J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1999-2006 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 | import java.io.IOException; |
| 29 | import java.io.ObjectInputStream; |
| 30 | import java.io.ObjectOutputStream; |
| 31 | import java.io.Serializable; |
| 32 | import java.io.StreamCorruptedException; |
| 33 | |
| 34 | /** |
| 35 | * <p>Provides general information for an MBean descriptor object. |
| 36 | * The feature described can be an attribute, an operation, a |
| 37 | * parameter, or a notification. Instances of this class are |
| 38 | * immutable. Subclasses may be mutable but this is not |
| 39 | * recommended.</p> |
| 40 | * |
| 41 | * @since 1.5 |
| 42 | */ |
| 43 | public class MBeanFeatureInfo implements Serializable, DescriptorRead { |
| 44 | |
| 45 | |
| 46 | /* Serial version */ |
| 47 | static final long serialVersionUID = 3952882688968447265L; |
| 48 | |
| 49 | /** |
| 50 | * The name of the feature. It is recommended that subclasses call |
| 51 | * {@link #getName} rather than reading this field, and that they |
| 52 | * not change it. |
| 53 | * |
| 54 | * @serial The name of the feature. |
| 55 | */ |
| 56 | protected String name; |
| 57 | |
| 58 | /** |
| 59 | * The human-readable description of the feature. It is |
| 60 | * recommended that subclasses call {@link #getDescription} rather |
| 61 | * than reading this field, and that they not change it. |
| 62 | * |
| 63 | * @serial The human-readable description of the feature. |
| 64 | */ |
| 65 | protected String description; |
| 66 | |
| 67 | /** |
| 68 | * @serial The Descriptor for this MBeanFeatureInfo. This field |
| 69 | * can be null, which is equivalent to an empty Descriptor. |
| 70 | */ |
| 71 | private transient Descriptor descriptor; |
| 72 | |
| 73 | |
| 74 | /** |
| 75 | * Constructs an <CODE>MBeanFeatureInfo</CODE> object. This |
| 76 | * constructor is equivalent to {@code MBeanFeatureInfo(name, |
| 77 | * description, (Descriptor) null}. |
| 78 | * |
| 79 | * @param name The name of the feature. |
| 80 | * @param description A human readable description of the feature. |
| 81 | */ |
| 82 | public MBeanFeatureInfo(String name, String description) { |
| 83 | this(name, description, null); |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Constructs an <CODE>MBeanFeatureInfo</CODE> object. |
| 88 | * |
| 89 | * @param name The name of the feature. |
| 90 | * @param description A human readable description of the feature. |
| 91 | * @param descriptor The descriptor for the feature. This may be null |
| 92 | * which is equivalent to an empty descriptor. |
| 93 | * |
| 94 | * @since 1.6 |
| 95 | */ |
| 96 | public MBeanFeatureInfo(String name, String description, |
| 97 | Descriptor descriptor) { |
| 98 | this.name = name; |
| 99 | this.description = description; |
| 100 | this.descriptor = descriptor; |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * Returns the name of the feature. |
| 105 | * |
| 106 | * @return the name of the feature. |
| 107 | */ |
| 108 | public String getName() { |
| 109 | return name; |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Returns the human-readable description of the feature. |
| 114 | * |
| 115 | * @return the human-readable description of the feature. |
| 116 | */ |
| 117 | public String getDescription() { |
| 118 | return description; |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Returns the descriptor for the feature. Changing the returned value |
| 123 | * will have no affect on the original descriptor. |
| 124 | * |
| 125 | * @return a descriptor that is either immutable or a copy of the original. |
| 126 | * |
| 127 | * @since 1.6 |
| 128 | */ |
| 129 | public Descriptor getDescriptor() { |
| 130 | return (Descriptor) ImmutableDescriptor.nonNullDescriptor(descriptor).clone(); |
| 131 | } |
| 132 | |
| 133 | /** |
| 134 | * Compare this MBeanFeatureInfo to another. |
| 135 | * |
| 136 | * @param o the object to compare to. |
| 137 | * |
| 138 | * @return true if and only if <code>o</code> is an MBeanFeatureInfo such |
| 139 | * that its {@link #getName()}, {@link #getDescription()}, and |
| 140 | * {@link #getDescriptor()} |
| 141 | * values are equal (not necessarily identical) to those of this |
| 142 | * MBeanFeatureInfo. |
| 143 | */ |
| 144 | public boolean equals(Object o) { |
| 145 | if (o == this) |
| 146 | return true; |
| 147 | if (!(o instanceof MBeanFeatureInfo)) |
| 148 | return false; |
| 149 | MBeanFeatureInfo p = (MBeanFeatureInfo) o; |
| 150 | return (p.getName().equals(getName()) && |
| 151 | p.getDescription().equals(getDescription()) && |
| 152 | p.getDescriptor().equals(getDescriptor())); |
| 153 | } |
| 154 | |
| 155 | public int hashCode() { |
| 156 | return getName().hashCode() ^ getDescription().hashCode() ^ |
| 157 | getDescriptor().hashCode(); |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Serializes an {@link MBeanFeatureInfo} to an {@link ObjectOutputStream}. |
| 162 | * @serialData |
| 163 | * For compatibility reasons, an object of this class is serialized as follows. |
| 164 | * <ul> |
| 165 | * The method {@link ObjectOutputStream#defaultWriteObject defaultWriteObject()} |
| 166 | * is called first to serialize the object except the field {@code descriptor} |
| 167 | * which is declared as transient. The field {@code descriptor} is serialized |
| 168 | * as follows: |
| 169 | * <ul> |
| 170 | * <li>If {@code descriptor} is an instance of the class |
| 171 | * {@link ImmutableDescriptor}, the method {@link ObjectOutputStream#write |
| 172 | * write(int val)} is called to write a byte with the value {@code 1}, |
| 173 | * then the method {@link ObjectOutputStream#writeObject writeObject(Object obj)} |
| 174 | * is called twice to serialize the field names and the field values of the |
| 175 | * {@code descriptor}, respectively as a {@code String[]} and an |
| 176 | * {@code Object[]};</li> |
| 177 | * <li>Otherwise, the method {@link ObjectOutputStream#write write(int val)} |
| 178 | * is called to write a byte with the value {@code 0}, then the method |
| 179 | * {@link ObjectOutputStream#writeObject writeObject(Object obj)} is called |
| 180 | * to serialize directly the field {@code descriptor}. |
| 181 | * </ul> |
| 182 | * </ul> |
| 183 | * @since 1.6 |
| 184 | */ |
| 185 | private void writeObject(ObjectOutputStream out) throws IOException { |
| 186 | out.defaultWriteObject(); |
| 187 | |
| 188 | if (descriptor != null && |
| 189 | descriptor.getClass() == ImmutableDescriptor.class) { |
| 190 | |
| 191 | out.write(1); |
| 192 | |
| 193 | final String[] names = descriptor.getFieldNames(); |
| 194 | |
| 195 | out.writeObject(names); |
| 196 | out.writeObject(descriptor.getFieldValues(names)); |
| 197 | } else { |
| 198 | out.write(0); |
| 199 | |
| 200 | out.writeObject(descriptor); |
| 201 | } |
| 202 | } |
| 203 | |
| 204 | /** |
| 205 | * Deserializes an {@link MBeanFeatureInfo} from an {@link ObjectInputStream}. |
| 206 | * @serialData |
| 207 | * For compatibility reasons, an object of this class is deserialized as follows. |
| 208 | * <ul> |
| 209 | * The method {@link ObjectInputStream#defaultReadObject defaultReadObject()} |
| 210 | * is called first to deserialize the object except the field |
| 211 | * {@code descriptor}, which is not serialized in the default way. Then the method |
| 212 | * {@link ObjectInputStream#read read()} is called to read a byte, the field |
| 213 | * {@code descriptor} is deserialized according to the value of the byte value: |
| 214 | * <ul> |
| 215 | * <li>1. The method {@link ObjectInputStream#readObject readObject()} |
| 216 | * is called twice to obtain the field names (a {@code String[]}) and |
| 217 | * the field values (a {@code Object[]}) of the {@code descriptor}. |
| 218 | * The two obtained values then are used to construct |
| 219 | * an {@link ImmutableDescriptor} instance for the field |
| 220 | * {@code descriptor};</li> |
| 221 | * <li>0. The value for the field {@code descriptor} is obtained directly |
| 222 | * by calling the method {@link ObjectInputStream#readObject readObject()}. |
| 223 | * If the obtained value is null, the field {@code descriptor} is set to |
| 224 | * {@link ImmutableDescriptor#EMPTY_DESCRIPTOR EMPTY_DESCRIPTOR};</li> |
| 225 | * <li>-1. This means that there is no byte to read and that the object is from |
| 226 | * an earlier version of the JMX API. The field {@code descriptor} is set |
| 227 | * to {@link ImmutableDescriptor#EMPTY_DESCRIPTOR EMPTY_DESCRIPTOR}</li> |
| 228 | * <li>Any other value. A {@link StreamCorruptedException} is thrown.</li> |
| 229 | * </ul> |
| 230 | * </ul> |
| 231 | * @since 1.6 |
| 232 | */ |
| 233 | private void readObject(ObjectInputStream in) |
| 234 | throws IOException, ClassNotFoundException { |
| 235 | |
| 236 | in.defaultReadObject(); |
| 237 | |
| 238 | switch (in.read()) { |
| 239 | case 1: |
| 240 | final String[] names = (String[])in.readObject(); |
| 241 | |
| 242 | if (names.length == 0) { |
| 243 | descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR; |
| 244 | } else { |
| 245 | final Object[] values = (Object[])in.readObject(); |
| 246 | descriptor = new ImmutableDescriptor(names, values); |
| 247 | } |
| 248 | |
| 249 | break; |
| 250 | case 0: |
| 251 | descriptor = (Descriptor)in.readObject(); |
| 252 | |
| 253 | if (descriptor == null) { |
| 254 | descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR; |
| 255 | } |
| 256 | |
| 257 | break; |
| 258 | case -1: // from an earlier version of the JMX API |
| 259 | descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR; |
| 260 | |
| 261 | break; |
| 262 | default: |
| 263 | throw new StreamCorruptedException("Got unexpected byte."); |
| 264 | } |
| 265 | } |
| 266 | } |