A must-see Java program

Program//Program name: Telnetapp.java

Import java.applet.*;
Import java.awt.*;
Import java.io.*;
Import java.net.*;
Import java.util.*;

public class Telnetapp extends Applet implements Runnable
{
Declaring a member variable

Thread client;
TextArea log;

TextField hostname;
TextField userid;
TextField password;
Label Hname;
Label uid;
Label PSD;

Button Connect;
Button bye;

int wanttime;
Boolean logged;

Socket socket =null;
PrintStream OS;
DataInputStream is;

Public Telnetapp ()
{
Resize (400,300);
SetLayout (New BorderLayout ());
Panel p1=new Panel ();
Log =new TextArea (10,80);
Log.seteditable (TRUE);
P1.add (log);
Add ("North", p1);

Panel p2=new Panel ();
P2.add (hname=new Label ("Hostname"));
P2.add (hostname =new TextField (20));
P2.add (uid= new Label ("Userid:"));
P2.add (userid =new TextField (10));
P2.add (PSD =new Label ("Password:"));
P2.add (Password =new TextField (10));
Password.setechocharacter (' * ');

Add ("Center", p2);

Panel p3=new Panel ();
P3.add (Connect =new button ("Connect"));
P3.add (Bye =new button ("Bye"));
Bye.disable ();
Add ("South", p3);

logged = false;
}

public void Run ()
{
String Fromserver=null;
byte b[]=new byte[3];
b[0]= (Byte) ' n ';
while (true) {
if ((Fromserver =getdate ())!= null)
Log.appendtext (fromserver + "\ n");
if (Wanttime <0) {
Bye ();
Break
}
if (logged) {
Delay (60*1000);
Log.settext ("");
Wanttime-= 1;
SendData (b,1);
}
}
}

Establish a host connection

Private Boolean Connecthost (String hostName)
{
try{
Socket =new socket (hostname,23);
Os =new printstream (Socket.getoutputstream ());
is =new DataInputStream (Socket.getinputstream ());
}catch (Unknownhostexception e) {
Log.settext ("Trying to connect to unknown host:" +e);
return false;
}catch (Exception e) {
Log.settext ("Exception:" +e);
return false;
}
return true;
}

Receive information

String GetDate ()
{
String fromserver;
int Len;
byte b[]=new byte[1000];
try{
Fromserver = "";
Len =is.read (b);

Fromserver + = new String (b,0);
}catch (Exception e) {
Log.settext ("Exception:" +e);
return null;
}
return fromserver;
}

Send a message

Boolean SendData (byte B[],int len)
{
try{
Os.write (B,0,len);
Os.flush ();
}catch (Exception e) {
Log.settext ("Exception:" + e);
return false;
}
return true;
}

Close connection

void Closesocket ()
{
try{
Os.close ();
Is.close ();
Socket.close ();
socket = NULL;
}catch (Exception e) {
Log.settext ("Exception:" +e);
}
}

void ToByte (byte[] b,string s)
{
int i;

For (I=0;i<s.length (); i++)
B[i]= (Byte) S.charat (i);
B[i] = 13;
b[i+1]=10;
}

void Negotiate ()
{
byte b[]=new byte[20];
B[0] =-1;b[1]=-5;b[2]=24;
SendData (b,3);
Delay (400);

B[0] =-1;b[1]=-6;b[2]=24;
B[3] =0;b[4]= (byte) ' D '; b[5]= (byte) ' E ';
B[6] = (byte) ' C '; b[7]= (byte) '-'; b[8]= (byte) ' V ';
B[9] = (byte) ' T '; b[10]= (byte) ' 1 '; b[11]= (byte) ' 0 ';
B[12] = (byte) ' 0 '; b[13]= (byte) -1;b[14]=-16;
SendData (b,15);
Delay (400);

Other options
B[0] =-1;b[1]=-3;b[2]=1;
b[3]=-1;b[4]=-3;b[5]=3;
b[6]=-1;b[7]=-3;b[8]=31;
b[9]=-1;b[10]=-4;b[11]=-56;
B[12]=-1;b[13]=-5;b[14]=1;
SendData (b,15);
Delay (400);

Login BBS
ToByte (b, "BBS");
SendData (b,5);
Delay (400);
}

void Login (String userid,string password)
{
BYTE b[] =new byte[20];
ToByte (B,userid);
SendData (B,userid.length () +2);
Delay (400);

ToByte (B,password);
SendData (B,password.length () +2);
Delay (400);
}

Boolean Enter ()
{
if (Connecthost (Hostname.gettext (). Trim ()))
{
Log.settext ("connected\n");

Negotiate ();
Delay (400);

Login (Userid.gettext (). Trim (), Password.gettext (). Trim ());
return true;
else return false;
}

void Tomainmenu ()
{
byte b[]=new byte[20];
for (int i=0;i<6;i++)
{
ToByte (b, "");
SendData (b,2);
}

for (int i=0;i<1;i++)
{
B[0] = (byte) ' Q ';
SendData (b,1);
Delay (200);
}
}

void Bye ()
{
BYTE b[]= new byte[20];

for (int i=0;i<10;i++)
{
b[0]= (byte) ' Q ';
SendData (b,1);
Delay (300);
}

b[0]= (Byte) ' G ';
SendData (b,1);
Delay (300);
for (int i=0;i<6;i++)
{
ToByte (b, "");
SendData (b,2);
Delay (300);
}
Client.stop ();
Client=null;
Closesocket ();
Connect.enable ();
Bye.disable ();
}

void delay (int millisecond)
{
try{
Thread.Sleep (millisecond);
}catch (Interruptedexception e) {
}
}

Public boolean action (Event e,object Arg)
{
Switch (e.id) {
Case Event.action_event:
if (E.target = connect)
{
Wanttime = 20;
Connect.disable ();
Bye.enable ();
Client =new Thread (this);
Client.start ();
if (enter ())
Tomainmenu ();
Logged =true;
}else if (e.target = = bye)
Bye ();
}
return true;
}

public void Destroy () {
}
public void Paint (Graphics g) {}
public void Start () {}
public void Stop () {
}
}