生成六位数字验证码

生成六位数字验证码，仅供参考。

public static String getAppCode() {

int n = 6;
StringBuilder code = new StringBuilder();
Random ran = new Random();
for (int i = 0; i < n; i++) {
code.append(Integer.valueOf(ran.nextInt(10)).toString());
}
return code.toString();
}