基于此示例，这是一个使用Swing的简单网络客户端/服务器对。请注意与正确同步有关的一些问题：GUI本身是使用事件分配线程构建的
invokeLater()。此外，代码还依赖的线程安全性
append()。最后，它结合了文章Text Area Scrolling中的一个方便提示。
更新：在Java 7中，
append()不再标记为线程安全；
invokeLater()用于
display()序列更新。
package net;import java.awt.*;import java.awt.event.*;import java.io.*;import java.net.*;import java.util.Scanner;import javax.swing.*;import javax.swing.text.DefaultCaret;public class Echo implements ActionListener, Runnable { private static final String HOST = "127.0.0.1"; private static final int PORT = 12345; private final Jframe f = new Jframe(); private final JTextField tf = new JTextField(25); private final Jtextarea ta = new Jtextarea(15, 25); private final JButton send = new JButton("Send"); private volatile PrintWriter out; private Scanner in; private Thread thread; private Kind kind; public static enum Kind { Client(100, "Trying"), Server(500, "Awaiting"); private int offset; private String activity; private Kind(int offset, String activity) { this.offset = offset; this.activity = activity; } } public Echo(Kind kind) { this.kind = kind; f.setTitle("Echo " + kind); f.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); f.getRootPane().setDefaultButton(send); f.add(tf, BorderLayout.NORTH); f.add(new JScrollPane(ta), BorderLayout.CENTER); f.add(send, BorderLayout.SOUTH); f.setLocation(kind.offset, 300); f.pack(); send.addActionListener(this); ta.setLineWrap(true); ta.setWrapStyleWord(true); DefaultCaret caret = (DefaultCaret) ta.getCaret(); caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE); display(kind.activity + HOST + " on port " + PORT); thread = new Thread(this, kind.toString()); } public void start() { f.setVisible(true); thread.start(); } //@Override public void actionPerformed(ActionEvent ae) { String s = tf.getText(); if (out != null) { out.println(s); } display(s); tf.setText(""); } //@Override public void run() { try { Socket socket; if (kind == Kind.Client) { socket = new Socket(HOST, PORT); } else { ServerSocket ss = new ServerSocket(PORT); socket = ss.accept(); } in = new Scanner(socket.getInputStream()); out = new PrintWriter(socket.getOutputStream(), true); display("Connected"); while (true) { display(in.nextLine()); } } catch (Exception e) { display(e.getMessage()); e.printStackTrace(System.err); } } private void display(final String s) { EventQueue.invokeLater(new Runnable() { //@Override public void run() { ta.append(s + "u23CEn"); } }); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { //@Override public void run() { new Echo(Kind.Server).start(); new Echo(Kind.Client).start(); } }); }}
