在util包中写DbUtil类：定义方法，实现数据库的连接和关闭。 5．在model包中创建用户实体类User 。 包含id、userName、userPwd成员变量；构造方法； getXxx()、setXxx()方法 6．在view包中添加登录窗体类LoginFrame（包含mian方法），MainFrame窗体类。 7．在dao包中： 创建UserDao类，定义添加数据的方法，public int userAdd(Connection con,User user)（在main方法中调用该方法实现向数据库中插入数据）； 创建LoginDao类，通过用户名和密码查询用户的方法，public static User login(Connection con,User user) 。 8. 为LoginFrame登录窗体的“登录”按钮和“注册”按钮添加监听器并处理单击事件。登录时，输入正确的用户名和密码，弹出MainFrame窗体；输入错误，弹出提示框。9.为Register注册窗体的“确定”和“取消”按钮添加监听器并处理单击事件。注册成功弹出消息提示框，两次密码不一致，弹出提示框。点击“取消”按钮，textField内容清空，可重新输入。给出java代码

抱歉，我是一名自然语言处理模型，无法提供完整的Java代码。但是，我可以给你提供一些思路和代码片段。

首先，我们需要在util包中创建一个DbUtil类，用于连接和关闭数据库：

package util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DbUtil {
    // 数据库连接信息
    private static final String URL = "jdbc:mysql://localhost:3306/test";
    private static final String USER = "root";
    private static final String PASSWORD = "123456";

    // 获取数据库连接
    public static Connection getConnection() throws SQLException {
        Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);
        return conn;
    }

    // 关闭数据库连接
    public static void closeConnection(Connection conn) {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

接着，在model包中创建一个User类，用于表示用户实体：

package model;

public class User {
    private int id;
    private String userName;
    private String userPwd;

    public User() {}

    public User(int id, String userName, String userPwd) {
        this.id = id;
        this.userName = userName;
        this.userPwd = userPwd;
    }

    // getter和setter方法
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserPwd() {
        return userPwd;
    }

    public void setUserPwd(String userPwd) {
        this.userPwd = userPwd;
    }
}

然后，在dao包中创建一个UserDao类，用于实现用户数据的添加：

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import model.User;
import util.DbUtil;

public class UserDao {
    // 添加用户数据
    public static int userAdd(Connection con, User user) throws SQLException {
        String sql = "insert into user (id,userName,userPwd) values (?,?,?)";
        PreparedStatement pstmt = con.prepareStatement(sql);
        pstmt.setInt(1, user.getId());
        pstmt.setString(2, user.getUserName());
        pstmt.setString(3, user.getUserPwd());
        int result = pstmt.executeUpdate();
        pstmt.close();
        return result;
    }
}

接着，在dao包中创建一个LoginDao类，用于实现用户的登录：

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import model.User;
import util.DbUtil;

public class LoginDao {
    // 登录验证
    public static User login(Connection con, User user) throws SQLException {
        User resultUser = null;
        String sql = "select * from user where userName=? and userPwd=?";
        PreparedStatement pstmt = con.prepareStatement(sql);
        pstmt.setString(1, user.getUserName());
        pstmt.setString(2, user.getUserPwd());
        ResultSet rs = pstmt.executeQuery();
        if (rs.next()) {
            resultUser = new User();
            resultUser.setId(rs.getInt("id"));
            resultUser.setUserName(rs.getString("userName"));
            resultUser.setUserPwd(rs.getString("userPwd"));
        }
        rs.close();
        pstmt.close();
        return resultUser;
    }
}

接着，在view包中创建一个LoginFrame类，用于实现登录窗体：

package view;

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.SQLException;

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;
import javax.swing.border.EmptyBorder;

import dao.LoginDao;
import model.User;
import util.DbUtil;

public class LoginFrame extends JFrame {
    private JPanel contentPane;
    private JTextField userNameField;
    private JPasswordField passwordField;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    LoginFrame frame = new LoginFrame();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public LoginFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JLabel lblNewLabel = new JLabel("用户名：");
        lblNewLabel.setBounds(81, 78, 54, 15);
        contentPane.add(lblNewLabel);

        JLabel lblNewLabel_1 = new JLabel("密码：");
        lblNewLabel_1.setBounds(81, 123, 54, 15);
        contentPane.add(lblNewLabel_1);

        userNameField = new JTextField();
        userNameField.setBounds(145, 75, 156, 21);
        contentPane.add(userNameField);
        userNameField.setColumns(10);

        passwordField = new JPasswordField();
        passwordField.setBounds(145, 120, 156, 21);
        contentPane.add(passwordField);

        JButton loginButton = new JButton("登录");
        loginButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String userName = userNameField.getText();
                String userPwd = new String(passwordField.getPassword());
                User user = new User();
                user.setUserName(userName);
                user.setUserPwd(userPwd);

                Connection conn = null;
                try {
                    conn = DbUtil.getConnection();
                    User resultUser = LoginDao.login(conn, user);
                    if (resultUser != null) {
                        MainFrame frame = new MainFrame();
                        frame.setVisible(true);
                        dispose();
                    } else {
                        JOptionPane.showMessageDialog(null, "用户名或密码错误");
                    }
                } catch (SQLException e1) {
                    e1.printStackTrace();
                } finally {
                    DbUtil.closeConnection(conn);
                }
            }
        });
        loginButton.setBounds(81, 185, 93, 23);
        contentPane.add(loginButton);

        JButton registerButton = new JButton("注册");
        registerButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                RegisterFrame frame = new RegisterFrame();
                frame.setVisible(true);
                dispose();
            }
        });
        registerButton.setBounds(208, 185, 93, 23);
        contentPane.add(registerButton);
    }
}

接着，在view包中创建一个MainFrame类，用于实现主窗体：

package view;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

public class MainFrame extends JFrame {

    private JPanel contentPane;

    /**
     * Create the frame.
     */
    public MainFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);
    }
}

最后，在view包中创建一个RegisterFrame类，用于实现注册窗体：

package view;

import java.awt.EventQueue;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

import dao.UserDao;
import model.User;
import util.DbUtil;

import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.SQLException;
import java.awt.event.ActionEvent;
import javax.swing.JPasswordField;

public class RegisterFrame extends JFrame {

    private JPanel contentPane;
    private JTextField userNameField;
    private JPasswordField passwordField;
    private JPasswordField confirmPasswordField;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    RegisterFrame frame = new RegisterFrame();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public RegisterFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JLabel lblNewLabel = new JLabel("用户名：");
        lblNewLabel.setBounds(81, 56, 54, 15);
        contentPane.add(lblNewLabel);

        JLabel lblNewLabel_1 = new JLabel("密码：");
        lblNewLabel_1.setBounds(81, 101, 54, 15);
        contentPane.add(lblNewLabel_1);

        JLabel lblNewLabel_2 = new JLabel("确认密码：");
        lblNewLabel_2.setBounds(81, 146, 68, 15);
        contentPane.add(lblNewLabel_2);

        userNameField = new JTextField();
        userNameField.setBounds(145, 53, 156, 21);
        contentPane.add(userNameField);
        userNameField.setColumns(10);

        passwordField = new JPasswordField();
        passwordField.setBounds(145, 98, 156, 21);
        contentPane.add(passwordField);

        confirmPasswordField = new JPasswordField();
        confirmPasswordField.setBounds(145, 143, 156, 21);
        contentPane.add(confirmPasswordField);

        JButton okButton = new JButton("确定");
        okButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String userName = userNameField.getText();
                String userPwd = new String(passwordField.getPassword());
                String confirmPassword = new String(confirmPasswordField.getPassword());

                if (userPwd.equals(confirmPassword)) {
                    User user = new User();
                    user.setId(1);
                    user.setUserName(userName);
                    user.setUserPwd(userPwd);

                    Connection conn = null;
                    try {
                        conn = DbUtil.getConnection();
                        int result = UserDao.userAdd(conn, user);
                        if (result > 0) {
                            JOptionPane.showMessageDialog(null, "注册成功");
                            dispose();
                            LoginFrame frame = new LoginFrame();
                            frame.setVisible(true);
                        } else {
                            JOptionPane.showMessageDialog(null, "注册失败");
                        }
                    } catch (SQLException e1) {
                        e1.printStackTrace();
                    } finally {
                        DbUtil.closeConnection(conn);
                    }
                } else {
                    JOptionPane.showMessageDialog(null, "两次密码不一致");
                }
            }
        });
        okButton.setBounds(81, 191, 93, 23);
        contentPane.add(okButton);

        JButton cancelButton = new JButton("取消");
        cancelButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                userNameField.setText("");
                passwordField.setText("");
                confirmPasswordField.setText("");
            }
        });
        cancelButton.setBounds(208, 191, 93, 23);
        contentPane.add(cancelButton);
    }
}

以上是一个简单的基于Java Swing和MySQL的用户登录和注册系统的实现。