【java】生成随机验证码方法

public class VerificationCode {
    /*
        生成随机验证码
     */
    public static void main(String[] args) {
        String code = generationVeriCode(6);
        System.out.println("验证码:" + code);
    }
    public static String generationVeriCode(int len){
        String code = "";
        char[] chs = {'a','b','c','d','e','f','g','h','i','g','k','l','m',
                        'n','o','p','q','r','s','t','u','v','w','x','y','z',
                        'A','B','C','D','E','F','G','H','I','J','K','L','M',
                        'N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
                        '0','1','2','3','4','5','6','7','8','9'};
        Random rand = new Random();
        for (int i=1;i<=len;i++){
            //int index = (int)(Math.random()* chs.length);
            int index = rand.nextInt(chs.length);
            code += chs[index];
        }
        return code;
    }
}