heardfirst裡面有基於tcp/ip協議的socket聊天程式，這裡做一下記錄
SimpleChatClient客戶端類

public class SimpleChatClientA {
    JTextArea incoimg;
    JTextField outgoing;
    BufferedReader reader;
    PrintWriter writer;
    Socket sock;

    //建立了一個視窗介面
    public void go(){
        JFrame frame = new JFrame("Ludicrously Simple Chat Client"
 
);
        JPanel mainPanel = new JPanel();
        incoimg = new JTextArea(15, 50);
        incoimg.setLineWrap(true);
        incoimg.setWrapStyleWord(true);
        incoimg.setEditable(false);
        JScrollPane qScroller = new JScrollPane(incoimg);
        qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        qScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        outgoing = new
 
 JTextField(20);
        JButton sendButton = new JButton("Send");
        sendButton.addActionListener(new SendButtonListener());
        mainPanel.add(qScroller);
        mainPanel.add(outgoing);
        mainPanel.add(sendButton);
        setUpNetworking();

        Thread readerThread = new Thread(new
 
 IncomingReader());
        readerThread.start();

        frame.getContentPane().add(BorderLayout.CENTER, mainPanel);
        frame.setSize(400, 500);
        frame.setVisible(true);
    }
    //初始化
    private void setUpNetworking(){
        try {
            sock = new Socket("127.0.0.1", 5000);
            writer = new PrintWriter(sock.getOutputStream());
            reader = new BufferedReader(new InputStreamReader(sock.getInputStream()));
            System.out.println("networking established");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //監聽button
    public class SendButtonListener implements ActionListener{
        public void actionPerformed(ActionEvent ev) {
            writer.println("B"+outgoing.getText());
            writer.flush();
            outgoing.setText("");
            outgoing.requestFocus();
        }
    }

    public class IncomingReader implements Runnable{
        @Override
        public void run() {
            String message;
            try {
                while((message=reader.readLine())!=null){
                    System.out.println("read:"+message);
                    incoimg.append(message+"\n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    } 

    public static void main(String[] args) {
        new SimpleChatClientA().go();
    }
}

伺服器端

public class VerySimpleChatServer {
    private volatile ArrayList clientOutputStreams;

    public class ClientHandler implements Runnable{
        BufferedReader reader;
        Socket sock;
        public ClientHandler(Socket clientSocket){
            try {
                sock = clientSocket;
                reader = new BufferedReader(new InputStreamReader(sock.getInputStream()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        @Override
        public void run() {
            String message;
            try {
                while((message=reader.readLine())!=null){
                    System.out.println("reader:"+message);
                    tellEveryone(message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    public void go(){
        clientOutputStreams = new ArrayList();
        try {
            synchronized(clientOutputStreams){
                ServerSocket serverSock = new ServerSocket(5000);
                while(true){
                        Socket clientSocket = serverSock.accept();
                        PrintWriter write = new PrintWriter(clientSocket.getOutputStream());
                        clientOutputStreams.add(write);

                        Thread t= new Thread(new ClientHandler(clientSocket));
                        t.start();
                        System.out.println("got a connection");
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public void tellEveryone(String message){
        Iterator it = clientOutputStreams.iterator();
        while(it.hasNext()){
            PrintWriter write = (PrintWriter) it.next();
            write.println(message);
            write.flush();
        }
    }

    public static void main(String[] args) {
        new VerySimpleChatServer().go();
    }
}