这个是我们学校的实训的作业，本人有些不太理解， 求高手帮忙看一下，小弟不胜感激

[ManaStuDent]

/*这个是我们学校的实训的作业，本人有些不太理解， 求高手帮忙看一下，小弟不胜感激。
这个项目是一个ATM取款机的窗口，用的是JDBC和MySpl；
我创建了4个包  bean,dao,frame,util
功能要求是（1）账户登录，这个已经解决（2）取款，存款，查询余额，和修改密码。
取款有问题，望高手解决。
查询余额和修改密码，本人不是很理解，请大家补充完整。
修改密码要在新的界面下修改。

以下是代码：*/
package com.wxcsxy.bean;
public class Account {
	private int id;
	private String userName;
	private String userPwd;
	private String accountNumber;
	private double balance;
	private String type;
//这里省略构造函数和Getter Setter方法	

}

package com.wxcsxy.dao;
public class AccountDAO {
	public Account validateLogin(String userName,String userPwd)
	{
		Account account = null;
		//获得数据库的连接
		Connection con = DBConnection.getConnection();
		//定义SQL语句
		String sql = "select * from account where userName=? and userPwd 

=?";
		//定义语句对象
		PreparedStatement stmt = null;
		//定义结果集对象
		ResultSet rs = null;
		try {
			stmt = con.prepareStatement(sql);
			//为语句对象的参数进行赋值
			stmt.setString(1, userName);
			stmt.setString(2, userPwd);
			//执行语句对象
			rs = stmt.executeQuery();
			//如果account不为空，将结果集中的数据封装到account中
			if(rs.next())
			{
				account = new Account();
				account.setId(rs.getInt(1));
				account.setUserName(rs.getString(2));
				account.setUserPwd(rs.getString(3));
				account.setAccountNumber(rs.getString(4));
				account.setBalance(rs.getDouble(5));
				account.setType(rs.getString(6));
			}
			
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return account;
	}
	
	//存款操作
	public boolean desposit(Account account,double amt)
	{
		//定义状态变量result
		boolean result = true;
		int n = 0;
		//获取当前帐户原有的余额
		double balance = account.getBalance();
		//获得数据库的连接
		Connection con = DBConnection.getConnection();
		//定义SQL语句
		String sql = "update account set balance = ? where id=?";
		//定义语句对象
		PreparedStatement stmt = null;
		try {
			stmt = con.prepareStatement(sql);
			stmt.setDouble(1, balance+amt);
			stmt.setInt(2, account.getId());
			
			n = stmt.executeUpdate();
			if(n==0)
				result  = false;
			else
			{
				account.setBalance(balance+amt);
			}
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return result;
	}
	//取款操作
	public boolean withDraw(Account account,double amt)
	{
		boolean result = true;
		int n = 0;
		//获取当前帐户原有的余额
		double balance = account.getBalance();
		//获得数据库的连接
		Connection con = DBConnection.getConnection();
		//定义SQL语句
		String sql = "update account set balance = ? where id=?";
		//定义语句对象
		PreparedStatement stmt = null;
		try {
			stmt = con.prepareStatement(sql);
			stmt.setDouble(1, balance-amt);
			stmt.setInt(2, account.getId());
			
			n = stmt.executeUpdate();
			if(n==0){
				result  = false;
			}
			else 		
				account.setBalance(balance-amt);		
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return result;
	}
//查询 怎么做？？
//修改密码
	public boolean updatePwd(Account account,String oldPwd,String newPwd)
	{
		boolean result = true;
		
		return result;
	}
	
}

package com.wxcsxy.frame;
public class LoginFrame extends JFrame {
	private JLabel lblTitle;
	private JTextField txtUserName;
	private JPasswordField txtUserPwd;
	private JButton btnLogin,btnExit;
	//定义静态变量保存登录用户信息
	private static Account account;	
	public static Account getAccount() {
		return account;
	}
	public static void setAccount(Account account) {
		LoginFrame.account = account;
	}
	public LoginFrame()
	{
		this.setTitle("ATM系统登录窗口");
		this.setResizable(false);
		this.setLayout(null);
		Toolkit kit = Toolkit.getDefaultToolkit();
		Dimension screenSize = kit.getScreenSize();
		int screenWidth = screenSize.width;
		int screenHeight = screenSize.height;
		this.setBounds(screenWidth/2-100, screenHeight/2-100,300 , 300);
		
		lblTitle = new JLabel("用户名：");
		lblTitle.setBounds(30, 100, 60, 25);
		this.add(lblTitle);
		
		txtUserName = new JTextField(20);
		txtUserName.setBounds(100, 100, 160, 25);
		this.add(txtUserName);
		
		lblTitle = new JLabel("密     码：");
		lblTitle.setBounds(30, 140, 60, 25);
		this.add(lblTitle);
		
		txtUserPwd = new JPasswordField(20);
		txtUserPwd.setBounds(100, 140, 160, 25);
		txtUserPwd.addKeyListener(new KeyAdapter() {
			public void keyPressed(final KeyEvent e) {
				if (e.getKeyCode() == KeyEvent.VK_ENTER)
					btnLogin.doClick();
			}
		});

		this.add(txtUserPwd);
		
		btnLogin = new JButton("登录");
		btnLogin.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent e) {
				//获取界面中用户名和密码
				String userName = txtUserName.getText().trim();
				String userPwd = new String(txtUserPwd.getPassword

());
				//验证用户是否合法
				AccountDAO accountDAO = new AccountDAO();
				account = accountDAO.validateLogin(userName, 

userPwd);
				//判断下一步的操作:如果account不为空，进入下一个界

面；否则，给出错误的提示
				if(account!=null)
				{
					LoginFrame.this.setVisible(false);
					new MainFrame();
				}
				else
				{
					JOptionPane.showMessageDialog(null, "该用户

名不存在或者密码有误！");
				}
			}
		});
		btnLogin.setBounds(60, 200, 70, 25);
		this.add(btnLogin);
		btnExit = new JButton("退出");
		btnExit.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent e) {
				// TODO Auto-generated method stub
				System.exit(0);
			}
		});
		btnExit.setBounds(180, 200, 70, 25);
		this.add(btnExit);
		
		
		
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);
	}
	public static void main(String[] args) {
		new LoginFrame();
	}
}





package com.wxcsxy.frame;
public class MainFrame extends JFrame {
	private JButton btnWithDraw,btnDeposit,btnQuery,btnExit,btnUpdatePwd;
	public MainFrame()
	{
		this.setTitle("ATM系统主界面");
		this.setResizable(false);
		this.setLayout(null);
		Toolkit kit = Toolkit.getDefaultToolkit();
		Dimension screenSize = kit.getScreenSize();
		int screenWidth = screenSize.width;
		int screenHeight = screenSize.height;
		this.setBounds(screenWidth/4, screenHeight/4, screenWidth/2-200, 

screenHeight/2);
		
		btnWithDraw = new JButton("取款");
		btnWithDraw.setBounds(200, 50, 70, 25);
		
		btnWithDraw.addActionListener(new ActionListener()
		{
            @Override
			public void actionPerformed(ActionEvent e) {
				String inputMoney = JOptionPane.showInputDialog("请

输入取款的数额：");
				AccountDAO accountDAO = new AccountDAO();
				double amt = Double.parseDouble(inputMoney);
				if(amt>0)
				{
					boolean result = accountDAO.withDraw

(LoginFrame.getAccount(), amt);
					if(result)
					{
			
						JOptionPane.showMessageDialog(null, 

"您的取款数额是："+amt+",取款成功！");
					}
					else
					{
						JOptionPane.showMessageDialog(null, 

"存款失败，请重新操作！");
					}
				}
				else
				{
					JOptionPane.showMessageDialog(null, "您输入

的存款数额格式错误，请重新再输！");
				}
				
			}
			
		}
		);
		this.add(btnWithDraw);
		
		btnDeposit = new JButton("存款");
		btnDeposit.setBounds(200, 100, 70, 25);
		btnDeposit.addActionListener(new ActionListener()
		{
			@Override
			public void actionPerformed(ActionEvent e) {
				// 告知存款的数额
				//完成存款的业务逻辑，修改数据库
				//告知用户存款的结果
				String inputMoney = JOptionPane.showInputDialog("请

输入存款的数额：");
				AccountDAO accountDAO = new AccountDAO();
				double amt = Double.parseDouble(inputMoney);
				if(amt>0)
				{
					boolean result = accountDAO.desposit

(LoginFrame.getAccount(), amt);
					if(result)
					{
						JOptionPane.showMessageDialog(null, 

"您的存款数额是："+amt+",存款成功！");
					}
					else
					{
						JOptionPane.showMessageDialog(null, 

"存款失败，请重新操作！");
					}
				}
				else
				{
					JOptionPane.showMessageDialog(null, "您输入

的存款数额格式错误，请重新再输！");
				}
				
			}
			
		}
		);
		this.add(btnDeposit);
		
		btnQuery = new JButton("查询");
		btnQuery.addActionListener(new ActionListener()
		{
			@Override
			public void actionPerformed(ActionEvent e) 
			}		
		}
		);
		btnQuery.setBounds(200, 150, 70, 25);
		this.add(btnQuery);
		
		btnUpdatePwd = new JButton("修改密码");
		btnUpdatePwd.setBounds(200, 200, 70, 25);
		this.add(btnUpdatePwd);
		
		btnExit = new JButton("退出");
		btnExit.setBounds(200, 250, 70, 25);
		this.add(btnExit);
		
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);
		
	}
	
	public static void main(String[] args) {
		new MainFrame();
	}	
}

package com.wxcsxy.frame;
public class upDatePwdFrame extends JFrame {
	private JPanel panel;
	private JLabel lalUserOldPwd,lalUserNewPwd1,lalUserNewPwd2;
	private JPasswordField userPwd1,userPwd2,userPwd3;
	private JButton btnAffirm,btnReset;	
	public upDatePwdFrame(){
		this.setTitle("修改密码");
		this.setBounds(100, 100, 300, 200);
		this.setLayout(new GridLayout(4,1));
		
		panel = new JPanel();
		lalUserOldPwd = new JLabel("原始密码");
		userPwd1 = new JPasswordField(12);
		panel.add(lalUserOldPwd);
		panel.add(userPwd1);
		this.add(panel);
		
		panel = new JPanel();
		lalUserNewPwd1 = new JLabel("新始密码");
		userPwd2 = new JPasswordField(12);
		panel.add(lalUserNewPwd1);
		panel.add(userPwd2);
		this.add(panel);
		
		panel = new JPanel();
		lalUserNewPwd2 = new JLabel("确认密码");
		userPwd3 = new JPasswordField(12);
		panel.add(lalUserNewPwd2);
		panel.add(userPwd3);
		this.add(panel);
		
		panel = new JPanel();
		btnAffirm = new JButton("确认");
		btnReset = new JButton("重置");
		panel.add(btnAffirm);
		panel.add(btnReset);
		this.add(panel);
	
		this.setVisible(true);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);		
	}
	public static void main(String[] args) {
		new upDatePwdFrame();
	}
}

package com.wxcsxy.util;
public class DBConnection {
	private static Connection con = null;
	
	public static Connection getConnection()
	{
		try {
			Class.forName("com.mysql.jdbc.Driver");
			con = DriverManager.getConnection

("jdbc:mysql://localhost:3306/atmdb", "root", "wxcsxy");
			System.out.println("数据库联接成功");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return con;
	}
}

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