随机验证码

随机验证码

//    生成随机验证码
    public static String createCode(int n) {
        String code = "";
        Random r = new Random();
        for (int i = 0; i < n; i++) {
            int type = r.nextInt(3);
            switch (type) {
                case 0:
//                   大写字符 (A 65 - Z 65+25)
                    char ch = (char) (r.nextInt(26) + 65);
                    code += ch;
                    break;
                case 1:
//                   小写字符 (a 97 - z 97+25)
                    char ch1 = (char) (r.nextInt(26) + 97);
                    code += ch1;
                    break;
                case 2:
//                   数字
                    code += r.nextInt(10);
                    break;
            }
        }
        return code;
    }
}