Java tutorial
/* * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.management; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.ObjectStreamField; import java.util.EventObject; import java.security.AccessController; import com.sun.jmx.mbeanserver.GetPropertyAction; /** * <p>The Notification class represents a notification emitted by an * MBean. It contains a reference to the source MBean: if the * notification has been forwarded through the MBean server, and the * original source of the notification was a reference to the emitting * MBean object, then the MBean server replaces it by the MBean's * ObjectName. If the listener has registered directly with the * MBean, this is either the object name or a direct reference to the * MBean.</p> * * <p>It is strongly recommended that notification senders use the * object name rather than a reference to the MBean object as the * source.</p> * * <p>The <b>serialVersionUID</b> of this class is <code>-7516092053498031989L</code>. * * @since 1.5 */ @SuppressWarnings("serial") // serialVersionUID is not constant public class Notification extends EventObject { // Serialization compatibility stuff: // Two serial forms are supported in this class. The selected form depends // on system property "jmx.serial.form": // - "1.0" for JMX 1.0 // - any other value for JMX 1.1 and higher // // Serial version for old serial form private static final long oldSerialVersionUID = 1716977971058914352L; // // Serial version for new serial form private static final long newSerialVersionUID = -7516092053498031989L; // // Serializable fields in old serial form private static final ObjectStreamField[] oldSerialPersistentFields = { new ObjectStreamField("message", String.class), new ObjectStreamField("sequenceNumber", Long.TYPE), new ObjectStreamField("source", Object.class), new ObjectStreamField("sourceObjectName", ObjectName.class), new ObjectStreamField("timeStamp", Long.TYPE), new ObjectStreamField("type", String.class), new ObjectStreamField("userData", Object.class) }; // // Serializable fields in new serial form private static final ObjectStreamField[] newSerialPersistentFields = { new ObjectStreamField("message", String.class), new ObjectStreamField("sequenceNumber", Long.TYPE), new ObjectStreamField("source", Object.class), new ObjectStreamField("timeStamp", Long.TYPE), new ObjectStreamField("type", String.class), new ObjectStreamField("userData", Object.class) }; // // Actual serial version and serial form private static final long serialVersionUID; /** * @serialField type String The notification type. * A string expressed in a dot notation similar to Java properties. * An example of a notification type is network.alarm.router * @serialField sequenceNumber long The notification sequence number. * A serial number which identify particular instance * of notification in the context of the notification source. * @serialField timeStamp long The notification timestamp. * Indicating when the notification was generated * @serialField userData Object The notification user data. * Used for whatever other data the notification * source wishes to communicate to its consumers * @serialField message String The notification message. * @serialField source Object The object on which the notification initially occurred. */ private static final ObjectStreamField[] serialPersistentFields; private static boolean compat = false; static { try { GetPropertyAction act = new GetPropertyAction("jmx.serial.form"); String form = AccessController.doPrivileged(act); compat = (form != null && form.equals("1.0")); } catch (Exception e) { // OK: exception means no compat with 1.0, too bad } if (compat) { serialPersistentFields = oldSerialPersistentFields; serialVersionUID = oldSerialVersionUID; } else { serialPersistentFields = newSerialPersistentFields; serialVersionUID = newSerialVersionUID; } } // // END Serialization compatibility stuff /** * @serial The notification type. * A string expressed in a dot notation similar to Java properties. * An example of a notification type is network.alarm.router */ private String type; /** * @serial The notification sequence number. * A serial number which identify particular instance * of notification in the context of the notification source. */ private long sequenceNumber; /** * @serial The notification timestamp. * Indicating when the notification was generated */ private long timeStamp; /** * @serial The notification user data. * Used for whatever other data the notification * source wishes to communicate to its consumers */ private Object userData = null; /** * @serial The notification message. */ private String message = ""; /** * <p>This field hides the {@link EventObject#source} field in the * parent class to make it non-transient and therefore part of the * serialized form.</p> * * @serial The object on which the notification initially occurred. */ protected Object source = null; /** * Creates a Notification object. * The notification timeStamp is set to the current date. * * @param type The notification type. * @param source The notification source. * @param sequenceNumber The notification sequence number within the source object. * */ public Notification(String type, Object source, long sequenceNumber) { super(source); this.source = source; this.type = type; this.sequenceNumber = sequenceNumber; this.timeStamp = (new java.util.Date()).getTime(); } /** * Creates a Notification object. * The notification timeStamp is set to the current date. * * @param type The notification type. * @param source The notification source. * @param sequenceNumber The notification sequence number within the source object. * @param message The detailed message. * */ public Notification(String type, Object source, long sequenceNumber, String message) { super(source); this.source = source; this.type = type; this.sequenceNumber = sequenceNumber; this.timeStamp = (new java.util.Date()).getTime(); this.message = message; } /** * Creates a Notification object. * * @param type The notification type. * @param source The notification source. * @param sequenceNumber The notification sequence number within the source object. * @param timeStamp The notification emission date. * */ public Notification(String type, Object source, long sequenceNumber, long timeStamp) { super(source); this.source = source; this.type = type; this.sequenceNumber = sequenceNumber; this.timeStamp = timeStamp; } /** * Creates a Notification object. * * @param type The notification type. * @param source The notification source. * @param sequenceNumber The notification sequence number within the source object. * @param timeStamp The notification emission date. * @param message The detailed message. * */ public Notification(String type, Object source, long sequenceNumber, long timeStamp, String message) { super(source); this.source = source; this.type = type; this.sequenceNumber = sequenceNumber; this.timeStamp = timeStamp; this.message = message; } /** * Sets the source. * * @param source the new source for this object. * * @see EventObject#getSource */ public void setSource(Object source) { super.source = source; this.source = source; } /** * Get the notification sequence number. * * @return The notification sequence number within the source object. It's a serial number * identifying a particular instance of notification in the context of the notification source. * The notification model does not assume that notifications will be received in the same order * that they are sent. The sequence number helps listeners to sort received notifications. * * @see #setSequenceNumber */ public long getSequenceNumber() { return sequenceNumber; } /** * Set the notification sequence number. * * @param sequenceNumber The notification sequence number within the source object. It is * a serial number identifying a particular instance of notification in the * context of the notification source. * * @see #getSequenceNumber */ public void setSequenceNumber(long sequenceNumber) { this.sequenceNumber = sequenceNumber; } /** * Get the notification type. * * @return The notification type. It's a string expressed in a dot notation * similar to Java properties. It is recommended that the notification type * should follow the reverse-domain-name convention used by Java package * names. An example of a notification type is com.example.alarm.router. */ public String getType() { return type; } /** * Get the notification timestamp. * * @return The notification timestamp. * * @see #setTimeStamp */ public long getTimeStamp() { return timeStamp; } /** * Set the notification timestamp. * * @param timeStamp The notification timestamp. It indicates when the notification was generated. * * @see #getTimeStamp */ public void setTimeStamp(long timeStamp) { this.timeStamp = timeStamp; } /** * Get the notification message. * * @return The message string of this notification object. * */ public String getMessage() { return message; } /** * Get the user data. * * @return The user data object. It is used for whatever data * the notification source wishes to communicate to its consumers. * * @see #setUserData */ public Object getUserData() { return userData; } /** * Set the user data. * * @param userData The user data object. It is used for whatever data * the notification source wishes to communicate to its consumers. * * @see #getUserData */ public void setUserData(Object userData) { this.userData = userData; } /** * Returns a String representation of this notification. * * @return A String representation of this notification. */ @Override public String toString() { return super.toString() + "[type=" + type + "][message=" + message + "]"; } /** * Deserializes a {@link Notification} from an {@link ObjectInputStream}. */ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { // New serial form ignores extra field "sourceObjectName" in.defaultReadObject(); super.source = source; } /** * Serializes a {@link Notification} to an {@link ObjectOutputStream}. */ private void writeObject(ObjectOutputStream out) throws IOException { if (compat) { // Serializes this instance in the old serial form // ObjectOutputStream.PutField fields = out.putFields(); fields.put("type", type); fields.put("sequenceNumber", sequenceNumber); fields.put("timeStamp", timeStamp); fields.put("userData", userData); fields.put("message", message); fields.put("source", source); out.writeFields(); } else { // Serializes this instance in the new serial form // out.defaultWriteObject(); } } }