transactedexample.java

《j2ee经典实例详解》的源代码。原书无附带光盘。介绍的是一个在线银行系统的例子。绝对难得

/*
 * Copyright (c) 2005 Sun Microsystems, Inc.  All rights reserved.  U.S.
 * Government Rights - Commercial software.  Government users are subject
 * to the Sun Microsystems, Inc. standard license agreement and
 * applicable provisions of the FAR and its supplements.  Use is subject
 * to license terms.
 *
 * This distribution may include materials developed by third parties.
 * Sun, Sun Microsystems, the Sun logo, Java and J2EE are trademarks
 * or registered trademarks of Sun Microsystems, Inc. in the U.S. and
 * other countries.
 *
 * Copyright (c) 2005 Sun Microsystems, Inc. Tous droits reserves.
 *
 * Droits du gouvernement americain, utilisateurs gouvernementaux - logiciel
 * commercial. Les utilisateurs gouvernementaux sont soumis au contrat de
 * licence standard de Sun Microsystems, Inc., ainsi qu'aux dispositions
 * en vigueur de la FAR (Federal Acquisition Regulations) et des
 * supplements a celles-ci.  Distribue par des licences qui en
 * restreignent l'utilisation.
 *
 * Cette distribution peut comprendre des composants developpes par des
 * tierces parties. Sun, Sun Microsystems, le logo Sun, Java et J2EE
 * sont des marques de fabrique ou des marques deposees de Sun
 * Microsystems, Inc. aux Etats-Unis et dans d'autres pays.
 */


import java.util.*;
import javax.jms.*;


public class TransactedExample {
    public static String vendorOrderQueueName = null;
    public static String retailerConfirmQueueName = null;
    public static String supplierOrderTopicName = null;
    public static String vendorConfirmQueueName = null;

    /**
     * Creates the Retailer and Vendor classes and the two
     * supplier classes, then starts the threads.
     *
     * @param quantity    the quantity specified on the command
     *                    line
     */
    public static void run_threads(int quantity) {
        Retailer r = new Retailer(quantity);
        Vendor v = new Vendor();
        GenericSupplier ms =
            new GenericSupplier("Monitor", supplierOrderTopicName);
        GenericSupplier ss =
            new GenericSupplier("Hard Drive", supplierOrderTopicName);

        ms.start();
        ss.start();
        r.start();
        v.start();

        try {
            ms.join();
            ss.join();
            r.join();
            v.join();
        } catch (InterruptedException e) {
        }
    }

    /**
     * Reads the order quantity from the command line, then
     * calls the run_threads method to execute the program
     * threads.
     *
     * @param args    the quantity of computers being ordered
     */
    public static void main(String[] args) {
        TransactedExample te = new TransactedExample();
        int quantity = 0;

        if (args.length != 1) {
            System.out.println("Program takes numerical argument.");
            System.err.println("Program assumes three " +
                "queues named jms/AQueue, jms/BQueue, and jms/CQueue " +
                "and one topic named jms/OTopic");
            System.exit(1);
        }

        te.vendorOrderQueueName = new String("jms/AQueue");
        te.retailerConfirmQueueName = new String("jms/BQueue");
        te.supplierOrderTopicName = new String("jms/OTopic");
        te.vendorConfirmQueueName = new String("jms/CQueue");
        quantity = (new Integer(args[0])).intValue();
        System.out.println("Quantity to be ordered is " + quantity);

        if (quantity > 0) {
            te.run_threads(quantity);
            System.exit(0);
        } else {
            System.out.println("Quantity must be positive and " + "nonzero");
            System.exit(1);
        }
    }

    /**
     * The Retailer class orders a number of computers by sending
     * a message to a vendor.  It then waits for the order to be
     * confirmed.
     *
     * In this example, the Retailer places two orders, one for
     * the quantity specified on the command line and one for
     * twice that number.
     *
     * This class does not use transactions.
     */
    public static class Retailer extends Thread {
        int quantity = 0;

        /**
         * Constructor.  Instantiates the retailer with the
         * quantity of computers being ordered.
         *
         * @param q    the quantity specified in the program
         *             arguments
         */
        public Retailer(int q) {
            quantity = q;
        }

        /**
         * Runs the thread.
         */
        public void run() {
            ConnectionFactory connectionFactory = null;
            Connection connection = null;
            Session session = null;
            javax.jms.Queue vendorOrderQueue = null;
            javax.jms.Queue retailerConfirmQueue = null;
            MessageProducer producer = null;
            MapMessage outMessage = null;
            MessageConsumer orderConfirmReceiver = null;
            MapMessage inMessage = null;

            try {
                connectionFactory = SampleUtilities.getConnectionFactory();
                connection = connectionFactory.createConnection();
                session =
                    connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
                vendorOrderQueue =
                    SampleUtilities.getQueue(vendorOrderQueueName, session);
                retailerConfirmQueue =
                    SampleUtilities.getQueue(retailerConfirmQueueName, session);
            } catch (Exception e) {
                System.err.println("Connection problem: " + e.toString());
                System.err.println("Program assumes three " +
                    "queues named jms/AQueue, jms/BQueue, and jms/CQueue " +
                    "and one topic named jms/OTopic");

                if (connection != null) {
                    try {
                        connection.close();
                    } catch (JMSException ee) {
                    }
                }

                System.exit(1);
            }

            /*
             * Create non-transacted session and sender for
             * vendor order queue.
             * Create message to vendor, setting item and
             * quantity values.
             * Send message.
             * Create receiver for retailer confirmation queue.
             * Get message and report result.
             * Send an end-of-message-stream message so vendor
             * will stop processing orders.
             */
            try {
                producer = session.createProducer(vendorOrderQueue);
                outMessage = session.createMapMessage();
                outMessage.setString("Item", "Computer(s)");
                outMessage.setInt("Quantity", quantity);
                outMessage.setJMSReplyTo(retailerConfirmQueue);
                producer.send(outMessage);
                System.out.println("Retailer: ordered " + quantity +
                    " computer(s)");

                orderConfirmReceiver =
                    session.createConsumer(retailerConfirmQueue);
                connection.start();
                inMessage = (MapMessage) orderConfirmReceiver.receive();

                if (inMessage.getBoolean("OrderAccepted") == true) {
                    System.out.println("Retailer: Order filled");
                } else {
                    System.out.println("Retailer: Order not " + "filled");
                }

                System.out.println("Retailer: placing another " + "order");
                outMessage.setInt("Quantity", quantity * 2);
                producer.send(outMessage);
                System.out.println("Retailer: ordered " +
                    outMessage.getInt("Quantity") + " computer(s)");
                inMessage = (MapMessage) orderConfirmReceiver.receive();

                if (inMessage.getBoolean("OrderAccepted") == true) {
                    System.out.println("Retailer: Order filled");
                } else {
                    System.out.println("Retailer: Order not " + "filled");
                }

                /*
                 * Send a non-text control message indicating end
                 * of messages.
                 */
                producer.send(session.createMessage());
            } catch (Exception e) {
                System.err.println("Retailer: Exception " + "occurred: " +
                    e.toString());
                e.printStackTrace();
            } finally {
                if (connection != null) {
                    try {
                        connection.close();
                    } catch (JMSException e) {
                    }
                }
            }
        }
    }

    /**
     * The Vendor class uses one transaction to receive the
     * computer order from the retailer and order the needed
     * number of monitors and disk drives from its suppliers.
     * At random intervals, it throws an exception to simulate a
     * database problem and cause a rollback.
     *
     * The class uses an asynchronous message listener to process
     * replies from suppliers. When all outstanding supplier
     * inquiries complete, it sends a message to the Retailer
     * accepting or refusing the order.
     */
    public static class Vendor extends Thread {
        Random rgen = new Random();
        int throwException = 1;

        /**
         * Runs the thread.
         */
        public void run() {
            ConnectionFactory connectionFactory = null;
            Connection connection = null;
            Session session = null;
            Session asyncSession = null;
            javax.jms.Queue vendorOrderQueue = null;
            Topic supplierOrderTopic = null;
            javax.jms.Queue vendorConfirmQueue = null;
            MessageConsumer vendorOrderReceiver = null;
            MessageProducer supplierOrderProducer = null;
            MapMessage orderMessage = null;
            MessageConsumer vendorConfirmReceiver = null;
            VendorMessageListener listener = null;
            Message inMessage = null;
            MapMessage vendorOrderMessage = null;
            Message endOfMessageStream = null;
            Order order = null;
            int quantity = 0;

            try {
                connectionFactory = SampleUtilities.getConnectionFactory();
                connection = connectionFactory.createConnection();
                session = connection.createSession(true, 0);
                asyncSession = connection.createSession(true, 0);
                vendorOrderQueue =
                    SampleUtilities.getQueue(vendorOrderQueueName, session);
                supplierOrderTopic =
                    SampleUtilities.getTopic(supplierOrderTopicName, session);
                vendorConfirmQueue =
                    SampleUtilities.getQueue(vendorConfirmQueueName, session);
            } catch (Exception e) {
                System.err.println("Connection problem: " + e.toString());
                System.err.println("Program assumes three " +
                    "queues named jms/AQueue, jms/BQueue, and jms/CQueue " +
                    "and one topic named jms/OTopic");

                if (connection != null) {
                    try {
                        connection.close();
                    } catch (JMSException ee) {
                    }
                }