JAVA入门必做小项目：模拟ATM系统

不看后悔系列

模拟银行开户、存款、取款、转账、修改密码、注销账户等功能，其中还有生成随机验证码等小功能，蕴含很多逻辑，非常适合初学JAVA的选手，为后面的面向对象进阶学习打下基础！
（说明：内容学自黑马，感觉这个案例不错就写出来分享一下，若有侵权请联系删除）

只有两个JAVA文件，源码如下：
（具体运行效果比较长就不放图片了，只需你复制粘贴运行一下就可啦）

/**
    系统的账户类，代表账户的信息
 */
public class Account {
    
    
    private String cardId; // 卡号
    private String userName; // 用户名称
    private String passWord; // 密码
    private double money; // 账户余额
    private double quotaMoney; // 每次取现额度限度。

    public String getCardId() {
    
    
        return cardId;
    }

    public void setCardId(String cardId) {
    
    
        this.cardId = cardId;
    }

    public String getUserName() {
    
    
        return userName;
    }

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

    public String getPassWord() {
    
    
        return passWord;
    }

    public void setPassWord(String passWord) {
    
    
        this.passWord = passWord;
    }

    public double getMoney() {
    
    
        return money;
    }

    public void setMoney(double money) {
    
    
        this.money = money;
    }

    public double getQuotaMoney() {
    
    
        return quotaMoney;
    }

    public void setQuotaMoney(double quotaMoney) {
    
    
        this.quotaMoney = quotaMoney;
    }
}

/**
 * @description：ATM系统模拟
 * @version: 1.0
 */
public class ATMSystemExercise {
    
    
    public static void main(String[] args) {
    
    
        //准备一个账户集合 存储账户对象
        ArrayList<Account> accounts = new ArrayList<>();
        //进入系统首页
        showMain(accounts);
    }

    //系统首页
    public static void showMain(ArrayList<Account> accounts) {
    
    
        while (true) {
    
    
            System.out.println("==================欢迎您进入到ATM模拟系统===============");
            System.out.println("1、登录账户");
            System.out.println("2、注册账户");
            System.out.println("请您输入1、2选择操作：");
            Scanner sc = new Scanner(System.in);
            int command = sc.nextInt();
            switch (command) {
    
    
                case 1:
                    //登录
                    login(accounts, sc);
                    break;
                case 2:
                    //开户
                    register(accounts, sc);
                    break;
                default:
                    System.out.println("输入命令有误！");
            }
        }
    }

    /**
     * 用户登录
     *
     * @param accounts 账户的集合对象
     * @param sc       扫描器对象
     */
    private static void login(ArrayList<Account> accounts, Scanner sc) {
    
    
        if (accounts.size() > 0) {
    
    
            System.out.println("==================欢迎您进入到登录页面==================");
            while (true) {
    
    
                System.out.println("请您输入登录的卡号：");
                String cardId = sc.next();
                Account acc = getAccountByCardId(accounts, cardId);
                if (acc == null) {
    
    
                    System.out.println("您输入的卡号不存在，请重新输入");
                } else {
    
    
                    while (true) {
    
    
                        System.out.println("请您输入登录密码：");
                        String password = sc.next();
                        if (password.equals(acc.getPassWord())) {
    
    
                            System.out.println("欢迎" + acc.getUserName() + "先生/女士进入系统，您可开始办理你的业务了!");
                            //showCommand()进入操作页面
                            showCommand(acc, sc, accounts);
                            return;
                        } else {
    
    
                            System.out.println("您的密码不正确！");
                        }
                    }
                }

            }
        } else {
    
    
            System.out.println("当前系统无任何账户，请先注册再登录！");
        }
    }

    /**
     * 账户登陆成功的操作页面
     *
     * @param acc
     * @param sc
     */
    private static void showCommand(Account acc, Scanner sc, ArrayList<Account> accounts) {
    
    
        while (true) {
    
    
            System.out.println("==================欢迎您进入到操作界面==================");
            System.out.println("1、查询");
            System.out.println("2、存款");
            System.out.println("3、取款");
            System.out.println("4、转账");
            System.out.println("5、修改密码");
            System.out.println("6、退出账户");
            System.out.println("7、注销账户");
            System.out.println("请您输入操作命令：");
            int command = sc.nextInt();
            switch (command) {
    
    
                case 1:
                    //查询
                    showUserMessage(acc);
                    break;
                case 2:
                    //存款
                    depositMoney(acc, sc);
                    break;
                case 3:
                    //取款
                    drawMoney(acc, sc);
                    break;
                case 4:
                    //转账
                    transferMoney(accounts, acc, sc);
                    break;
                case 5:
                    //修改密码
                    updatePassword(acc, sc);
                    break;
                case 6:
                    //退出账户
                    System.out.println("已安全退出，欢迎下次光临！");
                    return;
                case 7:
                    //注销账户
                    logoutAccount(accounts, acc, sc);
                    return;
                default:
                    System.out.println("请输入正确的数字指令1-7");
                    break;
            }
        }
    }

    /**
     * 转账
     *
     * @param accounts
     * @param acc
     * @param sc
     */
    private static void transferMoney(ArrayList<Account> accounts, Account acc, Scanner sc) {
    
    
        System.out.println("==================欢迎您进入转账操作页面==================");
        System.out.println("请您输入收款人账号");
        while (true) {
    
    
            String cardId = sc.next();
            if ("-1".equals(cardId)) {
    
    
                return;
            }
            Account otherAcc = getAccountByCardId(accounts, cardId);
            if (otherAcc != null) {
    
    
                String name = otherAcc.getUserName();
                System.out.println("请输入对方姓氏进行认证：【*" + name.substring(1) + "】");
                String surname = sc.next();
                if (name.startsWith(surname)) {
    
    
                    System.out.println("身份验证成功，请您输入转账金额：");
                    while (true) {
    
    
                        double money = sc.nextDouble();
                        if (money <= acc.getMoney()) {
    
    
                            acc.setMoney(acc.getMoney() - money);
                            otherAcc.setMoney(otherAcc.getMoney() + money);
                            System.out.println("转账成功，卡内余额：" + acc.getMoney() + "元");
                            return;
                        } else {
    
    
                            System.out.println("账户余额不足，你只有" + acc.getMoney() + "元,是否要重新输入金额？ Y/N");
                            String choose = sc.next();
                            if ("Y".equalsIgnoreCase(choose)) {
    
    
                                System.out.println("请您输入转账金额:");
                            } else if ("N".equalsIgnoreCase(choose)) {
    
    
                                return;
                            }
                        }
                    }
                } else {
    
    
                    System.out.println("身份认证失败，返回操作页面");
                    return;
                }
            } else {
    
    
                System.out.println("账户不存在，请重新输入：(可输入 -1 返回操作界面)");
            }
        }
    }

    /**
     * 销户功能
     *
     * @param accounts
     * @param acc
     * @param sc
     */
    private static void logoutAccount(ArrayList<Account> accounts, Account acc, Scanner sc) {
    
    
        int count = 0;
        String verificationCode = createVerificationCode();
        System.out.println("请您输入验证码“" + verificationCode + "“");
        while (true) {
    
    
            String code = sc.next();
            if (code.equalsIgnoreCase(verificationCode)) {
    
    
                accounts.remove(acc);
                System.out.println("注销账户成功");
                return;
            } else {
    
    
                if (count < 2) {
    
    
                    count++;
                    System.out.println("验证码输入失败，请重新输入：");
                } else {
    
    
                    System.out.println("您已错误三次，怀疑是非法操作，将自动退出系统");
                    return;
                }
            }
        }
    }

    /**
     * 更改密码
     *
     * @param acc
     * @param sc
     */
    private static void updatePassword(Account acc, Scanner sc) {
    
    
        System.out.println("==================欢迎进入更改密码页面======================");
        System.out.println("请您输入当前密码进行认证");
        while (true) {
    
    
            String password = sc.next();
            if (password.equals(acc.getPassWord())) {
    
    
                while (true) {
    
    
                    System.out.println("请输入新密码：");
                    String newPassword = sc.next();
                    System.out.println("请您再次输入新密码：");
                    String okPassword = sc.next();
                    if (okPassword.equals(newPassword)) {
    
    
                        System.out.println("密码修改成功");
                        return;
                    } else {
    
    
                        System.out.println("两次密码不一致");
                    }
                }
            } else {
    
    
                System.out.println("密码输入错误，请重新输入");
            }
        }
    }

    /**
     * 生成6位的验证码用来销户前的人机验证
     *
     * @return
     */
    private static String createVerificationCode() {
    
    
        Random r = new Random();
        String s = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        String code = "";
        for (int i = 0; i < 6; i++) {
    
    
            code += s.charAt(r.nextInt(s.length()));
        }
        return code;
    }

    /**
     * 取款
     *
     * @param acc
     * @param sc
     */
    private static void drawMoney(Account acc, Scanner sc) {
    
    
        System.out.println("==================欢迎您进入账户取款页面======================");
        if (acc.getMoney() > 0) {
    
    
            while (true) {
    
    
                System.out.println("请您输入取款金额：");
                double money = sc.nextDouble();
                if (money > acc.getMoney()) {
    
    
                    System.out.println("余额不足，您卡上余额只有" + acc.getMoney() + "元");
                } else {
    
    
                    if (money > acc.getQuotaMoney()) {
    
    
                        System.out.println("取款数额超过您的单次取款额度" + acc.getQuotaMoney() + "元");
                    } else {
    
    
                        acc.setMoney(acc.getMoney() - money);
                        System.out.println("取款完成，卡内余额:" + acc.getMoney() + "元");
                        break;
                    }
                }
            }
        } else {
    
    
            System.out.println("卡内无余额可取");
        }
    }

    /**
     * 存款
     *
     * @param acc
     * @param sc
     */
    private static void depositMoney(Account acc, Scanner sc) {
    
    
        System.out.println("==================欢迎您进入账户存款页面======================");
        System.out.println("请您输入存款金额：");
        double money = sc.nextDouble();
        acc.setMoney(money + acc.getMoney());
        System.out.println(money + "元存款成功");
        showUserMessage(acc);
    }

    /**
     * 展示用户信息页面
     *
     * @param acc
     */
    private static void showUserMessage(Account acc) {
    
    
        System.out.println("==================您当前账户详情信息如下==================");
        System.out.println("卡号：" + acc.getCardId());
        System.out.println("户主：" + acc.getUserName());
        System.out.println("余额：" + acc.getMoney());
        System.out.println("当次取现额度：" + acc.getQuotaMoney());
    }

    /**
     * 用户开户功能
     *
     * @param accounts 账户的集合对象
     * @param sc       扫描器对象
     */
    private static void register(ArrayList<Account> accounts, Scanner sc) {
    
    
        Account acc = new Account();
        System.out.println("==================欢迎您进入到开户页面======================");
        System.out.println("请您输入账户名称");
        String username = sc.next();
        acc.setUserName(username);
        while (true) {
    
    
            System.out.println("请您输入账户密码：");
            String passWord = sc.next();
            System.out.println("请您输入确认密码：");
            String okPassWord = sc.next();
            if (okPassWord.equals(passWord)) {
    
    
                // 密码无问题
                acc.setPassWord(okPassWord);
                break;
            } else {
    
    
                System.out.println("两次输入的密码不一致！");
            }
        }
        String cardId = createCardId(accounts);
        acc.setCardId(cardId);
        System.out.println("请您设置当次取现额度：");
        double quotaMoney = sc.nextDouble();
        acc.setQuotaMoney(quotaMoney);
        accounts.add(acc);
        System.out.println(acc.getUserName() + "，恭喜您开户完成，您的卡号是：" + acc.getCardId());
    }

    /**
     * 生成8位的随机数字不重复卡号
     *
     * @param accounts
     * @return
     */
    private static String createCardId(ArrayList<Account> accounts) {
    
    
        Random r = new Random();
        String cardId = "";
        while (true) {
    
    
            cardId = "";
            for (int i = 0; i < 8; i++) {
    
    
                cardId += r.nextInt(10);
            }
            Account acc = getAccountByCardId(accounts, cardId);
            if (acc == null) {
    
    
                return cardId;
            }
        }
    }

    /**
     * 通过卡号找用户
     *
     * @param accounts
     * @param cardId
     * @return
     */
    private static Account getAccountByCardId(ArrayList<Account> accounts, String cardId) {
    
    
        for (int i = 0; i < accounts.size(); i++) {
    
    
            Account acc = accounts.get(i);
            if (cardId.equals(acc.getCardId())) {
    
    
                return acc;
            }
        }
        return null;
    }
}