.NET截取指定长度汉字超出部分以“...”代替

/// <summary>
/// 将指定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))
// throw new NullReferenceException("原字符串不能为空");
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;
}