Java tutorial
/* * 2001-2009, Progress Software Corporation and/or its subsidiaries or affiliates. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. Sample Application Writing a Basic JMS Application Using Subscribe When you run this program, it will subscribe to any group of messages specified in a properties file. [See comments in MessageMonitor.properties for information on this file.] Every message topic being monitored will be displayed to a Java window. Usage: java MessageMonitor Suggested demonstration: - Start one instance of this application: java MessageMonitor - Run one or more Chat and/or DurableChat window(s). - Enter messages on the various chat windows. - Watch the MessageMonitor display the messages. */ import org.apache.activemq.*; import javax.swing.JTextArea; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JButton; import javax.swing.text.Highlighter; import javax.swing.text.DefaultHighlighter; import javax.swing.text.BadLocationException; import javax.swing.border.CompoundBorder; import javax.swing.border.EmptyBorder; import javax.swing.border.BevelBorder; import javax.swing.border.SoftBevelBorder; import java.awt.Toolkit; import java.awt.Dimension; import java.awt.BorderLayout; import java.awt.Rectangle; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.awt.event.ActionListener; import java.awt.event.ActionEvent; import javax.jms.Topic; import javax.jms.Session; import javax.jms.Connection; import javax.jms.MessageConsumer; import javax.jms.MessageListener; import java.io.FileInputStream; import java.util.Vector; import java.util.Properties; import java.util.StringTokenizer; public class MessageMonitor extends JFrame { private static final String DEFAULT_PROPERTIES_FILE = "MessageMonitor.properties"; String propertiesFile = DEFAULT_PROPERTIES_FILE; String brokerHostPort = "localhost"; String connectID = "MessageMonitor"; String userID = "Administrator"; String subscriptionTopics = "jms.samples.chat"; String textFontName = "Dialog"; String textFontStyle = "PLAIN"; String textFontSize = "12"; String title = "MessageMonitor"; JTextArea textArea = new JTextArea(); JScrollPane scrollPane = new JScrollPane(textArea); JButton clearButton = new JButton("Clear"); Connection connection = null; Session session = null; private String user = ActiveMQConnection.DEFAULT_USER; private String password = ActiveMQConnection.DEFAULT_PASSWORD; private String url = ActiveMQConnection.DEFAULT_BROKER_URL; /** Constructor for MessageMonitor window. */ public MessageMonitor() { loadProperties(); setTitle(title); // Connect to Message Broker try { javax.jms.ConnectionFactory factory; factory = new ActiveMQConnectionFactory(user, password, url); connection = factory.createConnection(userID, password); session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); } catch (javax.jms.JMSException jmse) { System.err.println("Cannot connect to Broker"); jmse.printStackTrace(); System.exit(1); } // Subscribe to Topics StringTokenizer topics = new StringTokenizer(subscriptionTopics, ","); while (topics.hasMoreTokens()) { try { String topicName = topics.nextToken(); System.out.println("Subscribing to: " + topicName); new Subscription(session.createTopic(topicName)); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } } // Set up the viewing area. textArea.setEditable(false); scrollPane.setBorder( new CompoundBorder(new EmptyBorder(6, 6, 6, 6), new SoftBevelBorder(BevelBorder.LOWERED))); getContentPane().add(scrollPane, BorderLayout.CENTER); getContentPane().add(clearButton, BorderLayout.SOUTH); clearButton.addActionListener(new OnClear()); // Start the connection so that we can now receive messages. try { connection.start(); } catch (javax.jms.JMSException jmse) { System.err.println("Cannot start connection"); jmse.printStackTrace(); System.exit(1); } } /** Class to handle the subsciption to messages. */ public class Subscription implements javax.jms.MessageListener { public Subscription(Topic topic) { try { topicSubscriber = session.createConsumer(topic); topicSubscriber.setMessageListener(this); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } } /** * Handle the text message * (as specified in the javax.jms.MessageListener interface). */ public void onMessage(javax.jms.Message message) { String msgBody = null; String msgClass = null; if (message instanceof javax.jms.TextMessage) { msgClass = "javax.jms.TextMessage"; try { msgBody = ((javax.jms.TextMessage) message).getText(); } catch (javax.jms.JMSException jmse) { msgBody = ""; } } else { return; } try { textArea.append("\n"); textArea.append( "-----------------------------------------------------------------------------------------------------\n"); // textArea.append("Class: " + msgClass + "\n"); textArea.append("The following message, received on topic " + ((Topic) message.getJMSDestination()).getTopicName() + ", was sent by\n"); //textArea.append("\n"); textArea.append(msgBody); // Ensure Appended Text is Visible Rectangle area = textArea.modelToView(textArea.getText().length()); if (area != null) textArea.scrollRectToVisible(area); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } catch (BadLocationException ble) { ble.printStackTrace(); } } MessageConsumer topicSubscriber = null; } // // NOTE: the remainder of this sample deals with reading arguments // and does not utilize any JMS classes or code. // /** Main program entry point. */ public static void main(String[] args) { // There should be no arguments to this program. if (args.length > 0) { printUsage(); System.exit(1); } MessageMonitor messageMonitor = new MessageMonitor(); messageMonitor.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); screenSize.height = screenSize.height / 2; screenSize.width = screenSize.width / 2; messageMonitor.setSize(screenSize); messageMonitor.setVisible(true); } /** Prints the usage. */ private static void printUsage() { StringBuffer use = new StringBuffer(); use.append("\nusage: MessageMonitor\n\n"); use.append("Properties for this sample can be set in a properties file.\n"); String dfltFile = System.getProperty("propertiesFile", DEFAULT_PROPERTIES_FILE); use.append("[Default file: " + dfltFile + "]\n\n"); System.out.print(use); } /** Load the window and JMS properties from a file. */ private void loadProperties() { try { Properties properties = new Properties(); propertiesFile = System.getProperty("propertiesFile", propertiesFile); properties.load(new FileInputStream(propertiesFile)); // Connection Properties brokerHostPort = properties.getProperty("brokerHostPort", brokerHostPort).trim(); connectID = properties.getProperty("connectID", connectID).trim(); userID = properties.getProperty("userID", userID).trim(); password = properties.getProperty("password", password).trim(); // Subscription Properties subscriptionTopics = properties.getProperty("subscriptionTopics", subscriptionTopics).trim(); // Text Properties textFontName = properties.getProperty("textFontName", textFontName).trim(); textFontStyle = properties.getProperty("textFontSize", textFontStyle).trim(); textFontSize = properties.getProperty("textFontSize", textFontSize).trim(); // Window Properties title = properties.getProperty("title", title).trim(); } catch (java.io.FileNotFoundException fnfe) { System.out.println(propertiesFile + " not found: using defaults"); // Use Defaults } catch (java.io.IOException ioe) { ioe.printStackTrace(); } } /** Class to handle the "Clear" button action. */ public class OnClear implements ActionListener { public void actionPerformed(ActionEvent evt) { textArea.setText(""); } } }