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: - Synchronous Request/Reply - Publish/Subscribe - javax.jms.TopicRequestor class - JMSReplyTo Header When this program runs, it reads input from System.in and then sends the text as a message to the topic "progress.samples.request". A "Replier" class should be waiting for the request. It will reply with a message. NOTE: You must run the TopicReplier first. (Otherwise the syncronous request will block forever.) Usage: java TopicRequestor -b <broker:port> -u <username> -p <password> -b broker:port points to your message broker Default: tcp://localhost:61616 -u username must be unique (but is not checked) Default: SampleRequestor -p password password for user (not checked) Default: password Suggested demonstration: - In a console window with the environment set, start a copy of the Replier. For example: java TopicReplier -u SampleReplier - In another console window, start a Requestor. For example: java TopicRequestor -u SampleRequestor - Enter text in the Requestor window then press Enter. The Replier responds with the message in all uppercase characters. - Start other Requestors with different user names to see that replies are not broadcast to all users. For example: java TopicRequestor -u SampleRequestorToo - Start other Repliers. - See that all repliers are receiving all the messages,(as they should). - See the Requestor only receives one response. java TopicReplier -u toLower -m lowercase */ import org.apache.activemq.*; public class TopicRequestor { private static final String APP_TOPIC = "jms.samples.request"; private static final String DEFAULT_BROKER_NAME = "tcp://localhost:61616"; private static final String DEFAULT_USER_NAME = "SampleRequestor"; private static final String DEFAULT_PASSWORD = "password"; private javax.jms.TopicConnection connect = null; private javax.jms.TopicSession session = null; /** Create JMS client for publishing and subscribing to messages. */ private void start(String broker, String username, String password) { // Create a connection. try { javax.jms.TopicConnectionFactory factory; factory = new ActiveMQConnectionFactory(username, password, broker); connect = factory.createTopicConnection(username, password); session = connect.createTopicSession(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 Topic for all requests. TopicRequestor will be created // as needed. javax.jms.Topic topic = null; try { topic = session.createTopic(APP_TOPIC); // Now that all setup is complete, start the Connection connect.start(); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } try { // Read all standard input and send it as a message. java.io.BufferedReader stdin = new java.io.BufferedReader(new java.io.InputStreamReader(System.in)); System.out.println("\nRequestor application:\n" + "============================\n" + "The application user " + username + " connects to the broker at " + DEFAULT_BROKER_NAME + ".\n" + "The application uses a TopicRequestor to on the " + APP_TOPIC + " topic." + "The Replier application gets the message, and transforms it." + "The Requestor application displays the result.\n\n" + "Type some mixed case text, and then press Enter to make a request.\n"); while (true) { String s = stdin.readLine(); if (s == null) exit(); else if (s.length() > 0) { javax.jms.TextMessage msg = session.createTextMessage(); msg.setText(username + ": " + s); // Instead of publishing, we will use a TopicRequestor. javax.jms.TopicRequestor requestor = new javax.jms.TopicRequestor(session, topic); javax.jms.Message response = requestor.request(msg); // The message should be a TextMessage. Just report it. javax.jms.TextMessage textMessage = (javax.jms.TextMessage) response; System.out.println("[Reply] " + textMessage.getText()); } } } catch (java.io.IOException ioe) { ioe.printStackTrace(); } catch (javax.jms.JMSException jmse) { jmse.printStackTrace(); } } /** Cleanup resources cleanly and 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[]) { // Values to be read from parameters String broker = DEFAULT_BROKER_NAME; String username = DEFAULT_USER_NAME; String password = DEFAULT_PASSWORD; // Check parameters for (int i = 0; i < argv.length; i++) { String arg = argv[i]; 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("-h")) { printUsage(); System.exit(1); } // Invalid argument System.err.println("error: unexpected argument: " + arg); printUsage(); System.exit(1); } // Start the JMS client for the "chat". TopicRequestor requestor = new TopicRequestor(); requestor.start(broker, username, password); } /** Prints the usage. */ private static void printUsage() { StringBuffer use = new StringBuffer(); use.append("usage: java Requestor (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.\n"); use.append(" Default broker: " + DEFAULT_USER_NAME + "\n"); use.append(" -p password Specify password for user.\n"); use.append(" Default password: " + DEFAULT_PASSWORD + "\n"); use.append(" -h This help screen.\n"); System.err.println(use); } }