package wzb; import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.Panel;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.KeyEvent;import java.util.Random; import javax.swing.ImageIcon;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JOptionPane;import javax.swing.JPasswordField;import javax.swing.JTextField; public class Login extends JFrame implements ActionListener { String userName; String password; String captcha; public static String randomcaptcha;  public JLabel logoLabel, userNameLabel, passwordLabel, captchaLabel; public JTextField userNameInput, captchaInput; public JPasswordField passwordInput; public JButton login, logout,change; public Panel panel;  public Login() {  setTitle("µÇ¼½çÃæ");  setSize(400, 300);  setLocationRelativeTo(null);  init();  setVisible(true);  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  setResizable(false); }  public void init() {  setLayout(null);  // logoLabel= new JLabel();  // logoLabel.setIcon(new ImageIcon("E://eclipse//student3//welcome.gif"));  logoLabel = new JLabel(new ImageIcon("welcome.gif"));  logoLabel.setBounds(125, 10, 150, 70);  add(logoLabel);   userNameLabel = new JLabel("Óû§Ãû:");  userNameLabel.setBounds(90, 90, 60, 40);  add(userNameLabel);  userNameInput = new JTextField();  userNameInput.setBounds(150, 100, 150, 20);  add(userNameInput);   passwordLabel = new JLabel("ÃÜ¡¡Âë:");  passwordLabel.setBounds(90, 120, 60, 40);  add(passwordLabel);  passwordInput = new JPasswordField();  passwordInput.setBounds(150, 130, 150, 20);  add(passwordInput);   captchaLabel = new JLabel("ÑéÖ¤Âë:");  captchaLabel.setBounds(90, 150, 60, 40);  add(captchaLabel);  captchaInput = new JTextField();  captchaInput.setBounds(150, 160, 70, 20);  add(captchaInput);   panel = new PanelDemo();  panel.setBounds(220, 160, 80, 20);  add(panel);        change = new JButton("»»Ò»»»");  change.setBounds(300, 160, 80, 20);  change.setContentAreaFilled(false);  change.setBorderPainted(false);  add(change);   login = new JButton("µÇ¼£¨L£©", new ImageIcon("login.gif"));  login.setBounds(70, 200, 120, 30);  login.setMnemonic(KeyEvent.VK_L);  add(login);  logout = new JButton("Í˳ö£¨X£©", new ImageIcon("exit.gif"));  logout.setBounds(210, 200, 120, 30);  logout.setMnemonic(KeyEvent.VK_X);  add(logout);   userNameInput.addActionListener(this);  passwordInput.addActionListener(this);  captchaInput.addActionListener(this);   login.addActionListener(this);  logout.addActionListener(this);  change.addActionListener(this); }  public void actionPerformed(ActionEvent e) {   userName = userNameInput.getText();  password = new String(passwordInput.getPassword());  captcha = captchaInput.getText();     if (e.getSource() == change) {   panel.repaint();  }  if (e.getSource() == login) {   if ((userName.equals("w")) && (password.equals("w"))) {    if (captcha.equals(randomcaptcha)) {     JOptionPane.showMessageDialog(this, "»¶Ó­µÇ½!");    } else {     JOptionPane.showMessageDialog(this, "ÑéÖ¤Âë´íÎó!");     panel.repaint();    }   } else {    JOptionPane.showMessageDialog(this, "Óû§Ãû»òÃÜÂë´íÎó!");   }  }  if (e.getSource() == logout) {   JOptionPane.showMessageDialog(this, "»¶Ó­Ï´ÎÔÙÀ´£¡");   //System.exit(0);   dispose();  } } public static void main(String[] args) {  new Login(); }}class PanelDemo extends Panel {  public void paint(Graphics g) {  int width = 80;  int height = 20;  g.setColor(Color.LIGHT_GRAY);  g.fillRect(0, 0, width, height);  g.setColor(Color.BLACK);  g.drawRect(0, 0, width, height);  Random rd = new Random();  for (int i = 0; i < 100; i++) {   int x = rd.nextInt(width) - 2;   int y = rd.nextInt(height) - 2;   g.setColor(Color.RED);   g.drawOval(x, y, 2, 2);  }  g.setFont(new Font("ºÚÌå", Font.BOLD, 20));  g.setColor(Color.BLUE);  char[] c = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();  StringBuffer sb = new StringBuffer();  for (int i = 0; i < 4; i++) {   int index = rd.nextInt(c.length);   sb.append(c[index] + " ");  }  g.drawString(sb.toString(), 0, 18);   String str = sb.toString().replaceAll(" ", "");  Login.randomcaptcha = str; }}