Mega Code Archive
Demonstrates that mutable objects are copied, not passed by reference, when you use them to create message objects
<![CDATA[
/*
* @(#)ObjectMessages.java 1.3 02/05/02
*
* Copyright (c) 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
*
* Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
* modify and redistribute this software in source and binary code form,
* provided that i) this copyright notice and license appear on all copies of
* the software; and ii) Licensee does not utilize the software in a manner
* which is disparaging to Sun.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
* IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
* NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
* LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
* CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
* OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* This software is not designed or intended for use in on-line control of
* aircraft, air traffic, aircraft navigation or aircraft communications; or in
* the design, construction, operation or maintenance of any nuclear
* facility. Licensee represents and warrants that it will not use or
* redistribute the Software for such purposes.
*/
import javax.jms.*;
/**
* The ObjectMessages class consists only of a main method, which demonstrates
* that mutable objects are copied, not passed by reference, when you use them
* to create message objects.
* <p>
* The example uses only an ObjectMessage and a BytesMessage, but the same is
* true for all message formats.
*
* @author Kim Haase
* @version 1.4, 08/09/00
*/
public class ObjectMessages {
/**
* Main method. Takes no arguments.
*/
public static void main(String[] args) {
ConnectionFactory connectionFactory = null;
Connection connection = null;
Session session = null;
ObjectMessage objectMessage = null;
String object = "A String is an object.";
BytesMessage bytesMessage = null;
byte[] byteArray = {3, 5, 7, 9, 11};
final int ARRLEN = 5;
int length = 0;
byte[] inByteData = new byte[ARRLEN];
int exitResult = 0;
try {
connectionFactory =
SampleUtilities.getConnectionFactory();
connection =
connectionFactory.createConnection();
session = connection.createSession(false,
Session.AUTO_ACKNOWLEDGE);
} catch (Exception e) {
System.out.println("Connection problem: " + e.toString());
if (connection != null) {
try {
connection.close();
} catch (JMSException ee) {}
}
System.exit(1);
}
try {
/*
* Create an ObjectMessage from a String.
* Modify the original object.
* Read the message, proving that the object in the message
* has not changed.
*/
objectMessage = session.createObjectMessage();
System.out.println("Writing ObjectMessage with string: " + object);
objectMessage.setObject(object);
object = "I'm a different String now.";
System.out.println("Changed string; object is now: " + object);
System.out.println("ObjectMessage contains: " +
(String) objectMessage.getObject());
/*
* Create a BytesMessage from an array.
* Modify an element of the original array.
* Reset and read the message, proving that contents of the message
* have not changed.
*/
bytesMessage = session.createBytesMessage();
System.out.print("Writing BytesMessage with array: ");
for (int i = 0; i < ARRLEN; i++) {
System.out.print(" " + byteArray[i]);
}
System.out.println();
bytesMessage.writeBytes(byteArray);
byteArray[1] = 13;
System.out.print("Changed array element; array is now: ");
for (int i = 0; i < ARRLEN; i++) {
System.out.print(" " + byteArray[i]);
}
System.out.println();
bytesMessage.reset();
length = bytesMessage.readBytes(inByteData);
System.out.print("BytesMessage contains: ");
for (int i = 0; i < length; i++) {
System.out.print(" " + inByteData[i]);
}
System.out.println();
} catch (JMSException e) {
System.out.println("Exception occurred: " + e.toString());
exitResult = 1;
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
exitResult = 1;
}
}
}
SampleUtilities.exit(exitResult);
}
}
jms.zip( 65 k)
]]>