Problems with developing a chatroom
Hi all,
I am new to jsp and am learning. I need some help. I am developing a chat room application. I am using AJAX to update the screen. Since JSP caches the data, I am using a servlet code for AJAX alone. For others I use JSP as the server coding.
Suppose consider i am logging in as 'user1', I am able to receive other users message only if I trigger any event.
Can you please help me to get others message automatically? Here is my code:
//This jsp code validates the user and provides the chat room screen...
<%--Login validation--%>
<%@ page language="java" %>
<%@ page import="java.sql.*" %>
<%@ page contentType="text/html" %>
<html>
<head>
<title>Login Result</title>
<script src="http://localhost:8080/ChatRoom/ChatScript.js" type="text/javascript"></script>
</head>
<body>
<%
String uid=request.getParameter("id");
String pwd=request.getParameter("pwd");
String tmp_uid="";
String tmp_pwd="";
String welcomeName="";
String onlineMembers="";
String buddyList="";
{
Connection con;
PreparedStatement ps;
ResultSet rs;
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("jdbc:odbc:LoginDB");
String str="select * from login where uname=?";
ps=con.prepareStatement(str);
ps.setString(1,uid);
rs=ps.executeQuery();
while(rs.next())
{
tmp_uid = rs.getString("uname");
tmp_pwd = rs.getString("pwd");
welcomeName = rs.getString("fname");
}
if(uid.equals(tmp_uid)&&pwd.equals(tmp_pwd))
{
Cookie ck = new Cookie("user",uid);
response.addCookie(ck);
try{
String setStatus="update login set status='1' where uname=?";
ps=con.prepareStatement(setStatus);
ps.setString(1,uid);
ps.executeQuery();
}catch(Exception e){}
%>
<form method="post" action="logout.jsp">
<%
out.print("Welcome "+welcomeName+" !");
//out.print("<input type=\"hidden\" name=\"username\" value="+uid+">");
%>
<input type="submit" value="Logout"></form><hr>
<%
String checkStatus="select uname from login where status=?";
ps=con.prepareStatement(checkStatus);
ps.setString(1,"1");
rs=ps.executeQuery();
while(rs.next())
{
tmp_uid = rs.getString("uname");
onlineMembers=onlineMembers.concat(tmp_uid+"\n");
}
String friends ="select * from vijay";
ps=con.prepareStatement(friends);
rs=ps.executeQuery();
while(rs.next())
{
String buddy = rs.getString("buddy");
buddyList = buddyList.concat(buddy+"\n");
}
%>
<form action="#" name="chatForm">
Buddy List
<pre><textarea cols=19 rows=20 readonly="readonly" name="BuddyList">
<%
out.println(buddyList);
%>
</textarea> <textarea cols=72 rows=20 readonly="readonly" name="ReceiveText"></textarea> <textarea cols=19 rows=20 readonly="readonly" name="OnlineList">
<%
out.println(onlineMembers);
%>
</textarea></pre>
Type your text here!
<pre><b><textarea cols=90 rows=3 name="SendText"></textarea></b><input type="button" value=" Send " onclick="sendRequest(SendText.value,user.value)"/></pre>
<%
out.print("<input type=\"hidden\" name=\"user\" value="+uid+">");
%>
</form>
<%
}
else
{
%>
<jsp:include page="INVALID_USER_HOME.HTML" flush="true"/>
<%
}
con.close();
}
%>
</body>
</html>
//This is script for AJAX
var request;
var address;
function getRequestObject()
{
if (window.ActiveXObject)
{
return(new ActiveXObject("Microsoft.XMLHTTP"));
}
else if (window.XMLHttpRequest)
{
return(new XMLHttpRequest());
}
else
{
return(null);
}
}
function sendRequest(str,username)
{
address = "http://localhost:8080/ChatServlet/AjaxServer";
address = address+"?text="+str;
address = address+"&name="+username;
request = getRequestObject();
request.onreadystatechange = handleResponse;
if((str.length>0)&&(username.length>0))
{
request.open("GET",address,true);
request.send(null);
}
setTimeout("sendRequest()",500);
}
function handleResponse()
{
if ((request.readyState == 4)&&(request.status == 200))
{
document.chatForm.ReceiveText.value = request.responseText;
document.chatForm.SendText.value = "";
}
}
//This is the servlet for servicing the AJAX requests:
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ChatServlet extends HttpServlet
{
PrintWriter out;
static String message = "";
String sendText = "";
String name = "";
public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException, IOException
{
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
response.setContentType("text/html");
sendText = request.getParameter("text");
name = request.getParameter("name");
PrintWriter out = response.getWriter();
java.util.Date d = new java.util.Date();
String date = String.format("(%tr)",d);
message = message.concat(date+name+" : "+sendText+"\n");
out.println(message);
}
}
