Jetty example source code file (ChatFilter.java)

This example Jetty source code file (ChatFilter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Jetty tags/keywords

ajaxresponse, arraylist, continuation, http, httpservletrequest, httpsession, httpsession, io, member, member, message, message, request, response, servlet, servletexception, string, string, system, util

The Jetty ChatFilter.java source code

//========================================================================
//$Id: ChatFilter.java,v 1.4 2005/11/14 11:00:33 gregwilkins Exp $
//Copyright 2004-2005 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//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.
//========================================================================

package com.acme;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.mortbay.util.ajax.AjaxFilter;
import org.mortbay.util.ajax.Continuation;
import org.mortbay.util.ajax.ContinuationSupport;

public class ChatFilter extends AjaxFilter
{       
    private Map chatrooms;
    

    /* ------------------------------------------------------------ */
    /* 
     * @see org.mortbay.ajax.AjaxFilter#init(javax.servlet.FilterConfig)
     */
    public void init(FilterConfig filterConfig) throws ServletException
    {
        super.init(filterConfig);
        chatrooms=new HashMap();
    }
    
    /* ------------------------------------------------------------ */
    /* 
     * @see org.mortbay.ajax.AjaxFilter#destroy()
     */
    public void destroy()
    {
        super.destroy();
        chatrooms.clear();
        chatrooms=null;
    }


    /* ------------------------------------------------------------ */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
    {
        HttpSession session = ((HttpServletRequest)request).getSession(true);
        super.doFilter(request,response,chain);
    }
    
    /* ------------------------------------------------------------ */
    /* 
     * @see org.mortbay.ajax.AjaxFilter#handle(java.lang.String, javax.servlet.http.HttpServletRequest, org.mortbay.ajax.AjaxFilter.AjaxResponse)
     */
    public void handle(String method, String message, HttpServletRequest request, AjaxResponse response)
    {
        request.getSession(true);
        
        String roomName=request.getParameter("room");
        if (roomName==null)
            roomName="0";
        Map room = null;
        synchronized(this)
        {
            room=(Map)chatrooms.get(roomName);
            if (room==null)
            {
                room=new HashMap();
                chatrooms.put(roomName,room);
            }
        }
            
        if ("join".equals(method))
            doJoinChat(room,message,request, response);
        else if ("chat".equals(method))
            doChat(room,message,request,response);
        else if ("poll".equals(method))
            doPoll(room,request,response);
        else if ("leave".equals(method))
            doLeaveChat(room,message,request,response);
        else
            super.handle(method, message,request, response);   
    }

    /* ------------------------------------------------------------ */
    private void doJoinChat(Map room, String name, HttpServletRequest request, AjaxResponse response)
    {
        HttpSession session = request.getSession(true);
        String id = session.getId();
        if (name==null || name.length()==0)
            name="Newbie";
        Member member=null;
        
        synchronized (room)
        {
            member=(Member)room.get(id);
            if (member==null)
            {
                member = new Member(session,name);
                room.put(session.getId(),member);
            }
            else
                member.setName(name);
            
            // exists already, so just update name
            sendMessage(room,member,"has joined the chat",true);
            
            //response.objectResponse("joined", "<joined from=\""+name+"\"/>");
            sendMembers(room,response);
        }
    }
    

    /* ------------------------------------------------------------ */
    private void doLeaveChat(Map room, String name, HttpServletRequest request, AjaxResponse response)
    {
        HttpSession session = request.getSession(true);
        String id = session.getId();

        Member member=null;
        synchronized (room)
        {
            member = (Member)room.get(id);
            if (member==null)
                return;
            if ("Elvis".equals(member.getName()))
                sendMessage(room,member,"has left the building",true);
            else
                sendMessage(room,member,"has left the chat",true);
            room.remove(id);
            member.setName(null);
        }
        //response.objectResponse("left", "<left from=\""+member.getName()+"\"/>");
        sendMembers(room,response);
    }


    /* ------------------------------------------------------------ */
    private void doChat(Map room, String text, HttpServletRequest request, AjaxResponse response)
    {
        HttpSession session = request.getSession(true);
        String id = session.getId();
        
        Member member=null;
        synchronized (room)
        {
            member = (Member)room.get(id);
            
            if (member==null)
                return;
            sendMessage(room, member, text, false);
        }
    }


    /* ------------------------------------------------------------ */
    private void doPoll(Map room, HttpServletRequest request, AjaxResponse response)
    {
        HttpSession session = request.getSession(true);
        String id = session.getId();
        long timeoutMS = 60000L; 
        if (request.getParameter("timeout")!=null)
            timeoutMS=Long.parseLong(request.getParameter("timeout"));
        if (session.isNew())
            timeoutMS=1;
        
        Member member=null;
        synchronized (room)
        {
            member = (Member)room.get(id);
            if (member==null)
            {
                member = new Member(session,null);
                room.put(session.getId(),member);
            }

            Continuation continuation = ContinuationSupport.getContinuation(request, room);
            
            if (!member.hasMessages())
            {   
                if (member.getContinuation()!=null && member.getContinuation()!=continuation)
                {
                    // duplicate frames!
                    Message duplicate = new Message("System","Multiple frames/tabs/windows from same browser!",true);
                    Message action = new Message("System","Please use only one frame/tab/window",true);
                    member.addMessage(duplicate);
                    member.addMessage(action);
                    try
                    {
                        Thread.sleep(5000);
                    }
                    catch(Exception e)
                    {}
                }
                else
                {
                    member.setContinuation(continuation);
                    continuation.suspend(timeoutMS);
                }
            }
            
            if (member.getContinuation()==continuation)
                member.setContinuation(null);

            
            if (member.sendMessages(response))
                sendMembers(room,response);
        }
        
    }

    /* ------------------------------------------------------------ */
    private void sendMessage(Map room, Member member, String text, boolean alert)
    {
        Message event=new Message(member.getName(),text,alert);
        
        ArrayList invalids=null;
        synchronized (room)
        {
            Iterator iter = room.values().iterator();
            while (iter.hasNext())
            {
                Member m = (Member)iter.next();
                
                try 
                {
                    m.getSession().getAttribute("anything");
                    m.addMessage(event);
                }
                catch(IllegalStateException e)
                {
                    if (invalids==null)
                        invalids=new ArrayList();
                    invalids.add(m);
                    iter.remove();
                }
            }
        }
            
        for (int i=0;invalids!=null && i<invalids.size();i++)
        {
            Member m = (Member)invalids.get(i);
            sendMessage(room,m,"has timed out of the chat",true);
        }
    }
    
    private void sendMembers(Map room, AjaxResponse response)
    {
        StringBuffer buf = new StringBuffer();
        buf.append("<ul>\n");
        synchronized (room)
        {
            Iterator iter = room.values().iterator();
            while (iter.hasNext())
            {
                Member m = (Member)iter.next();
                if (m.getName()==null)
                    continue;
                buf.append("<li>");
                buf.append(encodeText(m.getName()));
                buf.append("</li>\n");
            }
        }
        buf.append("</ul>\n");
        response.elementResponse("members", buf.toString());
    }

    
    private static class Message
    {
        private String _from;
        private String _text;
        private boolean _alert;
        
        Message(String from, String text, boolean alert)
        {
            _from=from;
            _text=text;
            _alert=alert;
        }
        
        boolean isAlert()
        {
            return _alert;
        }
        
        public String toString()
        {
            return "<chat from=\""+_from+"\" alert=\""+_alert+"\">"+encodeText(_text)+"";
        }
        
        
        
    }

    private class Member
    {
        private HttpSession _session;
        private String _name;
        private List _messages = new ArrayList();
        private Continuation _continuation;
        
        Member(HttpSession session, String name)
        {
            _session=session;
            _name=name;
        }
        
        /* ------------------------------------------------------------ */
        /**
         * @return Returns the name.
         */
        public String getName()
        {
            return _name;
        }

        /* ------------------------------------------------------------ */
        /**
         * @param name The name to set.
         */
        public void setName(String name)
        {
            _name = name;
        }

        /* ------------------------------------------------------------ */
        /**
         * @return Returns the session.
         */
        public HttpSession getSession()
        {
            return _session;
        }


        /* ------------------------------------------------------------ */
        /**
         * @param continuation The continuation to set.
         */
        public Continuation getContinuation()
        {
            return _continuation;
        }
        
        /* ------------------------------------------------------------ */
        /**
         * @param continuation The continuation to set.
         */
        public void setContinuation(Continuation continuation)
        {
            if (continuation!=null && _continuation!=null && _continuation!=continuation)
                _continuation.resume();
            _continuation=continuation;
        }
        
        /* ------------------------------------------------------------ */
        public void addMessage(Message event)
        {
            if (_name==null)
                return;
            _messages.add(event);
            if (_continuation!=null)
                _continuation.resume();
        }

        /* ------------------------------------------------------------ */
        public boolean hasMessages()
        {
            return _messages!=null && _messages.size()>0;
        }
        
        /* ------------------------------------------------------------ */
        public void rename(Map room,String name)
        {
            String oldName = getName();
            setName(name);
            if (oldName!=null)
                ChatFilter.this.sendMessage(room,this,oldName+" has been renamed to "+name,true);
        }

        /* ------------------------------------------------------------ */
        public boolean sendMessages(AjaxResponse response)
        {
            synchronized (this)
            {
                boolean alerts=false;
                for (int i=0;i<_messages.size();i++)
                {
                    Message event = (Message)_messages.get(i);
                    response.objectResponse("chat", event.toString());
                    alerts |= event.isAlert();
                }
                _messages.clear();
                return alerts;
            }
        }

    }
}