用java写一个登录页面

好的，以下是一个简单的登录页面的Java代码示例：

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

public class LoginPage extends JFrame implements ActionListener {
    private JTextField usernameField;
    private JPasswordField passwordField;
    private JButton loginButton;
    private JLabel statusLabel;

    public LoginPage() {
        setTitle("Login Page");
        setSize(400, 200);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.fill = GridBagConstraints.HORIZONTAL;

        JLabel usernameLabel = new JLabel("Username:");
        constraints.gridx = 0;
        constraints.gridy = 0;
        constraints.gridwidth = 1;
        panel.add(usernameLabel, constraints);

        usernameField = new JTextField(20);
        constraints.gridx = 1;
        constraints.gridy = 0;
        constraints.gridwidth = 2;
        panel.add(usernameField, constraints);

        JLabel passwordLabel = new JLabel("Password:");
        constraints.gridx = 0;
        constraints.gridy = 1;
        constraints.gridwidth = 1;
        panel.add(passwordLabel, constraints);

        passwordField = new JPasswordField(20);
        constraints.gridx = 1;
        constraints.gridy = 1;
        constraints.gridwidth = 2;
        panel.add(passwordField, constraints);

        loginButton = new JButton("Login");
        constraints.gridx = 1;
        constraints.gridy = 2;
        constraints.gridwidth = 1;
        panel.add(loginButton, constraints);

        statusLabel = new JLabel("", JLabel.CENTER);
        constraints.gridx = 0;
        constraints.gridy = 3;
        constraints.gridwidth = 3;
        panel.add(statusLabel, constraints);

        add(panel);

        loginButton.addActionListener(this);
        setVisible(true);
    }

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

        if (username.equals("admin") && password.equals("password")) {
            statusLabel.setText("Login successful!");
        } else {
            statusLabel.setText("Invalid username or password!");
        }
    }

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

这个登录页面包含了一个用户名输入框、一个密码输入框和一个登录按钮。当用户点击登录按钮时，程序会读取输入框中的用户名和密码，然后进行验证。如果用户名和密码都正确，程序会显示“Login successful!”的提示，否则会显示“Invalid username or password!”的提示。