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 */ AttributeValueExp()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 */ AttributeValueExp(String attr)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 */ apply(ObjectName name)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 */ getAttribute(ObjectName name)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 */ getAttributeName()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 */ setMBeanServer(MBeanServer server)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 */ toString()176 public String toString() 177 { 178 return "'" + attr + "'"; 179 } 180 181 } 182