Java登陆界面怎么写

Java登录界面的实现可以分为以下几个步骤：

1. 创建登录窗口

JFrame loginFrame = new JFrame("登录窗口");
loginFrame.setSize(300, 200);
loginFrame.setLocationRelativeTo(null);
loginFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

2. 添加用户名、密码输入框和登录按钮

JPanel loginPanel = new JPanel(new GridLayout(3, 2));
JLabel usernameLabel = new JLabel("用户名：");
JTextField usernameField = new JTextField();
JLabel passwordLabel = new JLabel("密  码：");
JPasswordField passwordField = new JPasswordField();
JButton loginButton = new JButton("登录");
loginPanel.add(usernameLabel);
loginPanel.add(usernameField);
loginPanel.add(passwordLabel);
loginPanel.add(passwordField);
loginPanel.add(new JLabel());
loginPanel.add(loginButton);
loginFrame.add(loginPanel);

3. 添加登录按钮的监听器，验证用户名和密码

loginButton.addActionListener(e -> {
    String username = usernameField.getText().trim();
    String password = new String(passwordField.getPassword());
    if ("admin".equals(username) && "123456".equals(password)) {
        JOptionPane.showMessageDialog(loginFrame, "登录成功！");
    } else {
        JOptionPane.showMessageDialog(loginFrame, "用户名或密码错误！");
    }
});

完整的代码示例：

import javax.swing.*;

public class LoginFrame {

    public static void main(String[] args) {
        JFrame loginFrame = new JFrame("登录窗口");
        loginFrame.setSize(300, 200);
        loginFrame.setLocationRelativeTo(null);
        loginFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel loginPanel = new JPanel(new GridLayout(3, 2));
        JLabel usernameLabel = new JLabel("用户名：");
        JTextField usernameField = new JTextField();
        JLabel passwordLabel = new JLabel("密  码：");
        JPasswordField passwordField = new JPasswordField();
        JButton loginButton = new JButton("登录");
        loginPanel.add(usernameLabel);
        loginPanel.add(usernameField);
        loginPanel.add(passwordLabel);
        loginPanel.add(passwordField);
        loginPanel.add(new JLabel());
        loginPanel.add(loginButton);
        loginFrame.add(loginPanel);

        loginButton.addActionListener(e -> {
            String username = usernameField.getText().trim();
            String password = new String(passwordField.getPassword());
            if ("admin".equals(username) && "123456".equals(password)) {
                JOptionPane.showMessageDialog(loginFrame, "登录成功！");
            } else {
                JOptionPane.showMessageDialog(loginFrame, "用户名或密码错误！");
            }
        });

        loginFrame.setVisible(true);
    }
}