1.创建包

.服务界面 

package yiduiy;import java.awt.BorderLayout;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Set;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;public class fuwumianban extends JFrame {private JTextArea ta_info;private ServerSocket server; // 声明ServerSocket对象private Socket socket; // 声明Socket对象socketprivate Hashtable<String, Socket> map = new Hashtable<String, Socket>();// 用于存储连接到服务器的用户和客户端套接字对象public void createSocket() {try {server = new ServerSocket(1978);while (true) {ta_info.append("等待新客户连接......\n");socket = server.accept();// 创建套接字对象ta_info.append("客户端连接成功。" + socket + "\n");new ServerThread(socket).start();// 创建并启动线程对象}} catch (IOException e) {e.printStackTrace();}}class ServerThread extends Thread {Socket socket;public ServerThread(Socket socket) {this.socket = socket;}public void run() {try {BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));// 创建输入流对象while (true) {String info = in.readLine();// 读取信息String key = "";if (info.startsWith("用户：")) {// 添加登录用户到客户端列表key = info.substring(3, info.length());// 获得用户名并作为键使用map.put(key, socket);// 添加键值对Set<String> set = map.keySet();// 获得集合中所有键的Set视图Iterator<String> keyIt = set.iterator();// 获得所有键的迭代器while (keyIt.hasNext()) {String receiveKey = keyIt.next();// 获得表示接收信息的键Socket s = map.get(receiveKey);// 获得与该键对应的套接字对象PrintWriter out = new PrintWriter(s.getOutputStream(), true);// 创建输出流对象Iterator<String> keyIt1 = set.iterator();// 获得所有键的迭代器while (keyIt1.hasNext()) {String receiveKey1 = keyIt1.next();// 获得键，用于向客户端添加用户列表out.println(receiveKey1);// 发送信息out.flush();// 刷新输出缓冲区}}} else {// 转发接收的消息key = info.substring(info.indexOf("：发送给：") + 5, info.indexOf("：的信息是："));// 获得接收方的key值,即接收方的用户名String sendUser = info.substring(0, info.indexOf("：发送给："));// 获得发送方的key值,即发送方的用户名Set<String> set = map.keySet();// 获得集合中所有键的Set视图Iterator<String> keyIt = set.iterator();// 获得所有键的迭代器while (keyIt.hasNext()) {String receiveKey = keyIt.next();// 获得表示接收信息的键if (key.equals(receiveKey)&& !sendUser.equals(receiveKey)) {// 如果是发送方，但不是用户本身Socket s = map.get(receiveKey);// 获得与该键对应的套接字对象PrintWriter out = new PrintWriter(s.getOutputStream(), true);// 创建输出流对象out.println("MSG:"+info);// 发送信息out.flush();// 刷新输出缓冲区}}}}} catch (IOException e) {ta_info.append(socket + "已经退出。\n");}}}public static void main(String args[]) {fuwumianban frame = new fuwumianban();frame.setVisible(true);frame.createSocket();}public fuwumianban() {super();setTitle("多个用户聊天");setBounds(100, 100, 385, 266);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);final JScrollPane scrollPane = new JScrollPane();getContentPane().add(scrollPane, BorderLayout.CENTER);ta_info = new JTextArea();scrollPane.setViewportView(ta_info);}
}

 客户界面

package yiduiy;import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;public class kehu extends JFrame {private JTextField tf_newUser;private JList user_list;private JTextArea ta_info;private JTextField tf_send;PrintWriter out;// 声明输出流对象private boolean loginFlag = false;// 为true时表示已经登录，为false时表示未登录/*** Launch the application* * @param args*/public static void main(String args[]) {EventQueue.invokeLater(new Runnable() {public void run() {try {kehu frame = new kehu();frame.setVisible(true);frame.createClientSocket();// 调用方法创建套接字对象} catch (Exception e) {e.printStackTrace();}}});}public void createClientSocket() {try {Socket socket = new Socket("127.0.0.1", 1978);// 创建套接字对象out = new PrintWriter(socket.getOutputStream(), true);// 创建输出流对象new ClientThread(socket).start();// 创建并启动线程对象} catch (UnknownHostException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}class ClientThread extends Thread {Socket socket;public ClientThread(Socket socket) {this.socket = socket;}public void run() {try {BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));// 创建输入流对象DefaultComboBoxModel model = (DefaultComboBoxModel) user_list.getModel();// 获得列表框的模型while (true) {String info = in.readLine().trim();// 读取信息if (!info.startsWith("MSG:")) {boolean itemFlag = false;// 标记是否为列表框添加列表项，为true不添加，为false添加for (int i = 0; i < model.getSize(); i++) {if (info.equals((String) model.getElementAt(i))) {itemFlag = true;}}if (!itemFlag) {model.addElement(info);// 添加列表项} else {itemFlag = false;}} else {ta_info.append(info + "\n");// 在文本域中显示信息if (info.equals("88")) {break;// 结束线程}}}} catch (IOException e) {e.printStackTrace();}}}private void send() {if (!loginFlag) {JOptionPane.showMessageDialog(null, "请先登录。");return;}String sendUserName = tf_newUser.getText().trim();String info = tf_send.getText();// 获得输入的信息if (info.equals("")) {return;// 如果没输入信息则返回，即不发送}String receiveUserName = (String) user_list.getSelectedValue();// 获得接收信息的用户String msg = sendUserName + "：发送给：" + receiveUserName + "：的信息是： "+ info;// 定义发送的信息if (info.equals("88")) {System.exit(0);// 如果没输入信息是88，则退出}out.println(msg);// 发送信息out.flush();// 刷新输出缓冲区tf_send.setText(null);// 清空文本框}/*** Create the frame*/public kehu() {super();setTitle("多个用户聊天");setBounds(100, 100, 385, 288);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);final JPanel panel = new JPanel();getContentPane().add(panel, BorderLayout.SOUTH);final JLabel label = new JLabel();label.setText("输入聊天内容：");panel.add(label);tf_send = new JTextField();tf_send.addActionListener(new ActionListener() {public void actionPerformed(final ActionEvent e) {send();// 调用方法发送信息}});tf_send.setPreferredSize(new Dimension(180, 25));panel.add(tf_send);final JButton button = new JButton();button.addActionListener(new ActionListener() {public void actionPerformed(final ActionEvent e) {send();// 调用方法发送信息}});button.setText("发  送");panel.add(button);final JSplitPane splitPane = new JSplitPane();splitPane.setDividerLocation(100);getContentPane().add(splitPane, BorderLayout.CENTER);final JScrollPane scrollPane = new JScrollPane();splitPane.setRightComponent(scrollPane);ta_info = new JTextArea();scrollPane.setViewportView(ta_info);final JScrollPane scrollPane_1 = new JScrollPane();splitPane.setLeftComponent(scrollPane_1);user_list = new JList();user_list.setModel(new DefaultComboBoxModel(new String[] { "" }));scrollPane_1.setViewportView(user_list);final JPanel panel_1 = new JPanel();getContentPane().add(panel_1, BorderLayout.NORTH);final JLabel label_1 = new JLabel();label_1.setText("输入用户名称：");panel_1.add(label_1);tf_newUser = new JTextField();tf_newUser.setPreferredSize(new Dimension(180, 25));panel_1.add(tf_newUser);final JButton button_1 = new JButton();button_1.addActionListener(new ActionListener() {public void actionPerformed(final ActionEvent e) {if (loginFlag) {JOptionPane.showMessageDialog(null, "在同一窗口只能登录一次。");return;}String userName = tf_newUser.getText().trim();// 获得登录用户名out.println("用户：" + userName);// 发送登录用户的名称out.flush();// 刷新输出缓冲区tf_newUser.setEnabled(false);loginFlag = true;}});button_1.setText("登  录");panel_1.add(button_1);}
}