145:       {
 146:         return null;
 147:       }
 148:   }
 149: 
 150:   /**
 151:    * Returns the attribute name.
 152:    *
 153:    * @return the attribute name.
 154:    */
 155:   public String getAttributeName()
 156:   {
 157:     return attr;
 158:   }
 159: 
 160:   /**
 161:    * Sets the {@link MBeanServer} on which the query
 162:    * will be performed.
 163:    *
 164:    * @param server the new server.
 165:    */
 166:   public void setMBeanServer(MBeanServer server)
 167:   {
 168:     /* This seems to do nothing any more */
 169:   }
 170: 
 171:   /**
 172:    * Returns the attribute name, quoted.
 173:    *
 174:    * @return the quoted attribute name.
 175:    */
 176:   public String toString()
 177:   {
 178:     return "'" + attr + "'";
 179:   }
 180: 
 181: }