用Java写出验证码

public class Until {
    
    public static String createVerifycode(int n) {
        //开发一个验证码
        //定义一个变量记住验证码
        String code = "";
        //定义一个变量记住全部字符
        String data = "qwetyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM0123456789";
        //定义一个循环变量生成几个随机索引，去得到几个字符
        Random r = new Random();
        for (int i = 0; i < n; i++) {
            //获取随机索引引对应的字符，链接给code
            int index = r.nextInt(data.length());
            code += data.charAt(index);
        }
        return code;
    }
}

public class Login {
    public static void main(String[] args) {
        System.out.println("需要几位数的验证码");
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(Until.createVerifycode(n));

    }
}