/// <summary>   
        /// 截取文本，区分中英文字符，中文算两个长度，英文算一个长度
        /// </summary>
        /// <param name="str">待截取的字符串</param>
        /// <param name="length">需计算长度的字符串</param>
        /// <returns>string</returns>
        public static string GetSubString(string str, int length)
        {
            string temp = str;
            int j = 0;
            int k = 0;
            for (int i = 0; i < temp.Length; i++)
            {
                if (Regex.IsMatch(temp.Substring(i, 1), @"[\u4e00-\u9fa5]+"))
                {
                    j += 2;
                }
                else
                {
                    j += 1;
                }
                if (j <= length)
                {
                    k += 1;
                }
                if (j > length)
                {
                    return temp.Substring(0, k) + "..";
                }
            }
            return temp;
        }
//csharp/8582