java聊天室程序，有客户端和服务器端，可私聊，服务器提示上下线状态

客户端: 
package chatroom; 
import java.awt.*; 
import java.awt.event.*; 
import java.net.*; 
import java.io.*; 
import javax.swing.*; 
public class client extends JFrame implements ActionListener,Runnable{ 
JPanel conn,text,send; 
JLabel name,sendto; 
JComboBox list; 
JButton con,snd,clear; 
JTextArea talk; 
JTextField who,say; 
JScrollPane jsp; 
Socket client; 
InputStream is; 
OutputStream os; 
PrintStream ps; 
BufferedReader br; 
String receive,yousay; 
Thread th; 
DataInputStream dis; 
Double tof; 


client() 
{ 
super("聊天室客户端"); 
this.setSize(800,600); 

this.setResizable(false); 
conn=new JPanel(); 
text=new JPanel(); 
send=new JPanel(); 
this.getContentPane().add(conn); 
conn.setBounds(0, 0, this.getWidth(),50); 
name=new JLabel("姓名:"); 
who=new JTextField(); 
con=new JButton("连接"); 
conn.setLayout(null); 
conn.add(name); 
name.setBounds(30, 10, 50, 25); 
conn.add(who); 
who.setBounds(80, 10, 150, 25); 
conn.add(con); 
con.setBounds(250,10, 60, 25); 


this.getContentPane().add(text); 
text.setBounds(0,50,this.getWidth(),450); 
text.setLayout(new BorderLayout()); 
jsp=new JScrollPane(); 
talk=new JTextArea(); 
jsp.getViewport().setView(talk); 
text.add(jsp,"Center"); 
talk.setLineWrap(true); 


this.getContentPane().add(send); 
send.setLayout(null);