有三个类：Test.java、Customer.java、CustomerDAO.java、ATMSystem.java

ATMSystem.java实现模拟ATM的功能

Customer.java创建一个用户对象

CustomerDAO.java实现连接数据库

Test为主程序

 

 

ATMSystem.java:

package ATM;

import java.util.Scanner;

public class ATMSystem 
{
	CustomerDAO dao=new CustomerDAO();
	Scanner input=new Scanner(System.in);
	private int id;
	public ATMSystem()
	{
		
	}
	public void Regist()
	{
		System.out.println("注册卡号：");
		int myid=input.nextInt();
		System.out.println("注册用户名：");
		String myname=input.next();
		System.out.println("注册密码：");
		int mypwd=input.nextInt();
		System.out.println("输入存入金额：");
		int mymoney=input.nextInt();
		dao.Regist(myid, mypwd, myname, mymoney);
	}
	public boolean login()
	{
		System.out.println("请输入密码：");
		int mypwd=input.nextInt();
		id=dao.login(mypwd);
		if(id==-1)
		{
			System.out.println("登录失败！");
			return false;
		}
		else
		{
			System.out.println("登陆成功！");
			return true;
		}
	}
	public void query(int id)
	{
		Customer cust=dao.query(id);
		System.out.println("********************");
		System.out.println("卡号："+cust.getid());
		System.out.println("余额："+cust.getmoney());
		System.out.println("用户名："+cust.getname());
		System.out.println("********************");
	}
	public void save()
	{
		System.out.println("输入存款金额：");
		int money=input.nextInt();
		dao.update_save(id, money);
	}
	public void get()
	{
		System.out.println("********************");
		System.out.println("输入取款金额：");
		int money=input.nextInt();
		dao.update_get(id, money);
		System.out.println("********************");
	}
	public void change()
	{
		System.out.println("请输入转账卡号：");
		int inid=input.nextInt();
		System.out.println("请输入转账金额：");
		int money=input.nextInt();
		dao.change(id, inid, money);
	}
	public void begin()
	{
		int num=-1;
		int Num=-1;
		System.out.println("请选择功能：");
		System.out.println("1.注册           2.登录 	3.退出");
		Num=input.nextInt();
		switch(Num)
		{
		case 1:
			Regist();
			break;
		case 2:
			if(login())
			{
				while(num!=0)
				{
					System.out.println("********************");
					System.out.println("欢迎欢迎，热烈欢迎");
					System.out.println("请选择功能：");
					System.out.println("1.存款         2.取款      3.查询      4.转账    0.退出");
					System.out.println("********************");
					num=input.nextInt();
					switch(num)
					{
					case 1:
						save();
						break;
					case 2:
						get();
						break;
					case 3:
						query(id);
						break;
					case 4:
						change();
						break;
					case 0:
						System.out.println("谢谢使用！");
						break;
					}
				}
			}
			else
			{
				System.out.println("登录失败，账号、密码错误！");
			}
		break;
		}
	}
}

Customer.java

package ATM;

public class Customer 
{
	private int id;
	private int pwd;
	private int money;
	private String name;
	public int getid()
	{
		return id;
	}
	public void setid(int newid)
	{
		id=newid;
	}
	public int getpwd()
	{
		return pwd;
	}
	public void setpwd(int newpwd)
	{
		pwd=newpwd;
	}
	public String getname()
	{
		return name;
	}
	public void setname(String newname)
	{
		name=newname;
	}
	public int getmoney()
	{
		return money;
	}
	public void setmoney(int newmoney)
	{
		money=newmoney;
	}
}

CustomerDAO.java:

package ATM;

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


public class CustomerDAO
{
	private Connection conn=null;
	private java.sql.PreparedStatement p=null;
	public CustomerDAO()
	{
		try {
			Class.forName("org.gjt.mm.mysql.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		try {
			conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql", "root", "");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public int login(int mypwd)
	{
		String sql="select * from mysql where pwd = ?";
		try 
		{
			p=conn.prepareStatement(sql);
			p.setInt(1, mypwd);
			ResultSet rs=p.executeQuery();
			if(rs.next())
			{
				return rs.getInt("id");
			}
			rs.close();
			p.close();
			conn.close();
		} 
		catch (SQLException e) 
		{
			e.printStackTrace();
		}
		return -1;
	}
	public Customer query(int id)
	{
		Customer cust=new Customer();
		try
		{
			String sql="select * from mysql where id = ?";
			p=conn.prepareStatement(sql);
			p.setInt(1, id);
			ResultSet rs=p.executeQuery();
			if(rs.next())
			{
				cust.setid(rs.getInt("id"));
				cust.setmoney(rs.getInt("money"));
				cust.setname(rs.getString("name"));
				cust.setpwd(rs.getInt("pwd"));
			}
			rs.close();
			p.close();
			conn.close();
		}
		catch (Exception e) {
			// TODO: handle exception
		}
		return cust;

	}
	public void update_get(int id,int money) 
	{
		String sql="select * from mysql where id = ?";
		try 
		{
			p=conn.prepareStatement(sql);
			p.setInt(1, id);
			ResultSet rs=p.executeQuery();
			if(rs.next())
			{
				if(rs.getInt("money")<money)
				{
					System.out.println("余额不足！");
				}
				else
				{
					sql="update mysql set money = money - ? where id = ?";
					p=conn.prepareStatement(sql);
					p.setInt(1, money);
					p.setInt(2, id);
					p.executeUpdate();
					System.out.println("取款成功！");
				}
			}
			rs.close();
			p.close();
			conn.close();
		}
		catch (Exception e)
		{
			// TODO: handle exception
		}
	}
	public void update_save(int id,int money)
	{
		String sql="update mysql set money = money + ? where id = ?";
		try 
		{
			p=conn.prepareStatement(sql);
			p.setInt(1, money);
			p.setInt(2, id);
			p.executeUpdate();
			System.out.println("存款成功！");
			p.close();
			conn.close();
		}
		catch (Exception e) 
		{
			// TODO: handle exception
		}
	}
	public void change(int myid,int inid,int money)
	{
		try
		{	String sql="select * from mysql where id = ?";
			p=conn.prepareStatement(sql);
			p.setInt(1, inid);
			ResultSet rs=p.executeQuery();
			if(rs.next())
			{
				sql="select * from mysql where id = ?";
				p=conn.prepareStatement(sql);
				p.setInt(1, myid);
				rs=p.executeQuery();
				if(rs.next())
				{
					if(rs.getInt("money")<money)
					{
						System.out.println("余额不足！");
						return;
					}
					else
					{
						sql="update mysql set money = money - ? where id = ?";
						p=conn.prepareStatement(sql);
						p.setInt(1, money);
						p.setInt(2, myid);
						p.executeUpdate();
						sql="update mysql set money = money + ? where id = ?";
						p=conn.prepareStatement(sql);
						p.setInt(1, money);
						p.setInt(2, inid);
						p.executeUpdate();
					}
				}
			}
			else
			{
				System.out.println("卡号错误！");
			}
			rs.close();
			p.close();
			conn.close();
		}
		catch (Exception e) {
			// TODO: handle exception
		}
	}
	public void Regist(int myid,int mypwd,String myname,int mymoney)
	{
		String sql;
		try
		{
			sql="select * from mysql where id = ?";
			p=conn.prepareStatement(sql);
			p.setInt(1, myid);
			ResultSet rs=p.executeQuery();
			if(rs.next())
			{
				System.out.println("此卡已注册，请勿重复注册！！！！");
				rs.close();
				p.close();
				conn.close();
				return;
			}
		}
		catch (Exception e)
		{
			// TODO: handle exception
		}
		
		try 
		{
			sql="insert into mysql(id,pwd,money,name) values(?,?,?,?)";
			p=conn.prepareStatement(sql);
			p.setInt(1, myid);
			p.setInt(2, mypwd);
			p.setInt(3, mymoney);
			p.setString(4, myname);
			p.executeUpdate();
			System.out.println("注册成功！");
			p.close();
			conn.close();
		}
		catch (Exception e) 
		{
			// TODO: handle exception
		}
	}
}

Test.java:

package ATM;

public class Test 
{
	public static void main(String[] args) 
	{
		// TODO Auto-generated method stub
		ATMSystem ATM=new ATMSystem();
		while(true)
		{
			ATM.begin();
		}
	}

}