libjava/classpath/javax/management/Notification.java

   1 /* Notification.java -- A notification emitted by a bean.
   2    Copyright (C) 2006 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.IOException;
  41 import java.io.ObjectOutputStream;
  42
  43 import java.util.Date;
  44 import java.util.EventObject;
  45
  46 /**
  47  * <p>
  48  * A notification message that may be emitted by a bean.
  49  * Notifications have both a message and a type, so individual
  50  * notifications can be grouped by type.  They also incorporate
  51  * sequencing, so that the recipient can order the delivered
  52  * messages correctly (there is no guarantee that they will
  53  * be delivered in order).
  54  * </p>
  55  * <p>
  56  * Notifications also include a reference to the source of
  57  * the notification.  The source bean is represented either
  58  * by an {@link ObjectName} or by a direct reference to the
  59  * bean.  The former is preferable, and notifications emitted
  60  * via a {@link MBeanServer} will automatically have the source
  61  * transformed into an {@link ObjectName}.
  62  * </p>
  63  *
  64  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  65  * @since 1.5
  66  */
  67 public class Notification
  68   extends EventObject
  69 {
  70
  71   /**
  72    * Compatible with JDK 1.6
  73    */
  74   private static final long serialVersionUID = -7516092053498031989L;
  75
  76   /**
  77    * The notification message.
  78    *
  79    * @serial the notification message.
  80    */
  81   private String message;
  82
  83   /**
  84    * The notification's sequence number, relative to the notifications
  85    * emitted by the bean.
  86    *
  87    * @serial the notification sequence number.
  88    */
  89   private long sequenceNumber;
  90
  91   /**
  92    * The source of the notification.  This is redeclared in order to
  93    * replace the <code>source</code> variable in {@link java.util.EventObject}
  94    * with a non-transient version.
  95    *
  96    * @serial the notification source.
  97    */
  98   protected Object source;
  99
 100   /**
 101    * The time the notification was generated.
 102    *
 103    * @serial the notification timestamp.
 104    */
 105   private long timeStamp;
 106
 107   /**
 108    * The type of notification sent.  This utilises the same style
 109    * as Java property and package names.  For example,
 110    * <code>gnu.gcj.compiler</code> may be one type of notifications.
 111    *
 112    * @serial the notification type.
 113    */
 114   private String type;
 115
 116   /**
 117    * The user data associated with the notification.  This includes
 118    * any additional data which should be transmitted with the notification,
 119    * but can't be achieved using the {@link java.lang.String} format
 120    * of the <code>message</code>.
 121    *
 122    * @serial the notification user data.
 123    */
 124   private Object userData;
 125
 126   /**
 127    * Creates a new {@link Notification} object with the specified type,
 128    * source and sequence number.  The timestamp is created using the
 129    * current date and time.
 130    *
 131    * @param type the type of the notification.
 132    * @param source the source of the notification.
 133    * @param sequenceNumber the sequence number of the notifcation.
 134    */
 135   public Notification(String type, Object source, long sequenceNumber)
 136   {
 137     this(type, source, sequenceNumber, new Date().getTime());
 138   }
 139
 140   /**
 141    * Creates a new {@link Notification} object with the specified type,
 142    * source, sequence number and timestamp.
 143    *
 144    * @param type the type of the notification.
 145    * @param source the source of the notification.
 146    * @param sequenceNumber the sequence number of the notifcation.
 147    * @param timeStamp the time the notification was emitted.
 148    */
 149   public Notification(String type, Object source, long sequenceNumber,
 150                       long timeStamp)
 151   {
 152     this(type, source, sequenceNumber, timeStamp, "");
 153   }
 154
 155   /**
 156    * Creates a new {@link Notification} object with the specified type,
 157    * source, sequence number, timestamp and message.
 158    *
 159    * @param type the type of the notification.
 160    * @param source the source of the notification.
 161    * @param sequenceNumber the sequence number of the notifcation.
 162    * @param timeStamp the time the notification was emitted.
 163    * @param message the message contained in the notification.
 164    */
 165   public Notification(String type, Object source, long sequenceNumber,
 166                       long timeStamp, String message)
 167   {
 168     super(source);
 169     this.type = type;
 170     this.source = source;
 171     this.sequenceNumber = sequenceNumber;
 172     this.timeStamp = timeStamp;
 173     this.message = message;
 174   }
 175
 176   /**
 177    * Creates a new {@link Notification} object with the specified type,
 178    * source, sequence number and message.  The timestamp is created using
 179    * the current date and time.
 180    *
 181    * @param type the type of the notification.
 182    * @param source the source of the notification.
 183    * @param sequenceNumber the sequence number of the notifcation.
 184    * @param message the message contained in the notification.
 185    */
 186   public Notification(String type, Object source, long sequenceNumber,
 187                       String message)
 188   {
 189     this(type, source, sequenceNumber, new Date().getTime(), message);
 190   }
 191
 192   /**
 193    * Returns the message contained in this notification.  The message
 194    * is in {@link java.lang.String} form, and is thus intended for
 195    * display to the end-user.  Data transferred as part of the notification
 196    * which shouldn't be displayed is included in the <code>userData</code>
 197    * field.
 198    *
 199    * @return the notification message.
 200    * @see #getUserData()
 201    * @see #setUserData(java.lang.Object)
 202    */
 203   public String getMessage()
 204   {
 205     return message;
 206   }
 207
 208   /**
 209    * Returns the sequence number of this notification.  This
 210    * can be used to determine the order in which notifications
 211    * were emitted by the broadcasting bean.
 212    *
 213    * @return the sequence number.
 214    * @see #setSequenceNumber(long)
 215    */
 216   public long getSequenceNumber()
 217   {
 218     return sequenceNumber;
 219   }
 220
 221   /**
 222    * Returns the date and time at which this notification was
 223    * emitted.
 224    *
 225    * @return the notification timestamp.
 226    * @see #setTimeStamp(long)
 227    */
 228   public long getTimeStamp()
 229   {
 230     return timeStamp;
 231   }
 232
 233   /**
 234    * Returns the type of this notification.  Types take the same
 235    * form as Java package and property names.
 236    *
 237    * @return the type of the notification.
 238    */
 239   public String getType()
 240   {
 241     return type;
 242   }
 243
 244   /**
 245    * Returns the additional user data associated with the notification.
 246    * This is used to attach additional non-textual information to the
 247    * notification.
 248    *
 249    * @return the user data associated with the notification.
 250    * @see #setUserData(java.lang.Object)
 251    */
 252   public Object getUserData()
 253   {
 254     return userData;
 255   }
 256
 257   /**
 258    * Sets the sequence number to the value specified.
 259    *
 260    * @param sequenceNumber the new sequence number.
 261    * @see #getSequenceNumber()
 262    */
 263   public void setSequenceNumber(long sequenceNumber)
 264   {
 265     this.sequenceNumber = sequenceNumber;
 266   }
 267
 268   /**
 269    * Sets the source of this notification to the value
 270    * specified.
 271    *
 272    * @param source the new source of the notification.
 273    * @see java.util.EventSource#getSource()
 274    */
 275   public void setSource(Object source)
 276   {
 277     this.source = source;
 278   }
 279
 280   /**
 281    * Sets the date and time at which this notification
 282    * was emitted.
 283    *
 284    * @param timeStamp the new time stamp of the notification.
 285    * @see #getTimeStamp()
 286    */
 287   public void setTimeStamp(long timeStamp)
 288   {
 289     this.timeStamp = timeStamp;
 290   }
 291
 292   /**
 293    * Sets the additional user data associated with the notification
 294    * to the specified value.  This is used to attach additional
 295    * non-textual information to the notification.
 296    *
 297    * @param userData the new user data associated with the notification.
 298    * @see #getUserData()
 299    */
 300   public void setUserData(Object userData)
 301   {
 302     this.userData = userData;
 303   }
 304
 305   /**
 306    * A textual representation of the notification.
 307    *
 308    * @return the notification in {@link java.lang.String} form.
 309    */
 310   public String toString()
 311   {
 312     return getClass().getName()
 313       + "[message=" + message
 314       + ", sequenceNumber=" + sequenceNumber
 315       + ", source=" + source
 316       + ", timeStamp=" + timeStamp
 317       + ", type=" + type
 318       + ", userData=" + userData
 319       + "]";
 320   }
 321
 322   /**
 323    * Serialize the {@link Notification}.
 324    *
 325    * @param out the output stream to write to.
 326    * @throws IOException if an I/O error occurs.
 327    */
 328   private void writeObject(ObjectOutputStream out)
 329     throws IOException
 330   {
 331     out.defaultWriteObject();
 332   }
 333
 334 }