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 Point-to-Point (Queues) with a Message Selector This sample starts up with a username, and the queues you are sending on, and receiving on. When messages are sent to a queue a property is set in the message header to a property value supplied on the command line. A separate command line value is used as a message selector for messages in the receive queue. In this sample we choose to create a property named "Department" Writing a line and pressing enter will send the message only to the indicated 'Talk' partner (or QueueReceiver). Usage: java SelectorTalk -b <broker:port> -u <username> -p <password> -qs <queue> -qr <queue> -s <selection> -b broker:port points to your message broker Default: tcp://localhost:61616 -u username must be unique (but is not checked) -p password password for user (not checked) -qr queue name of queue to receive -qs queue name of queue to send -s selector the message selection value You must specify either a queue for sending or receiving (or both) as well as a value with which to select received messages. Suggested demonstration: - In separate console windows with the environment set, start instances of the application under unique user names. For example: java SelectorTalk -u BOB -s SALES -qr Q1 -qs Q2 java SelectorTalk -u SALLY -s SALES -qr Q2 -qs Q1 - Enter text and then press Enter to send the message. - See messages appear under the user's indicated name. - Try changing the message selector on one console and note that it will no longer receive messages. - Stop a session by pressing CTRL+C in its console window. */ import org.apache.activemq.*; public class SelectorTalk implements javax.jms.MessageListener { private static final String DEFAULT_BROKER_NAME = "tcp://localhost:61616"; private static final String PROPERTY_NAME = "Department"; private static final String DEFAULT_PASSWORD = "password"; private static final int MESSAGE_LIFESPAN = 1800000; // milliseconds (30 minutes) private javax.jms.Connection connect = null; private javax.jms.Session sendSession = null; private javax.jms.Session receiveSession = null; private javax.jms.MessageProducer sender = null; /** Create JMS client for sending and receiving messages. */ private void talker(String broker, String username, String password, String rQueue, String sQueue, String selection) { // Create a connection. try { javax.jms.ConnectionFactory factory; factory = new ActiveMQConnectionFactory(username, password, broker); connect = factory.createConnection(username, password); sendSession = connect.createSession(false, javax.jms.Session.AUTO_ACKNOWLEDGE); receiveSession = connect.createSession(false, javax.jms.Session.AUTO_ACKNOWLEDGE); } catch (javax.jms.JMSException jmse) { System.err.println("error: Cannot connect to Broker - " + broker); jmse.printStackTrace(); System.exit(1); } // Create Sender and Receiver 'Talk' queues try { if (sQueue != null) { javax.jms.Queue sendQueue = sendSession.createQueue(sQueue); sender = sendSession.createProducer(sendQueue); } if (rQueue != null) { //NOTE: the Queue Receiver is set up with the Message Selector: javax.jms.Queue receiveQueue = receiveSession.createQueue(rQueue); javax.jms.MessageConsumer qReceiver = receiveSession.createConsumer(receiveQueue, PROPERTY_NAME + " = \'" + selection + "\'"); qReceiver.setMessageListener(this); connect.start(); } } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); exit(); } try { if (rQueue != null) System.out.println(""); else System.out.println("\nNo receiving queue specified.\n"); // Read all standard input and send it as a message. java.io.BufferedReader stdin = new java.io.BufferedReader(new java.io.InputStreamReader(System.in)); if (sQueue != null) System.out.println("SelectorTalk application:\n" + "=========================\n" + "The application user " + username + " connects to the broker at " + DEFAULT_BROKER_NAME + ".\n" + "The application will send messages with " + PROPERTY_NAME + " set to " + selection + " to the " + sQueue + " queue.\n" + "The application creates a receiver on the " + rQueue + " queue selecting only messages where " + PROPERTY_NAME + " is " + selection + ".\n\n" + "Type some text, and then press Enter to publish it as a TextMesssage from " + username + ".\n"); else System.out.println("\nPress CTRL-C to exit.\n"); while (true) { String s = stdin.readLine(); if (s == null) exit(); else if (s.length() > 0 && sQueue != null) { javax.jms.TextMessage msg = sendSession.createTextMessage(); msg.setText(username + ": " + s); // NOTE: here we set the property for each sent message. msg.setStringProperty(PROPERTY_NAME, selection); sender.send(msg, javax.jms.DeliveryMode.PERSISTENT, javax.jms.Message.DEFAULT_PRIORITY, MESSAGE_LIFESPAN); } } } catch (java.io.IOException ioe) { ioe.printStackTrace(); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } // Close the connection. exit(); } /** * Handle the message * (as specified in the javax.jms.MessageListener interface). */ public void onMessage(javax.jms.Message aMessage) { try { // Cast the message as a text message. javax.jms.TextMessage textMessage = (javax.jms.TextMessage) aMessage; // This handler reads a single String from the // message and prints it to the standard output. try { String string = textMessage.getText(); System.out.println(string); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } } catch (java.lang.RuntimeException rte) { rte.printStackTrace(); } } /** Cleanup resources and then exit. */ private void exit() { try { connect.close(); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } System.exit(0); } // // 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 argv[]) { // Is there anything to do? if (argv.length == 0) { printUsage(); System.exit(1); } // Values to be read from parameters String broker = DEFAULT_BROKER_NAME; String username = null; String password = DEFAULT_PASSWORD; String qSender = null; String qReceiver = null; String selection = null; // Check parameters for (int i = 0; i < argv.length; i++) { String arg = argv[i]; // Options if (!arg.startsWith("-")) { System.err.println("error: unexpected argument - " + arg); printUsage(); System.exit(1); } else { if (arg.equals("-b")) { if (i == argv.length - 1 || argv[i + 1].startsWith("-")) { System.err.println("error: missing broker name:port"); System.exit(1); } broker = argv[++i]; continue; } if (arg.equals("-u")) { if (i == argv.length - 1 || argv[i + 1].startsWith("-")) { System.err.println("error: missing user name"); System.exit(1); } username = argv[++i]; continue; } if (arg.equals("-p")) { if (i == argv.length - 1 || argv[i + 1].startsWith("-")) { System.err.println("error: missing password"); System.exit(1); } password = argv[++i]; continue; } if (arg.equals("-qr")) { if (i == argv.length - 1 || argv[i + 1].startsWith("-")) { System.err.println("error: missing receive queue parameter"); System.exit(1); } qReceiver = argv[++i]; continue; } if (arg.equals("-qs")) { if (i == argv.length - 1 || argv[i + 1].startsWith("-")) { System.err.println("error: missing send queue parameter"); System.exit(1); } qSender = argv[++i]; continue; } if (arg.equals("-s")) { if (i == argv.length - 1 || argv[i + 1].startsWith("-")) { System.err.println("error: missing selectiion"); System.exit(1); } selection = argv[++i]; continue; } if (arg.equals("-h")) { printUsage(); System.exit(1); } } } // Check values read in. if (username == null) { System.err.println("error: user name must be supplied"); printUsage(); System.exit(1); } if (qReceiver == null && qSender == null) { System.err.println("error: receive queue, or send queue, must be supplied"); printUsage(); System.exit(1); } if (selection == null) { System.err.println("error: selection must be supplied (e.g. -s SALES)\n"); printUsage(); System.exit(1); } // Start the JMS client for the "Talk". SelectorTalk talk = new SelectorTalk(); talk.talker(broker, username, password, qReceiver, qSender, selection); } /** Prints the usage. */ private static void printUsage() { StringBuffer use = new StringBuffer(); use.append("usage: java SelectorTalk (options) ...\n\n"); use.append("options:\n"); use.append(" -b name:port Specify name:port of broker.\n"); use.append(" Default broker: " + DEFAULT_BROKER_NAME + "\n"); use.append(" -u name Specify unique user name. (Required)\n"); use.append(" -p password Specify password for user.\n"); use.append(" Default password: " + DEFAULT_PASSWORD + "\n"); use.append(" -qr queue Specify queue for receiving messages.\n"); use.append(" -qs queue Specify queue for sending messages.\n"); use.append(" -s selection required, selection used to receive messages.\n"); use.append(" -h This help screen.\n"); System.err.println(use); } }