mediator.java

Java Pattern Oriented Framework (Jt) 是为了实现Java快速开发的面向模式的框架。

package Jt.examples.patterns;
import Jt.*;

/**
 * Chat room implementation based on the Mediator pattern. Colleagues run in separate
 * threads. 
 */

public class Mediator extends JtMediator {

    public static final String JtCLASS_NAME = Mediator.class.getName(); 
    private static final long serialVersionUID = 1L;
    public static final String JOIN = "JOIN";
    public static final String MESSAGE = "MESSAGE";
    public static final String EXIT = "EXIT";

    public Mediator () {
    }


    // Broadcast a message to all the members

    private void broadcastMessage (JtMessage msg) {
        JtMessage tmp;

        if (msg == null)
            return;

        tmp = new JtMessage (JtObject.JtBROADCAST);
        tmp.setMsgContent (msg);

        processMessage (tmp);
    }




    /**
     * Process object messages.
     * <ul>
     * </ul>
     * @param message Jt Message
     */


    public Object processMessage (Object message) {

        String msgid = null;
        JtMessage e = (JtMessage) message;
        Object content;
        JtMessage tmp;
        JtObject colleague;

        if (e == null)
            return null;

        msgid = (String) e.getMsgId ();

        if (msgid == null)
            return null;

        content = e.getMsgContent();
        //data = e.getMsgData ();

        // Remove this object

        if (msgid.equals (JtObject.JtREMOVE)) {
            return (null);     
        }


        // Join the chat room

        if (msgid.equals (Mediator.JOIN)) {



            colleague = (JtObject) e.getMsgContent ();       

            System.out.println (colleague.getObjName() + " has joined");
            tmp = new JtMessage (Mediator.MESSAGE);
            tmp.setMsgContent (colleague.getObjName() + " has joined");

            // Alert everyone about the new member

            broadcastMessage (tmp);

            // Add the new member to the chat room

            tmp = new JtMessage (JtComposite.JtADD_CHILD);
            tmp.setMsgContent (e.getMsgContent ());
            //tmp.setMsgData (colleague.getObjName());
            processMessage (tmp);

            return (this);

        }    

        // Send a message to the chat room (everyone)

        if (msgid.equals (Mediator.MESSAGE)) {

            colleague = (JtObject) e.getMsgData ();  

            broadcastMessage (e);     

            System.out.println (colleague.getObjName() + ":" + content);
            return (this);

        }       

        // Exit the chat room

        if (msgid.equals (Mediator.EXIT)) {

            colleague = (JtObject) e.getMsgContent ();  

            tmp = new JtMessage (Mediator.MESSAGE);
            tmp.setMsgContent (colleague.getObjName() + " is exiting ...");

            broadcastMessage (tmp);     

            System.out.println (colleague.getObjName() + " is exiting ...");

            tmp = new JtMessage (JtComposite.JtREMOVE_CHILD);
            tmp.setMsgData (e.getMsgFrom ());

            return (this);

        } 

        // Let the superclass handle all the other messages

        return (super.processMessage (message));


    }


    static private char waitForInputKey () {
        char c = ' ';

        try {

            c = (char) System.in.read ();
            while (System.in.available () > 0)
                System.in.read ();

        } catch (Exception e) {
            e.printStackTrace ();
        }

        return (c);
    } 

    // Test program

    public static void main(String[] args) {

        JtObject factory = new JtFactory ();

        JtMediator mediator;
        Colleague colleague1, colleague2, colleague3;

        System.out.println ("Press any key to start/stop the chat room demo ...");
        waitForInputKey (); 


        // Create an instance of the chat room

        mediator = (JtMediator) factory.createObject (Mediator.JtCLASS_NAME, "mediator");

        colleague1 = (Colleague) factory.createObject (Colleague.JtCLASS_NAME, "Jenny");
        factory.setValue (colleague1, "greetingMessage", "Hi folks! How are you all doing ?");


        // Activate the first member

        factory.setValue (colleague1, "mediator", mediator);   
        factory.sendMessage (colleague1, new JtMessage (JtObject.JtACTIVATE));


        // Activate the second member

        colleague2 = (Colleague) factory.createObject (Colleague.JtCLASS_NAME, "Daniel");

        factory.setValue (colleague2, "mediator", mediator);   
        factory.sendMessage (colleague2, new JtMessage (JtObject.JtACTIVATE));


        // Activate the third member

        colleague3 = (Colleague) factory.createObject (Colleague.JtCLASS_NAME, "Mary");

        factory.setValue (colleague3, "mediator", mediator);   
        factory.sendMessage (colleague3, new JtMessage (JtObject.JtACTIVATE));



        waitForInputKey (); 

        // Remove the objects

        factory.removeObject ("mediator");
        factory.removeObject ("Jenny");
        factory.removeObject ("Daniel");
        factory.removeObject ("Mary");
    }

}