程序员，请创建一个Java游戏项目名叫www,包名叫www,并在包内创建一个login类，login类实现一个带有登录注册并连接数据库的游戏窗口，以代码形式并附上中文注释，然后建个main类来实现主页面，主页面有三个按钮，分别是‘开始游戏’，‘选择英雄机’，‘设置’，登陆成功后就跳转到主页面。请以代码形式呈现

好的，以下是Java代码：

首先创建Java项目`www`，并在包`www`中创建`Login`类：

package www;

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Login extends JFrame implements ActionListener {

    private JTextField tfUserName;
    private JPasswordField tfPassword;
    private JButton btnLogin, btnRegister;

    private static final String DB_URL = "jdbc:mysql://localhost:3306/game";
    private static final String USER = "root";
    private static final String PASS = "password";

    public Login() {
        initUI();
    }

    private void initUI() {
        setTitle("游戏登录");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel(new BorderLayout());
        JPanel panelNorth = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel panelCenter = new JPanel(new FlowLayout(FlowLayout.CENTER));
        JPanel panelSouth = new JPanel(new FlowLayout(FlowLayout.CENTER));

        JLabel lblUserName = new JLabel("用户名:");
        tfUserName = new JTextField(20);

        JLabel lblPassword = new JLabel("密码:");
        tfPassword = new JPasswordField(20);

        btnLogin = new JButton("登录");
        btnLogin.addActionListener(this);

        btnRegister = new JButton("注册");
        btnRegister.addActionListener(this);

        panelNorth.add(lblUserName);
        panelNorth.add(tfUserName);
        panelNorth.add(lblPassword);
        panelNorth.add(tfPassword);
        panelCenter.add(btnLogin);
        panelCenter.add(btnRegister);

        panel.add(panelNorth, BorderLayout.NORTH);
        panel.add(panelCenter, BorderLayout.CENTER);
        panel.add(panelSouth, BorderLayout.SOUTH);

        setContentPane(panel);
        pack();
        setLocationRelativeTo(null);
    }

    private boolean isValidUser(String userName, String password) {
        boolean isValid = false;
        try (Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
                Statement stmt = conn.createStatement();) {
            String sql = "SELECT * FROM user WHERE username='" + userName + "' AND password='" + password + "'";
            ResultSet rs = stmt.executeQuery(sql);
            if (rs.next()) {
                isValid = true;
            }
        } catch (SQLException ex) {
            System.err.println(ex);
        }
        return isValid;
    }

    private void registerUser(String userName, String password) {
        try (Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
                Statement stmt = conn.createStatement();) {
            String sql = "INSERT INTO user (username, password) VALUES ('" + userName + "', '" + password + "')";
            stmt.executeUpdate(sql);
        } catch (SQLException ex) {
            System.err.println(ex);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnLogin) {
            String userName = tfUserName.getText();
            String password = String.valueOf(tfPassword.getPassword());
            if (isValidUser(userName, password)) {
                JOptionPane.showMessageDialog(this, "登录成功！");
                openMainPage();
            } else {
                JOptionPane.showMessageDialog(this, "用户名或密码错误！");
            }
        } else if (e.getSource() == btnRegister) {
            String userName = tfUserName.getText();
            String password = String.valueOf(tfPassword.getPassword());
            registerUser(userName, password);
            JOptionPane.showMessageDialog(this, "注册成功！");
        }
    }

    private void openMainPage() {
        Main main = new Main();
        main.setVisible(true);
        dispose();
    }
}

在`Login`类中，我们实现了一个带有登录注册并连接数据库的游戏窗口。使用`JFrame`类来创建窗口界面，包括用户名输入框、密码输入框、登录按钮和注册按钮。通过`isValidUser`方法来验证用户是否合法，并通过`registerUser`方法来注册新用户。

接下来是`Main`类，用于实现主页面，包含三个按钮：开始游戏、选择英雄机和设置：

package www;

import java.awt.BorderLayout;
import java.awt.FlowLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JFrame {

    public Main() {
        initUI();
    }

    private void initUI() {
        setTitle("游戏主页面");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel(new BorderLayout());
        JPanel panelCenter = new JPanel(new FlowLayout(FlowLayout.CENTER));

        JButton btnStartGame = new JButton("开始游戏");
        JButton btnSelectHero = new JButton("选择英雄机");
        JButton btnSetting = new JButton("设置");

        panelCenter.add(btnStartGame);
        panelCenter.add(btnSelectHero);
        panelCenter.add(btnSetting);

        panel.add(panelCenter, BorderLayout.CENTER);

        setContentPane(panel);
        pack();
        setLocationRelativeTo(null);
    }
}

在`Main`类中，我们创建了一个`JFrame`窗口，并添加了三个按钮：开始游戏、选择英雄机和设置。最后，我们将`panelCenter`添加到`panel`中，并将其设置为窗口的内容面板。在`initUI`方法中，使用了`BorderLayout`和`FlowLayout`布局管理器来实现按钮的布局。

最后，在`Login`类中，在`isValidUser`方法中添加以下代码，以实现在登录成功后打开主页面：

private void openMainPage() {
    Main main = new Main();
    main.setVisible(true);
    dispose();
}

在登录成功后，通过`openMainPage`方法打开`Main`类，并关闭当前的登录窗口。