获取随机字符串（0~9，A~Z）

/// <summary>
        /// 生成随机数
        /// </summary>
        /// <param name="codeLen">数据的长度</param>
        /// <returns></returns>
        public string CreateRandomCode(int codeLen)
        {
            string allChar = "0,1,2,3,4,5,6,7,8,9,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";// 若想生成验证码则通常会去掉类似的字符，如：O与0、I与1
            string[] allCharAry = allChar.Split(',');
            string randomCode = "";
            int temp = -1;
            Random rand = new Random();
            for (int i = 0; i < codeLen; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * ((int)DateTime.Now.Ticks));// 保证随机性跟严谨
                }
                int t = rand.Next(35);// allChar数组索引最大值
                if (temp == t)
                {
                    return CreateRandomCode(codeLen);//防止随机字符串中两个相邻的字符相等
                }
                temp = t;
                randomCode += allCharAry[t];
            }
            return randomCode;
        }