實戰Comet 應用程式開發

                
public class BrownianMotionServlet extends BayeuxServlet {

    @Override
    public void registerURL() {
        getServletUtil().addClientManager("/brownianMotionServlet", clientManager);
    }

    @Override
    public void setProperties() {
        setCometTimeout(30000);
        setClientPollInterval(2);
        setRouterType(JMS);
        setClientsCanPublish(false);
    }
}

                
dojo.addOnLoad(function(){


    dojox.cometd.subscribe("/motion", window, "display");
    initControls();
    getTemperature();
});

                
public class AppInit extends javax.servlet.http.HttpServlet {
    
    private static final int SNAPSHOT_INTERVAL = 5000;

    private static final int PARTICLE_NUMBER = 100;

    public static final String TIMER_KEY = "PublishTimer";
    
    public static final String UPDATER_KEY = "MotionUpdater";
    
    public static final String MOTION_TOPIC = "/motion";
    
    private static final Logger logger = Logger.getLogger(AppInit.class.getName());

    @Override
    public void init() throws ServletException {
        super.init();
        MotionSnapshot snapshot = new MotionSnapshot();
        snapshot.setParticles(ParticleGenerator.generate(PARTICLE_NUMBER));
        MotionUpdater updater = new MotionUpdater();
        getServletContext().setAttribute(UPDATER_KEY, updater);
        try {
            DataPublisher publisher = new DataPublisher();
            Timer timer = new Timer();
            //建立定時器
            MotionTimer mt = new MotionTimer(snapshot, updater, publisher);
            timer.scheduleAtFixedRate(mt, 1000, SNAPSHOT_INTERVAL);
            getServletContext().setAttribute(TIMER_KEY, timer);
            
            logger.info("Brownian motion simulation started successfully.");
            
        } catch (Exception e) {
            logger.log(Level.WARNING, e.getMessage(), e);
        }
    }

    private class MotionTimer extends TimerTask {
        
        private MotionSnapshot snapshot;

        private MotionUpdater updater;

        private DataPublisher publisher;

        public MotionTimer(MotionSnapshot snapshot, MotionUpdater updater,
                DataPublisher publisher) {
            this.snapshot = snapshot;
            this.updater = updater;
            this.publisher = publisher;
        }

        @Override
        public void run() {
            updater.update(snapshot);
            List pairs = snapshot.getSnapshot();
            StringBuilder builder = new StringBuilder();
            builder.append("[");
            for (PositionPair pair : pairs) {
                builder.append("{\"x\":");
                builder.append(pair.getPosX());
                builder.append(",\"y\":");
                builder.append(pair.getPosY());
                builder.append("},");
            }
            builder.deleteCharAt(builder.length() - 1);
            builder.append("]");
            try {
                //傳送資料
                publisher.publish(MOTION_TOPIC, builder.toString());
            } catch (JMSException e) {
                logger.log(Level.WARNING, e.getMessage(), e);
            }
        }

    }

}

                
dojo.require("dojox.cometd");
dojo.addOnLoad(function(){
    dojox.cometd.init("brownianMotionServlet")
    dojox.cometd.subscribe("/motion", window, "display");
    initControls();
    getTemperature();
});
            
function display(msg){
    dojo.byId("motionArea").innerHTML = "";
    dojo.forEach(msg.data || [], function(particle) {
        var div = dojo.doc.createElement("div");
        dojo.addClass(div, "particle");
        dojo._setBox(div, particle.x, particle.y);
        dojo.byId("motionArea").appendChild(div);
    });
}

                
public class MotionControlServlet extends HttpServlet implements Servlet {

    private static final int MAX_TEMPERATURE = 200;

    private static final Logger logger = Logger
            .getLogger(MotionControlServlet.class.getName());

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        resp.setContentType("text/plain");
        String peration = req.getParameter("operation");
        if (operation == null) {
            logger.warning("Client has sent empty operation!");
            resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            resp.getOutputStream().print("Please specify the operation!");
            return;
        }

        if (operation.equalsIgnoreCase("getTemperature")) {
            MotionUpdater updater = (MotionUpdater) getServletConfig()
                    .getServletContext().getAttribute(AppInit.UPDATER_KEY);
            if (updater != null) {
                int temperature = updater.getTemperature();
                resp.setStatus(HttpServletResponse.SC_OK);
                resp.getOutputStream().print(temperature);
            }
            else {
                resp.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
                resp.getOutputStream()
                    .print("Can not get the temperature, please try again later!");
            }
        } else {
            resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            resp.getOutputStream().print("Unknown operation type!");
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        resp.setContentType("text/plain");
        String peration = req.getParameter("operation");

        if (operation == null) {
            logger.warning("Client has sent empty operation!");
            resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            resp.getOutputStream().print("Please specify the operation!");
            return;
        }
        if (operation.equalsIgnoreCase("changeTemperature")) {
            String tempStr = req.getParameter("temperature");
            if (tempStr == null || tempStr.trim().equals("")) {
                logger.warning("Client has sent empty value of temperature!");
                resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
                resp.getOutputStream().print("Please specify the temperature!");
                return;
            }

            int temperature = 0;
            try {
                temperature = Math.min(Integer.parseInt(tempStr),
                        MAX_TEMPERATURE);
            } catch (NumberFormatException nfe) {
                logger.log(Level.WARNING,
                        "Client has sent invalid value of temperature!", nfe);
                resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
                resp.getOutputStream()
                    .print("The value of temperature must be a number!");
                return;
            }

            resp.setStatus(HttpServletResponse.SC_OK);

            MotionUpdater updater = (MotionUpdater) getServletConfig()
                    .getServletContext().getAttribute(AppInit.UPDATER_KEY);
            if (updater != null) {
                updater.setTemperature(temperature);
                resp.getOutputStream().print(temperature);
                logger.info("Temperature has been changed to " + temperature);
            }
        } else {
            resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            resp.getOutputStream().print("Unknown operation type!");
        }
    }

}

                
//獲取模擬時的溫度
function getTemperature() {
    var messageBox = dojo.byId("messageBox");
    messageBox.innerHTML = "";
    dojo.xhrGet({
        url : "/BrownianMotion/control?operation=getTemperature",
        handleAs : "text",
        load : function(response) {
            var temperature = dojo.byId("temperature");
            temperature.innerHTML = response;
        },
        error : function(response, ioArgs) {
            messageBox.innerHTML = ioArgs.xhr.responseText;
        }
    });
}

//更新模擬時的溫度            
function updateTemperature() {
    var messageBox = dojo.byId("messageBox");
    messageBox.innerHTML = "";
    var tempInput = dojo.byId("temperatureInput");
    var value = dojo.trim(tempInput.value);
    if (value.length > 0) {
        dojo.xhrPost({
            url : "/BrownianMotion/control",
            handleAs : "text",
            content : {
                "operation" : "changeTemperature",
                "temperature" : value
            },
            load : function(response) {
                var temperature = dojo.byId("temperature");
                temperature.innerHTML = response;
            },
            error : function(response) {
                messageBox.innerHTML = ioArgs.xhr.responseText;
            }
        });
    }
}

                
public class MeetingRoomServlet extends BayeuxServlet {

    @Override
    public void registerURL() {
        getServletUtil().addClientManager("/meetingRoomServlet", clientManager);
    }

    @Override
    public void setProperties() {
        setCometTimeout(30000);
        setClientPollInterval(5);
        setRouterType(SIMPLE);
        setClientsCanPublish(true);
    }
}

                
var MeetingRoom = (function() {
    var nickName = "匿名使用者";
    
    var chatArea;
    
    var topic = "/chat";
    
    return {
        //顯示訊息
        displayMessage : function(msgObject) {
            var date = new Date();
            try {
                date.setTime(msgObject["dateTime"]);
            }
            catch (error) {
                
            }
             var msg = ["", 
                decodeURIComponent(msgObject["sender"]) || "匿名使用者", 
                " 說：",     
                decodeURIComponent(msgObject["message"]), 
                "  (", date.toLocaleString(), ")"].join("");
            var div = dojo.doc.createElement("div");
            div.innerHTML = msg;
            chatArea.appendChild(div);
        },
        
        //傳送訊息
        sendMessage : function(message) {
            message = dojo.trim(message);
            if (message.length > 0) {
                dojox.cometd.publish(topic, 
                {"sender" : encodeURIComponent(nickName), 
                "message": encodeURIComponent(message), 
                "dateTime" : new Date().getTime()});
            }
        },
        
        //修改暱稱
        changeNickName : function(newNickName) {
            nickName = newNickName;
        },
        
        init : function() {
            chatArea = dojo.byId("chatArea");
        }
    }
})();