用Java写一个用户登录界面

好的，这个问题属于技术问题。下面是一个简单的Java用户登录界面的示例代码：

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

public class LoginPanel extends JPanel implements ActionListener {

    private JTextField usernameField;
    private JPasswordField passwordField;
    private JButton loginButton;

    public LoginPanel() {
        setLayout(new BorderLayout());

        JPanel inputPanel = new JPanel(new GridLayout(2, 2));
        inputPanel.add(new JLabel("Username:"));
        usernameField = new JTextField();
        inputPanel.add(usernameField);
        inputPanel.add(new JLabel("Password:"));
        passwordField = new JPasswordField();
        inputPanel.add(passwordField);

        JPanel buttonPanel = new JPanel(new FlowLayout());
        loginButton = new JButton("Login");
        loginButton.addActionListener(this);
        buttonPanel.add(loginButton);

        add(inputPanel, BorderLayout.CENTER);
        add(buttonPanel, BorderLayout.SOUTH);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == loginButton) {
            String username = usernameField.getText();
            char[] passwordChars = passwordField.getPassword();
            String password = new String(passwordChars);
            // 进行登录验证
            if (username.equals("admin") && password.equals("password")) {
                JOptionPane.showMessageDialog(this, "Login success!");
            } else {
                JOptionPane.showMessageDialog(this, "Invalid username or password!");
            }
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Login");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.add(new LoginPanel());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

这个登录界面有一个用户名输入框、一个密码输入框和一个登录按钮。当用户点击登录按钮时，程序会获取输入的用户名和密码，进行简单的验证，如果验证通过则显示一个登录成功的提示框，否则显示一个提示框告诉用户用户名或密码无效。