java课程设计银行存取款操作系统

以下是一个Java银行存取款操作系统的简单实现，包括用户注册、登录、修改密码、余额查询、充值、转账和取款等功能。该系统使用MySQL数据库存储用户信息和交易记录，并采用正则表达式对用户输入进行规范化处理。

import java.sql.*;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class BankSystem {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/bank";
    private static final String DB_USER = "root";
    private static final String DB_PASSWORD = "123456";

    private static Connection conn = null;
    private static Statement stmt = null;
    private static ResultSet rs = null;

    private static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
            stmt = conn.createStatement();
            System.out.println("欢迎使用银行存取款管理系统！");
            while (true) {
                System.out.println("请选择操作：");
                System.out.println("1.用户注册 2.用户登录 3.退出系统");
                int choice = scanner.nextInt();
                scanner.nextLine();
                switch (choice) {
                    case 1:
                        register();
                        break;
                    case 2:
                        login();
                        break;
                    case 3:
                        System.out.println("感谢使用银行存取款管理系统！");
                        System.exit(0);
                    default:
                        System.out.println("无效的选择，请重新输入！");
                }
            }
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) rs.close();
                if (stmt != null) stmt.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    private static void register() throws SQLException {
        System.out.println("请输入用户名：");
        String username = scanner.nextLine();
        if (usernameExists(username)) {
            System.out.println("该用户名已存在，请重新输入！");
            return;
        }
        System.out.println("请输入密码：");
        String password = scanner.nextLine();
        if (!isValidPassword(password)) {
            System.out.println("密码不符合规范，请重新输入！");
            return;
        }
        System.out.println("请输入初始余额：");
        double balance = scanner.nextDouble();
        scanner.nextLine();
        String sql = "INSERT INTO users (username, password, balance) VALUES ('" + username + "', '" + password + "', " + balance + ")";
        stmt.executeUpdate(sql);
        System.out.println("注册成功！");
    }

    private static void login() throws SQLException {
        System.out.println("请输入用户名：");
        String username = scanner.nextLine();
        if (!usernameExists(username)) {
            System.out.println("该用户名不存在，请重新输入！");
            return;
        }
        System.out.println("请输入密码：");
        String password = scanner.nextLine();
        String sql = "SELECT * FROM users WHERE username='" + username + "' AND password='" + password + "'";
        rs = stmt.executeQuery(sql);
        if (rs.next()) {
            System.out.println("登录成功！");
            while (true) {
                System.out.println("请选择操作：");
                System.out.println("1.修改密码 2.余额查询 3.充值 4.转账 5.取款 6.返回上一级");
                int choice = scanner.nextInt();
                scanner.nextLine();
                switch (choice) {
                    case 1:
                        changePassword(username);
                        break;
                    case 2:
                        checkBalance(username);
                        break;
                    case 3:
                        deposit(username);
                        break;
                    case 4:
                        transfer(username);
                        break;
                    case 5:
                        withdraw(username);
                        break;
                    case 6:
                        return;
                    default:
                        System.out.println("无效的选择，请重新输入！");
                }
            }
        } else {
            System.out.println("密码错误，请重新输入！");
        }
    }

    private static void changePassword(String username) throws SQLException {
        System.out.println("请输入旧密码：");
        String oldPassword = scanner.nextLine();
        String sql = "SELECT * FROM users WHERE username='" + username + "' AND password='" + oldPassword + "'";
        rs = stmt.executeQuery(sql);
        if (rs.next()) {
            System.out.println("请输入新密码：");
            String newPassword = scanner.nextLine();
            if (!isValidPassword(newPassword)) {
                System.out.println("密码不符合规范，请重新输入！");
                return;
            }
            sql = "UPDATE users SET password='" + newPassword + "' WHERE username='" + username + "'";
            stmt.executeUpdate(sql);
            System.out.println("密码修改成功！");
        } else {
            System.out.println("旧密码错误，请重新输入！");
        }
    }

    private static void checkBalance(String username) throws SQLException {
        String sql = "SELECT balance FROM users WHERE username='" + username + "'";
        rs = stmt.executeQuery(sql);
        if (rs.next()) {
            double balance = rs.getDouble("balance");
            System.out.println("当前余额为：" + balance);
        }
    }

    private static void deposit(String username) throws SQLException {
        System.out.println("请输入充值金额：");
        double amount = scanner.nextDouble();
        scanner.nextLine();
        String sql = "UPDATE users SET balance=balance+" + amount + " WHERE username='" + username + "'";
        stmt.executeUpdate(sql);
        sql = "INSERT INTO transactions (username, type, amount) VALUES ('" + username + "', '充值', " + amount + ")";
        stmt.executeUpdate(sql);
        System.out.println("充值成功！");
    }

    private static void transfer(String username) throws SQLException {
        System.out.println("请输入对方用户名：");
        String toUsername = scanner.nextLine();
        if (!usernameExists(toUsername)) {
            System.out.println("该用户名不存在，请重新输入！");
            return;
        }
        System.out.println("请输入转账金额：");
        double amount = scanner.nextDouble();
        scanner.nextLine();
        String sql = "SELECT balance FROM users WHERE username='" + username + "'";
        rs = stmt.executeQuery(sql);
        if (rs.next()) {
            double balance = rs.getDouble("balance");
            if (balance < amount) {
                System.out.println("余额不足，转账失败！");
                return;
            }
            sql = "UPDATE users SET balance=balance-" + amount + " WHERE username='" + username + "'";
            stmt.executeUpdate(sql);
            sql = "UPDATE users SET balance=balance+" + amount + " WHERE username='" + toUsername + "'";
            stmt.executeUpdate(sql);
            sql = "INSERT INTO transactions (username, type, amount) VALUES ('" + username + "', '转账', -" + amount + ")";
            stmt.executeUpdate(sql);
            sql = "INSERT INTO transactions (username, type, amount) VALUES ('" + toUsername + "', '转账', " + amount + ")";
            stmt.executeUpdate(sql);
            System.out.println("转账成功！");
        }
    }

    private static void withdraw(String username) throws SQLException {
        System.out.println("请输入取款金额：");
        double amount = scanner.nextDouble();
        scanner.nextLine();
        String sql = "SELECT balance FROM users WHERE username='" + username + "'";
        rs = stmt.executeQuery(sql);
        if (rs.next()) {
            double balance = rs.getDouble("balance");
            if (balance < amount) {
                System.out.println("余额不足，取款失败！");
                return;
            }
            sql = "UPDATE users SET balance=balance-" + amount + " WHERE username='" + username + "'";
            stmt.executeUpdate(sql);
            sql = "INSERT INTO transactions (username, type, amount) VALUES ('" + username + "', '取款', -" + amount + ")";
            stmt.executeUpdate(sql);
            System.out.println("取款成功！");
        }
    }

    private static boolean usernameExists(String username) throws SQLException {
        String sql = "SELECT * FROM users WHERE username='" + username + "'";
        rs = stmt.executeQuery(sql);
        return rs.next();
    }

    private static boolean isValidPassword(String password) {
        String regex = "^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%^&+=])(?=\\S+$).{8,}$";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(password);
        return matcher.matches();
    }
}