第一次学Java，写的比较拙劣

test类

package bank;

import java.util.Scanner;

public class test {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		System.out.println("0.退出\t1.管理员\t2.普通用户\n请选择你的身份:");
		int identity = sc.nextInt();
		
		MySQL mysql = new MySQL();
		SqlUser sqluser = new SqlUser();
		mysql.runOneTime();//载入全部信息只运行一次
		
		if (identity == 1) {
			mysql.SqlAdminLogin();
			mysql.SqlAdminQuery();
		} else if(identity == 2){
			sqluser.SqlUserLogin();
		}else if(identity == 0) {
			System.out.println("****感谢使用，期待下次合作！****");
			System.exit(0);	
		}else {
			System.out.println("出错误啦~");
		}
		sc.close();
	}
	
}

 SqlUser类

package bank;

import java.sql.*;
import java.util.*;

public class SqlUser {
	Connection conn = null;
	Statement stmt = null;
	ResultSet rs = null;
	Scanner sc = new Scanner(System.in);
	int CardID = 0;

	public void SqlUserLogin() throws SQLException {

		int psw;
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String username = "root";
			String password = "078772";
			conn = DriverManager.getConnection(url, username, password);
			stmt = conn.createStatement();

			System.out.print("请输入你的卡号:");
			CardID = sc.nextInt();
			System.out.print("请输入你的密码:");
			psw = sc.nextInt();

			String sqlSingle = "select * from BankDB where CardID = " + CardID + " AND Password =" + psw + "";

			rs = stmt.executeQuery(sqlSingle);
			String name = null;
			String sex = null;
			while (rs.next()) {

				name = rs.getString("Username");
				sex = rs.getString("Sex");
			}
			while (true) {
				if (name == null) {
					System.out.println("**您还没有办理服务或输入有错哦！**\n您要创建新用户吗？\n1.不，我再试试\t2.好\t3.直接退出");
					int choice = sc.nextInt();
					switch (choice) {
					case 1: {
						SqlUserLogin();
						break;
					}
					case 2: {
						inputWrite();
						break;
					}
					case 3: {
						System.out.println("***即将退出系统***");
						System.exit(0);
					}
					default: {
						System.out.println("***输入错误***");
					}
					}
				} else {
					System.out.println("Yuelin智能ATMer欢迎" + name + sex + "士！");
					System.out.print("1.存款\n2.取款\n3.查询\n4.修改密码\n0.退出\n请输入您的选择:");
					int userChoice = sc.nextInt();
					switch (userChoice) {
					case 1: {
						SqlUserSave();
						break;
					}
					case 2: {
						SqlUserWithdraw();
						break;
					}
					case 3: {
						SqlUserQuery();
						break;
					}
					case 4: {
						SqlUserChangePsw();
						break;
					}
					case 0: {

						System.exit(0);
					}
					}
				}
			}
		} catch (Exception e) {
			System.out.println("这里有一些错误哦~");
			e.printStackTrace();
		} finally {
			if (rs != null)
				rs.close();
			if (stmt != null)
				stmt.close();
			if (conn != null)
				conn.close();
		}
	}

	public void inputWrite() throws SQLException {

		String name = null, sex = null;
		int psw, id = 0;
		int count = 0, newcardId = 0;

		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String username = "root";
			String password = "078772";
			conn = DriverManager.getConnection(url, username, password);
			stmt = conn.createStatement();

			String sqlFirst = "select count(1) from BankDB ID";
			rs = stmt.executeQuery(sqlFirst);
			while (rs.next()) {
				count = rs.getInt(1);
			}

			if (count == 0) {
				newcardId = 67400;
			} else {
				id = count + 1;
				newcardId = 67400 + id;
			}
			String blanckFirst = sc.nextLine();
			System.out.println("请输入你要创建的用户名:");
			name = sc.nextLine();
			System.out.println("请输入你要设置的密码:");
			psw = sc.nextInt();
			String blankSecond = sc.nextLine();
			System.out.println("请输入你的性别:");
			sex = sc.nextLine();
			System.out.println("您的卡号为" + newcardId);

			String sql = "Insert into BankDB (ID,CardID,Username,Sex,Password) values (" + id + "," + newcardId + ",'"
					+ name + "','" + sex + "'," + psw + ")";
			stmt.executeUpdate(sql);
			System.out.println("******您的信息已录入！******");
		} catch (Exception e) {
			System.out.println("******这里有一些错误哦~******");
			e.printStackTrace();
		} finally {
			if (rs != null)
				rs.close();
			if (stmt != null)
				stmt.close();
			if (conn != null)
				conn.close();
		}
	}

	public void SqlUserSave() throws SQLException {
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String admin = "root";
			String psw = "078772";
			conn = DriverManager.getConnection(url, admin, psw);
			stmt = conn.createStatement();

			String sql = "select * from BankDB CardID WHERE CardID = " + CardID + "";
			rs = stmt.executeQuery(sql);

			double balance = 0.00;
			double money = 0.00;
			while (rs.next()) {

				balance = rs.getDouble("Balance");
			}

			System.out.print("请输入您要存入的金额:");
			money = sc.nextDouble();

			if (money > 0) {
				balance = balance + money;
				String sqlChange = "update BankDB set Balance = " + balance + " WHERE CardID = " + CardID + " ";
				stmt.executeUpdate(sqlChange);
				System.out.println("******" + balance + "元已存入******");
			} else {
				System.out.println("****您的输入有误！****");
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null)
				conn.close();
			if (stmt != null)
				stmt.close();
			if (rs != null)
				rs.close();
		}
	}

	public void SqlUserWithdraw() throws SQLException {
		double money = 0.00;
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String admin = "root";
			String psw = "078772";
			conn = DriverManager.getConnection(url, admin, psw);
			stmt = conn.createStatement();

			String sql = "select * from BankDB CardID WHERE CardID = " + CardID + "";
			rs = stmt.executeQuery(sql);
			String name = null, password = null, sex = null;
			double balance = 0;
			while (rs.next()) {
				name = rs.getString("Username");
				password = rs.getString("Password");
				sex = rs.getString("Sex");
				balance = rs.getDouble("Balance");
			}

			System.out.println("****************************\n您的账户情况如下:");
			System.out.println("姓名：" + name);
			System.out.println("卡号：" + CardID);
			System.out.println("密码：" + password);
			System.out.println("性别：" + sex);
			System.out.println("余额：" + balance);
			System.out.println("***************************");

			System.out.print("请输入您要取出的金额:");
			money = sc.nextDouble();
			balance = balance - money;

			if (balance >= 0) {
				String sqlChange = "update BankDB set Balance = " + balance + " WHERE CardID = " + CardID + " ";
				stmt.executeUpdate(sqlChange);
				System.out.println("******" + balance + "元已取出******");
			} else {
				System.out.println("****您的账户里还没有这么多钱哦~努力挣钱吧~****");
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null)
				conn.close();
			if (stmt != null)
				stmt.close();
			if (rs != null)
				rs.close();
		}

	}

	public void SqlUserQuery() throws SQLException {

		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String admin = "root";
			String psw = "078772";
			conn = DriverManager.getConnection(url, admin, psw);
			stmt = conn.createStatement();

			String sql = "select * from BankDB CardID WHERE CardID = " + CardID + "";
			rs = stmt.executeQuery(sql);
			String name = null, sex = null;
			double balance = 0;
			int password = 0;
			while (rs.next()) {
				name = rs.getString("Username");
				password = rs.getInt("Password");
				sex = rs.getString("Sex");
				balance = rs.getDouble("Balance");
			}
			System.out.println("****************************\n您的账户情况如下:");
			System.out.println("姓名：" + name);
			System.out.println("卡号：" + CardID);
			System.out.println("密码：" + password);
			System.out.println("性别：" + sex);
			System.out.println("余额：" + balance);
			System.out.println("***************************");

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null)
				conn.close();
			if (stmt != null)
				stmt.close();
			if (rs != null)
				rs.close();
		}
	}

	public void SqlUserChangePsw() throws SQLException {
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String admin = "root";
			String psw = "078772";
			conn = DriverManager.getConnection(url, admin, psw);
			stmt = conn.createStatement();

			String sql = "select * from BankDB CardID WHERE CardID = " + CardID + "";
			rs = stmt.executeQuery(sql);
			String name = null, sex = null;
			int password = 0;
			while (rs.next()) {
				name = rs.getString("Username");
				password = rs.getInt("Password");
				sex = rs.getString("Sex");
			}
			System.out.println("****************************");
			while (true) {
				System.out.println("请重新输入您的密码:");
				int passwordtwice = sc.nextInt();

				if (passwordtwice == password) {

					System.out.println("***************************\n请输入您的新密码:");

					password = sc.nextInt();

					String sqlChange = "update BankDB set Password = " + password + " WHERE CardID = " + CardID + " ";
					stmt.executeUpdate(sqlChange);
					System.out.println("******尊敬的" + name + sex + "士您的密码已修改******");
					break;
				} else {
					System.out.println("有错误哦~请重新输入:");
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null)
				conn.close();
			if (stmt != null)
				stmt.close();
			if (rs != null)
				rs.close();
		}
	}
}

MYSQL类

package bank;

import java.io.RandomAccessFile;
import java.sql.*;
import java.util.Map;
import java.util.Scanner;


public class MySQL {
	Map<Integer, Users> users = BankDB.getDb().getUsers();
	public Users user;
	Object[] cardID = users.keySet().toArray();
	Scanner sc = new Scanner(System.in);
	
	Connection conn = null;
	Statement stmt = null;
	ResultSet rs = null;
	
	public void sqlStart() throws SQLException{

		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			String username = "root";
			String password = "078772";
			conn = DriverManager.getConnection(url,username,password);
			stmt = conn.createStatement();
		
		for (int i = 1;i<=users.size()-1;i++) {
			int cardId = Integer.parseInt(cardID[i].toString());
			user = BankDB.getDb().getUser(cardId);
			String sql = "Insert into BankDB (ID,CardID,Username,Sex,Password,Balance) values ("+i+","+cardID[i]+",'"+user.getName()+"','"+user.getSex()+"',"+user.getPassWord()+","+user.getBalance()+")";
			stmt.executeUpdate(sql);
		}
			//executeUpdate 增删改
			//查用executeQuery
		}catch(Exception e) {
			System.out.println("未能成功加载驱动程序，请检查是否导入驱动程序！");
			e.printStackTrace();
		}finally {
			if(rs!=null) rs.close();
			if(stmt!=null) stmt.close();
			if(conn!=null) conn.close();
		}
	}

	public void SqlAdminLogin() {
		System.out.println("查看全部成员的信息");
		//输入root账号密码查看全部信息
	}

	public void SqlAdminQuery() throws Exception {
		Connection conn = null;
		Statement stmt = null;
		ResultSet rs = null;
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/BankDB?useSSL=false&&serverTimezone=GMT%2B8";
			System.out.print("我们要先获得权限\n请输入您的用户名:");// root
			String name = sc.nextLine();
			System.out.print("请输入您的密码:");// 078772
			String psw = sc.nextLine();
			if (name.equals("root") && psw.equals("root")) {
				conn = DriverManager.getConnection(url, name, psw);
				stmt = conn.createStatement();

				String sqlSingle = "select * from BankDB ";
				System.out.println("亲爱的管理员，感谢您的到来！\n以下是数据库内的全部信息：");
				rs = stmt.executeQuery(sqlSingle);
				System.out.println("id\t|username\t|sex\t|cardId\t|password\t|balance\t|");
				while (rs.next()) {
					int id = rs.getInt(1);
					int password = rs.getInt("Password");
					String username = rs.getString("Username");
					String sex = rs.getString("Sex");
					int cardId = rs.getInt("CardID");
					int balance = rs.getInt("Balance");
					System.out.println(id + "\t|" + username + "\t|" + sex + "\t|" + cardId + "\t|" + password + "\t|"
							+ balance + "\t|");
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			conn.close();
			stmt.close();
			rs.close();
		}
	}


	public void runOneTime() throws Exception{
		try {
		RandomAccessFile raf = new RandomAccessFile("D:/a电子书/java/time/time.txt","rw");
		int times = Integer.parseInt(raf.readLine());
		if (times == 1) {
			sqlStart();
			System.out.println("成员信息已载入！");
			raf.seek(0);
			times = times - 1;
			raf.write((times+"").getBytes());
			raf.close();
		}else {
			System.out.println("****成员信息早就载入啦！****");
			raf.close();
			}
		}catch(Exception e) {
			e.printStackTrace();
		}
	}

}

BankDB类

package bank;

import java.util.HashMap;
import java.util.Map;

public class BankDB {
	Map<Integer,Users> users = new HashMap<>();
	private BankDB() {
		Users u1 = new Users("Emiya","女",67400,123456,1000);
		Users u2 = new Users("Reese","男",67401,654321,13000);
		Users u3 = new Users("Finch","男",67402,654321,100000);
		Users u4 = new Users("Cheshire","女",67403,18554,5200);
		Users u5 = new Users("Carter","女",67404,111111,1000);
		Users u6 = new Users("Root","女",67405,222222,2000);
		Users u7 = new Users("Shane","女",67406,333333,2000);
		Users u8 = new Users("Sunshine","女",67407,444444,9000);
		Users u9 = new Users("Morrian","女",67409,121212,1212);

		users.put(67400, u1);
		users.put(67401, u2);
		users.put(67402, u3);
		users.put(67403, u4);
		users.put(67404, u5);
		users.put(67405, u6);
		users.put(67406, u7);
		users.put(67407, u8);
		users.put(67408, u9);
	}
	static private BankDB db = new BankDB();
	
	public static BankDB getDb() {

		return db;
	}
	public static void setDb(BankDB db) {
		BankDB.db = db;
	}

	public Map<Integer, Users> getUsers() {
		return users;
	}
	public void setUsers(Map<Integer, Users> users) {
		this.users = users;
	}
	
	public Users getUser(Integer cardId) {//由cardId获得用户对象
		Users user = users.get(cardId);
		return user;
	}
	
	
}

Users类

package bank;

public class Users {
	private String name;
	private String sex;
	private int passWord;
	private int cardId;
	private int balance;
	private int interestType;
	private int time;
	public Users() {}
	public Users(String name,String sex,int cardId,int passWord,int balance) {
		//super();或许不需要
		this.balance = balance;
		this.passWord = passWord;
		this.name = name;
		this.sex = sex;
		this.cardId = cardId;
	}
	
	public int getBalance() {
		return balance;
	}
	public void setBalance(int balance) {
		this.balance = balance;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getCardId() {
		return cardId;
	}
	public void setCardId(int cardId) {
		this.cardId = cardId;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public int getPassWord() {
		return passWord;
	}
	public void setPassWord(int passWord) {
		this.passWord = passWord;
	}
	public int getInterestType() {
		return interestType;
	}
	public void setInterestType(int interestType) {
		this.interestType = interestType;
	}
	public int getTime() {
		return time;
	}
	public void setTime(int time) {
		this.time = time;
	}
	

} 

*******************************************以下是纯HashMap**********************************************

 BankDb、Users类都一样就不贴了

test类

package bank;

public class test {
	public static void main(String[] args) {
		operate o = new operate();
		o.login();
		o.menuSelect();
	}
}

operate类

package bank;

import java.util.*;

public class operate {
	Map<Integer, Users> users = BankDB.getDb().getUsers();
	Scanner sc = new Scanner(System.in);
	public Users user;

	public void login() {
		System.out.println("欢迎来到银行服务系统");
		while (true) {
			System.out.print("输入卡号:");
			int cardId = sc.nextInt();
			System.out.print("输入密码:");
			int passWord = sc.nextInt();
			user = BankDB.getDb().getUser(cardId);
			if (users.containsKey(cardId) && user.getPassWord() == passWord) {// equals是字符串
				System.out.println("欢迎" + user.getName() + user.getSex() + "士!");
				break;
			} else {
				System.out.println("或许你输入了什么奇怪的东西哦~");
			}
		}
	}// login

	public void menuSelect() {
		while (true) {
			System.out.println("1.查詢\n2.存款\n3.取款\n請輸入你的選擇:");
			int choice = sc.nextInt();
			switch (choice) {
			case 0: {
				System.out.println("真的要退出嗎？那就好好道個別吧bye~\n===============The end===============");
				return;
				}
			case 1: {
				query();
				break;
				}
			case 2:{
				saveMoney();
				break;
				}
			case 3:{
				withdrawMoney();
				break;
				}
			default:{
				System.out.println("您的輸入有問題哦~");
				break;
				}
			}
		}
	}

	public void query() {
		System.out.println("您當前的餘額:" + user.getBalance() + "元\n" + "特殊時期請保管好自己的口袋!");
	}

	public void saveMoney() {
		while (true) {
			System.out.print("想要存入多少钱呐~悄悄告诉我哦:");
			int num = sc.nextInt();

			if (num <= 0) {
				System.out.println("请检查你的输入~");
			} else {
				
				user.setBalance(num + user.getBalance());
				System.out.println("成功存入" + num + "元\n" + "目前余额为:" + user.getBalance());
			}
		}
	}

	public void withdrawMoney() {
		System.out.println("怎么，这么早就想把你的钱要回去了吗？说吧，想要多少？：");
		int num = sc.nextInt();
		if (num > user.getBalance()) {
			System.out.println("你可要挣更多钱哦~目前没有这么多钱躺在你的钱包里哦~");
		} else {
			user.setBalance(user.getBalance() - num);
			System.out.println("成功取出" + num + "元\n" + "目前余额为:" + user.getBalance());
		}
	}
}

就只是留个纪念啦~有一个比较好一些的类似的是小组作业，但毕竟不是我个人所有啦~

反正还有很多要进步的地方，加油！