网络应用模式主要有：

• 主机/终端模式：集中计算，集中管理；
• 客户机/服务器（Client/Server,简称C/S）模式：分布计算，分布管理；
• 浏览器/服务器模式：利用Internet跨平台。

.*;import java.io.*;import java.awt.*;import javax.swing.*;import java.awt.event.*;import java.applet.*;public class Aclient extends Applet implements Runnable,ActionListener{ JButton button; JTextField textF; JTextArea textA; Socket socket; Thread thread; DataInputStream in; DataOutputStream out; public void init(){ setBackground(new Color(120,153,137)); setLayout(new BorderLayout()); Button = new JButton(“发送信息”); textF = new JTextField(20); textA = new JTextArea(20,30); setSize(450,350); JPanel p = new JPanel(); p.add(textF); p.add(button); add(textA,”Center”); add(p,”South”); button.addActionListener(this); } public void start(){ try{ socket = new Socket(this.getCodeBase().getHost(),4441); in = new DataInputStream(socket.getInputStream()); out = new DataOutputStream(socket.getOutputStream()); }catch(IOException e){} if(thread==null){ thread = new Thread(this); thread.setPriority(Thread.MIN_PRIORITY); thread.start(); } } public void run(){ String s = null; while(true){ try{ s = in.readUTF(); }catch(IOException e){} if(s.equals(“结束”)){ try{ socket.close();break; }catch(IOException e){} }else texA.append(s + “\n”); } } public void actionPerformed(ActionEvent e){ if(e.getSource()==button){ String s = textF.getText(); if(s! = null){ try{ out.writeUTF(s); }catch(IOException e1){} } else{ try{ out.writeUTF(“请说话”); }catch(IOException e1){} } } }}