Java 登陆界面示例代码：简单易懂

以下是一个简单的 Java 登陆界面的示例代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class LoginFrame extends JFrame implements ActionListener {
    private JTextField usernameField;
    private JPasswordField passwordField;
    private JButton loginButton;
    private JButton cancelButton;

    public LoginFrame() {
        this.setTitle('Login');
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setSize(300, 150);
        this.setResizable(false);

        JPanel panel = new JPanel(new GridLayout(3, 2));

        JLabel usernameLabel = new JLabel('Username:');
        panel.add(usernameLabel);

        usernameField = new JTextField();
        panel.add(usernameField);

        JLabel passwordLabel = new JLabel('Password:');
        panel.add(passwordLabel);

        passwordField = new JPasswordField();
        panel.add(passwordField);

        loginButton = new JButton('Login');
        loginButton.addActionListener(this);
        panel.add(loginButton);

        cancelButton = new JButton('Cancel');
        cancelButton.addActionListener(this);
        panel.add(cancelButton);

        this.add(panel);
        this.setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == loginButton) {
            String username = usernameField.getText();
            String password = new String(passwordField.getPassword());

            if (username.equals('admin') && password.equals('password')) {
                JOptionPane.showMessageDialog(this, 'Login successful!');
            } else {
                JOptionPane.showMessageDialog(this, 'Invalid username or password!');
            }
        } else if (e.getSource() == cancelButton) {
            System.exit(0);
        }
    }

    public static void main(String[] args) {
        new LoginFrame();
    }
}

该代码创建了一个包含用户名、密码、登录和取消按钮的简单登陆界面。当用户单击'登录'按钮时，代码将检查用户名和密码是否正确，并在弹出窗口中显示相应的消息。如果用户单击'取消'按钮，则应用程序将退出。