用Java编写一个银行ATM机模拟系统，实现账户管理，存钱，取钱，转账，销户等操作。账户数据保存在Mysql数据库中

好的，下面是一个简单的银行ATM机模拟系统的Java代码，实现了账户管理，存钱，取钱，转账，销户等操作，并且使用了Mysql数据库保存账户数据。

import java.sql.*;

public class ATMSystem {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/atm";
    private static final String USER = "root";
    private static final String PASS = "password";
    private static Connection conn = null;

    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(DB_URL, USER, PASS);
            System.out.println("Connected to database successfully!");
            createTable();
            menu();
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private static void createTable() {
        try {
            Statement stmt = conn.createStatement();
            String sql = "CREATE TABLE IF NOT EXISTS accounts " +
                    "(id INTEGER not NULL AUTO_INCREMENT," +
                    " name VARCHAR(255)," +
                    " balance DOUBLE," +
                    " PRIMARY KEY ( id ))";
            stmt.executeUpdate(sql);
            System.out.println("Table created successfully!");
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private static void menu() {
        int choice;
        do {
            System.out.println("\nWelcome to ATM System!");
            System.out.println("1. Create Account");
            System.out.println("2. Deposit Money");
            System.out.println("3. Withdraw Money");
            System.out.println("4. Transfer Money");
            System.out.println("5. Close Account");
            System.out.println("6. Exit");

            choice = Input.getInteger("Enter your choice: ");

            switch (choice) {
                case 1:
                    createAccount();
                    break;
                case 2:
                    depositMoney();
                    break;
                case 3:
                    withdrawMoney();
                    break;
                case 4:
                    transferMoney();
                    break;
                case 5:
                    closeAccount();
                    break;
                case 6:
                    System.out.println("Goodbye!");
                    break;
                default:
                    System.out.println("Invalid choice!");
            }
        } while (choice != 6);
    }

    private static void createAccount() {
        String name = Input.getString("Enter your name: ");
        double balance = Input.getDouble("Enter your initial balance: ");

        try {
            PreparedStatement pstmt = conn.prepareStatement("INSERT INTO accounts (name, balance) VALUES (?, ?)");
            pstmt.setString(1, name);
            pstmt.setDouble(2, balance);
            pstmt.executeUpdate();
            System.out.println("Account created successfully!");
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private static void depositMoney() {
        int id = Input.getInteger("Enter your account ID: ");
        double amount = Input.getDouble("Enter the amount to deposit: ");

        try {
            PreparedStatement pstmt = conn.prepareStatement("UPDATE accounts SET balance = balance + ? WHERE id = ?");
            pstmt.setDouble(1, amount);
            pstmt.setInt(2, id);
            int rowsUpdated = pstmt.executeUpdate();
            if (rowsUpdated > 0) {
                System.out.println("Amount deposited successfully!");
            } else {
                System.out.println("Account not found!");
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private static void withdrawMoney() {
        int id = Input.getInteger("Enter your account ID: ");
        double amount = Input.getDouble("Enter the amount to withdraw: ");

        try {
            PreparedStatement pstmt = conn.prepareStatement("SELECT balance FROM accounts WHERE id = ?");
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                double balance = rs.getDouble("balance");
                if (balance >= amount) {
                    pstmt = conn.prepareStatement("UPDATE accounts SET balance = balance - ? WHERE id = ?");
                    pstmt.setDouble(1, amount);
                    pstmt.setInt(2, id);
                    int rowsUpdated = pstmt.executeUpdate();
                    if (rowsUpdated > 0) {
                        System.out.println("Amount withdrawn successfully!");
                    } else {
                        System.out.println("Account not found!");
                    }
                } else {
                    System.out.println("Insufficient balance!");
                }
            } else {
                System.out.println("Account not found!");
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private static void transferMoney() {
        int fromId = Input.getInteger("Enter your account ID: ");
        int toId = Input.getInteger("Enter the recipient's account ID: ");
        double amount = Input.getDouble("Enter the amount to transfer: ");

        try {
            PreparedStatement pstmt = conn.prepareStatement("SELECT balance FROM accounts WHERE id = ?");
            pstmt.setInt(1, fromId);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                double fromBalance = rs.getDouble("balance");
                if (fromBalance >= amount) {
                    pstmt = conn.prepareStatement("SELECT balance FROM accounts WHERE id = ?");
                    pstmt.setInt(1, toId);
                    rs = pstmt.executeQuery();
                    if (rs.next()) {
                        double toBalance = rs.getDouble("balance");
                        pstmt = conn.prepareStatement("UPDATE accounts SET balance = balance - ? WHERE id = ?");
                        pstmt.setDouble(1, amount);
                        pstmt.setInt(2, fromId);
                        int rowsUpdated1 = pstmt.executeUpdate();
                        pstmt = conn.prepareStatement("UPDATE accounts SET balance = balance + ? WHERE id = ?");
                        pstmt.setDouble(1, amount);
                        pstmt.setInt(2, toId);
                        int rowsUpdated2 = pstmt.executeUpdate();
                        if (rowsUpdated1 > 0 && rowsUpdated2 > 0) {
                            System.out.println("Amount transferred successfully!");
                        } else {
                            System.out.println("Account not found!");
                        }
                    } else {
                        System.out.println("Recipient's account not found!");
                    }
                } else {
                    System.out.println("Insufficient balance!");
                }
            } else {
                System.out.println("Account not found!");
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private static void closeAccount() {
        int id = Input.getInteger("Enter your account ID: ");

        try {
            PreparedStatement pstmt = conn.prepareStatement("DELETE FROM accounts WHERE id = ?");
            pstmt.setInt(1, id);
            int rowsDeleted = pstmt.executeUpdate();
            if (rowsDeleted > 0) {
                System.out.println("Account closed successfully!");
            } else {
                System.out.println("Account not found!");
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }
}

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

    public static int getInteger(String prompt) {
        int value;
        do {
            System.out.print(prompt);
            while (!scanner.hasNextInt()) {
                System.out.println("Invalid input!");
                scanner.next();
            }
            value = scanner.nextInt();
        } while (value < 0);
        return value;
    }

    public static double getDouble(String prompt) {
        double value;
        do {
            System.out.print(prompt);
            while (!scanner.hasNextDouble()) {
                System.out.println("Invalid input!");
                scanner.next();
            }
            value = scanner.nextDouble();
        } while (value < 0);
        return value;
    }

    public static String getString(String prompt) {
        System.out.print(prompt);
        return scanner.nextLine();
    }
}

在上述代码中，我们使用了Java的JDBC API来连接Mysql数据库，并实现了账户管理，存钱，取钱，转账，销户等操作。同时，我们使用了Input类来获取用户输入的整数、小数和字符串。

请注意，在运行此代码之前，需要确保您已经正确安装了Mysql，并创建了名为“atm”的数据库。另外，您需要将代码中的数据库连接URL、用户名和密码替换为您自己的值。