将指定的字符串按指定长度进行剪切

/// <summary>
    /// 将指定的字符串按指定长度进行剪切
    /// </summary>
    /// <param name="oldStr">需要截断的字符串</param>
    /// <param name="maxLength">字符串的最大长度</param>
    /// <param name="endWith">超过长度的后缀</param>
    /// <returns>如果超过长度，返回截断后的新字符串加上后缀，否则，返回原字符串</returns>
    public static string StringTruncat(string oldStr, int maxLength, string endWith)
    {
        if (string.IsNullOrEmpty(oldStr))
            return oldStr + endWith;
        if (maxLength < 1)
            throw new Exception("返回的字符串长度必须大于0");
        if (oldStr.Length > maxLength)
        {
            string strTmp = oldStr.Substring(0, maxLength);
            if(string.IsNullOrEmpty(endWith))
                return strTmp;
            else
                return strTmp+endWith;
        }
        return oldStr;
    }