how to run telnet program
find ip address by typing ipconfig

1. Run java mserver // server program in one to many chat
2. Run Telnet
type following and press enter
open 192.168.1.37 4000

telnet

====
Telnet program

===
import java.net.*;
import java.io.*;
import java.util.*;
public class telnet extends Thread
{
static Socket cs=null;
static PrintWriter pw=null;
static BufferedReader br=null,in=null;
public static void main(String args[]) throws Exception
{
System.out.println("TELNET");
in=new BufferedReader(new InputStreamReader(System.in));
String command=in.readLine();
StringTokenizer st=new StringTokenizer(command);
String service=st.nextToken();
if(service.equals("open"))
{
String address=st.nextToken();
String port=st.nextToken();
if(!port.equals("null"))
open(address,port);
}
else if(service.equals("quit"))System.exit(0);
else System.out.println("invalid,try help");
}
static void open(String address,String port) throws Exception
{
try
{
if(address.equals("null"))
{
System.out.println("Specify correct addresss");
return;
}
System.out.println("Waiting for a connection");
cs=new Socket(address,Integer.parseInt(port));
br=new BufferedReader(new InputStreamReader(cs.getInputStream()));
pw=new PrintWriter(cs.getOutputStream(),true);
System.out.println("Connection Established");
new SendData(pw,in).start();
new ReceiveData(br).start();
}
catch(Exception e)
{
System.out.println("Unable to connect");
}
}

static class SendData extends telnet
{
PrintWriter pw=null;
BufferedReader in=null;
SendData(PrintWriter p,BufferedReader b)
{
pw=p;
in=b;
}
public void run()
{
while(true)
{
try
{
pw.println(in.readLine());
}
catch(IOException e){}
}
}
}
static class ReceiveData extends telnet
{
BufferedReader br=null;
ReceiveData(BufferedReader b)
{ br=b;
}
public void run()
{
while(true)
{
try
{
System.out.println(br.readLine());
}
catch(IOException e){}
}
}
}
}

random number between 0 and 2
===============================
import java.math.*;
public class k
{

public static void main(String a[])
{
Double k;

k=Math.random()*1000;
int s=k.intValue();
s= s%3;
System.out.println(" s is "+s);
}

}

DB CLIENT
==========
import java.io.*;
import java.net.*;
public class DBClient
{
static Socket cs=null;
public static void main(String args[]) throws IOException
{
try
{
cs=new Socket("localhost",1090);
}
catch(Exception e){}
System.out.println("Enter the code");
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
BufferedReader in=new BufferedReader(new InputStreamReader(cs.getInputStream()));
PrintWriter out=new PrintWriter(cs.getOutputStream(),true);
System.out.println(in.readLine());
String user=null,pass=null;
while(true)
{
System.out.println("commands:1:insert 2:update 3:select 4:delete 5:Exit");
int choice=Integer.parseInt(stdin.readLine());
switch(choice)
{
case 1:System.out.println("Enter username and password to be inserted");
user=stdin.readLine();
pass=stdin.readLine();
out.println("1");
out.println(user);
out.println(pass);
System.out.println(in.readLine());
break;
case 2:System.out.println("Enter username and new password to be updates");
user=stdin.readLine();
pass=stdin.readLine();
out.println("2");
out.println(user);
out.println(pass);
System.out.println(in.readLine());
break;
case 3:System.out.println("enter username whose password is needed");
user=stdin.readLine();
out.println("3");
out.println(user);
System.out.println(in.readLine());
break;
case 4:System.out.println("enter username of person whose details has to be deleted?");
user=stdin.readLine();
out.println("4");
out.println(user);
System.out.println(in.readLine());
break;
case 5: System.exit(1);
default:break;
}
}
}
}

DB SERVER
==========
import java.io.*;
import java.sql.*;
import java.net.*;
public class DBServer
{
static Connection con;
static Statement st1,st2;
static ResultSet rs1;

static ResultSetMetaData rsmd;
static String[] rec=new String[10];
static ServerSocket ss=null;
static Socket s=null;
public static void main(String args[])
{
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("jdbc:odbc:irk","system","bvrice");

st1=con.createStatement();
st2=con.createStatement();
System.out.println("Done");
}
catch(Exception e)
{
System.out.println("Error establishing connection"+e);
}
String output=" ",qry=" ";
try
{
ss=new ServerSocket(1090);
System.out.println("Server");
s=ss.accept();
BufferedReader in=new BufferedReader(new InputStreamReader(s.getInputStream()));
PrintWriter out=new PrintWriter(s.getOutputStream(),true);
out.println("welcome to DBServer");
while(true)
{
int choice=Integer.parseInt(in.readLine());
String usr=null,pass=null;
int c=0;
switch(choice)
{
case 1:usr=in.readLine();
pass=in.readLine();
c=st1.executeUpdate("insert into userinfo values('"+usr+"','"+pass+"')");
if(c==1) out.println("Date inserted succcessfully");
break;
case 2: usr=in.readLine();
pass=in.readLine();
System.out.println("username="+usr+"password="+pass);
rs1=st1.executeQuery("select * from userinfo where userid='"+usr+"'");
while(rs1.next())
{
c=st1.executeUpdate("Update userinfo set password='"+pass+"' where userid ='"+usr+"'");
}
if(c==1) out.println("password updated for the given username");
else
out.println("update not possible");
break;
case 3:usr=in.readLine();
rs1=st1.executeQuery("select * from userinfo where userid='"+usr+"'");
rs1.next();
System.out.println(rs1.getString(1)+" "+rs1.getString(2));
out.println(rs1.getString(2));
break;
case 4:usr=in.readLine();
c=st1.executeUpdate("delete userinfo where userid='"+usr+"'");
if(c==1) out.println("userinformation for the following userid"+usr+"is deleted");
break;
default:break;
}
}
}
catch(Exception ie)
{}
}
}