完整Java银行代码实现

以下是一个较为完整的 Java 银行系统代码实现，实现了存款、取款、转账、查询余额、查询交易记录等功能。代码中使用了面向对象的编程思想和设计模式，同时对数据进行了封装和安全控制，提高了系统的可靠性和稳定性。

import java.util.ArrayList;
import java.util.Date;
import java.util.Scanner;

/**
 * 银行账户类
 */
class Account {
    private String id; // 账户编号
    private String name; // 账户名称
    private String password; // 账户密码
    private double balance; // 账户余额
    private ArrayList<Transaction> transactions; // 交易记录

    public Account(String id, String name, String password) {
        this.id = id;
        this.name = name;
        this.password = password;
        this.balance = 0;
        this.transactions = new ArrayList<>();
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    // 存款
    public void deposit(double amount) {
        balance += amount;
        transactions.add(new Transaction(new Date(), 'D', amount, balance));
    }

    // 取款
    public void withdraw(double amount) {
        if (balance < amount) {
            System.out.println("余额不足！");
        } else {
            balance -= amount;
            transactions.add(new Transaction(new Date(), 'W', amount, balance));
        }
    }

    // 转账
    public void transfer(Account target, double amount) {
        if (balance < amount) {
            System.out.println("余额不足！");
        } else {
            balance -= amount;
            target.balance += amount;
            transactions.add(new Transaction(new Date(), 'T', amount, balance, target.getId()));
        }
    }

    public double getBalance() {
        return balance;
    }

    // 查询交易记录
    public void printTransactions() {
        for (Transaction transaction : transactions) {
            System.out.println(transaction.toString());
        }
    }

    // 验证密码是否正确
    public boolean validatePassword(String password) {
        return this.password.equals(password);
    }
}

/**
 * 交易记录类
 */
class Transaction {
    private Date date; // 交易日期
    private char type; // 交易类型（D：存款，W：取款，T：转账）
    private double amount; // 交易金额
    private double balance; // 余额
    private String targetId; // 目标账户编号（仅在转账时使用）

    public Transaction(Date date, char type, double amount, double balance) {
        this.date = date;
        this.type = type;
        this.amount = amount;
        this.balance = balance;
    }

    public Transaction(Date date, char type, double amount, double balance, String targetId) {
        this.date = date;
        this.type = type;
        this.amount = amount;
        this.balance = balance;
        this.targetId = targetId;
    }

    @Override
    public String toString() {
        return "Transaction{" +
                "date=" + date +
                ", type=" + type +
                ", amount=" + amount +
                ", balance=" + balance +
                (targetId != null ? ", targetId='" + targetId + '\'' : "") +
                '}';
    }
}

/**
 * 银行系统类
 */
public class BankSystem {
    private ArrayList<Account> accounts; // 所有账户

    public BankSystem() {
        this.accounts = new ArrayList<>();
    }

    // 创建账户
    public void createAccount(String id, String name, String password) {
        accounts.add(new Account(id, name, password));
    }

    // 登录账户
    public Account loginAccount(String id, String password) {
        for (Account account : accounts) {
            if (account.getId().equals(id) && account.validatePassword(password)) {
                return account;
            }
        }
        return null;
    }

    public static void main(String[] args) {
        BankSystem bank = new BankSystem();
        Scanner scanner = new Scanner(System.in);
        Account currentAccount = null;

        while (true) {
            if (currentAccount == null) {
                System.out.println("欢迎使用银行系统，请选择操作：");
                System.out.println("1. 创建账户");
                System.out.println("2. 登录账户");
                System.out.println("3. 退出");
                System.out.print("请选择操作编号：");
                int option = scanner.nextInt();
                if (option == 1) {
                    System.out.print("请输入账户编号：");
                    String id = scanner.next();
                    System.out.print("请输入账户名称：");
                    String name = scanner.next();
                    System.out.print("请输入账户密码：");
                    String password = scanner.next();
                    bank.createAccount(id, name, password);
                    System.out.println("账户创建成功！");
                } else if (option == 2) {
                    System.out.print("请输入账户编号：");
                    String id = scanner.next();
                    System.out.print("请输入账户密码：");
                    String password = scanner.next();
                    currentAccount = bank.loginAccount(id, password);
                    if (currentAccount == null) {
                        System.out.println("登录失败，请检查账户编号和密码！");
                    } else {
                        System.out.println("登录成功，欢迎 " + currentAccount.getName() + "！");
                    }
                } else if (option == 3) {
                    break;
                } else {
                    System.out.println("输入有误，请重新输入！");
                }
            } else {
                System.out.println("请选择操作：");
                System.out.println("1. 存款");
                System.out.println("2. 取款");
                System.out.println("3. 转账");
                System.out.println("4. 查询余额");
                System.out.println("5. 查询交易记录");
                System.out.println("6. 退出登录");
                System.out.print("请选择操作编号：");
                int option = scanner.nextInt();
                if (option == 1) {
                    System.out.print("请输入存款金额：");
                    double amount = scanner.nextDouble();
                    currentAccount.deposit(amount);
                    System.out.println("存款成功！当前余额为：" + currentAccount.getBalance());
                } else if (option == 2) {
                    System.out.print("请输入取款金额：");
                    double amount = scanner.nextDouble();
                    currentAccount.withdraw(amount);
                    System.out.println("取款成功！当前余额为：" + currentAccount.getBalance());
                } else if (option == 3) {
                    System.out.print("请输入转账金额：");
                    double amount = scanner.nextDouble();
                    System.out.print("请输入目标账户编号：");
                    String targetId = scanner.next();
                    Account targetAccount = null;
                    for (Account account : bank.accounts) {
                        if (account.getId().equals(targetId)) {
                            targetAccount = account;
                            break;
                        }
                    }
                    if (targetAccount == null) {
                        System.out.println("目标账户不存在！");
                    } else {
                        currentAccount.transfer(targetAccount, amount);
                        System.out.println("转账成功！当前余额为：" + currentAccount.getBalance());
                    }
                } else if (option == 4) {
                    System.out.println("当前余额为：" + currentAccount.getBalance());
                } else if (option == 5) {
                    System.out.println("交易记录如下：");
                    currentAccount.printTransactions();
                } else if (option == 6) {
                    System.out.println("退出登录成功！");
                    currentAccount = null;
                } else {
                    System.out.println("输入有误，请重新输入！");
                }
            }
        }
        scanner.close();
    }
}

这个完整的银行系统代码实现了基本的存款、取款、转账、查询余额和查询交易记录等功能，同时对数据进行了封装和安全控制，提高了系统的可靠性和稳定性。需要注意的是，这只是一个简单的示例，实际的银行系统需要更多的功能和安全措施。