J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1999-2004 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.management; |
| 27 | |
| 28 | |
| 29 | // RI import |
| 30 | import javax.management.MBeanServer; |
| 31 | |
| 32 | /** |
| 33 | * Represents attributes used as arguments to relational constraints. |
| 34 | * An <CODE>AttributeValueExp</CODE> may be used anywhere a <CODE>ValueExp</CODE> is required. |
| 35 | * |
| 36 | * @since 1.5 |
| 37 | */ |
| 38 | public class AttributeValueExp implements ValueExp { |
| 39 | |
| 40 | |
| 41 | /* Serial version */ |
| 42 | private static final long serialVersionUID = -7768025046539163385L; |
| 43 | |
| 44 | /** |
| 45 | * @serial The name of the attribute |
| 46 | */ |
| 47 | private String attr; |
| 48 | |
| 49 | /** |
| 50 | * An <code>AttributeValueExp</code> with a null attribute. |
| 51 | * @deprecated An instance created with this constructor cannot be |
| 52 | * used in a query. |
| 53 | */ |
| 54 | @Deprecated |
| 55 | public AttributeValueExp() { |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Creates a new <CODE>AttributeValueExp</CODE> representing the |
| 60 | * specified object attribute, named attr. |
| 61 | * |
| 62 | * @param attr the name of the attribute whose value is the value |
| 63 | * of this {@link ValueExp}. |
| 64 | */ |
| 65 | public AttributeValueExp(String attr) { |
| 66 | this.attr = attr; |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Returns a string representation of the name of the attribute. |
| 71 | * |
| 72 | * @return the attribute name. |
| 73 | */ |
| 74 | public String getAttributeName() { |
| 75 | return attr; |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Applies the <CODE>AttributeValueExp</CODE> on an MBean. |
| 80 | * |
| 81 | * @param name The name of the MBean on which the <CODE>AttributeValueExp</CODE> will be applied. |
| 82 | * |
| 83 | * @return The <CODE>ValueExp</CODE>. |
| 84 | * |
| 85 | * @exception BadAttributeValueExpException |
| 86 | * @exception InvalidApplicationException |
| 87 | * @exception BadStringOperationException |
| 88 | * @exception BadBinaryOpValueExpException |
| 89 | * |
| 90 | */ |
| 91 | public ValueExp apply(ObjectName name) throws BadStringOperationException, BadBinaryOpValueExpException, |
| 92 | BadAttributeValueExpException, InvalidApplicationException { |
| 93 | Object result = getAttribute(name); |
| 94 | |
| 95 | if (result instanceof Number) { |
| 96 | return new NumericValueExp((Number)result); |
| 97 | } else if (result instanceof String) { |
| 98 | return new StringValueExp((String)result); |
| 99 | } else if (result instanceof Boolean) { |
| 100 | return new BooleanValueExp((Boolean)result); |
| 101 | } else { |
| 102 | throw new BadAttributeValueExpException(result); |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * Returns the string representing its value. |
| 108 | */ |
| 109 | public String toString() { |
| 110 | return attr; |
| 111 | } |
| 112 | |
| 113 | |
| 114 | /** |
| 115 | * Sets the MBean server on which the query is to be performed. |
| 116 | * |
| 117 | * @param s The MBean server on which the query is to be performed. |
| 118 | */ |
| 119 | /* There is no need for this method, because if a query is being |
| 120 | evaluted an AttributeValueExp can only appear inside a QueryExp, |
| 121 | and that QueryExp will itself have done setMBeanServer. */ |
| 122 | public void setMBeanServer(MBeanServer s) { |
| 123 | } |
| 124 | |
| 125 | |
| 126 | /** |
| 127 | * Return the value of the given attribute in the named MBean. |
| 128 | * If the attempt to access the attribute generates an exception, |
| 129 | * return null. |
| 130 | * |
| 131 | * @param name the name of the MBean whose attribute is to be returned. |
| 132 | * |
| 133 | * @return the value of the attribute, or null if it could not be |
| 134 | * obtained. |
| 135 | */ |
| 136 | protected Object getAttribute(ObjectName name) { |
| 137 | try { |
| 138 | // Get the value from the MBeanServer |
| 139 | |
| 140 | MBeanServer server = QueryEval.getMBeanServer(); |
| 141 | |
| 142 | return server.getAttribute(name, attr); |
| 143 | } catch (Exception re) { |
| 144 | return null; |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | } |