public static class ExtendedString {     /// <summary>     /// 验证字符串是否由正负号（+-）、数字、小数点构成，并且最多只有一个小数点     /// </summary>     /// <param name="str"></param>     /// <returns></returns>     public static bool IsNumeric(this string str)     {         Regex regex = new Regex(@"^[+-]?\d+[.]?\d*$");         return regex.IsMatch(str);                }     /// <summary>     /// 验证字符串是否仅由[0-9]构成     /// </summary>     /// <param name="str"></param>     /// <returns></returns>     public static bool IsNumericOnly(this string str)     {         Regex regex = new Regex("[0-9]");         return regex.IsMatch(str);     }     /// <summary>     /// 验证字符串是否由字母和数字构成     /// </summary>     /// <param name="str"></param>     /// <returns></returns>     public static bool IsNumericOrLetters(this string str)     {         Regex regex = new Regex("[a-zA-Z0-9]");         return regex.IsMatch(str);     }     /// <summary>     /// 验证是否为空字符串。若无需裁切两端空格，建议直接使用 String.IsNullOrEmpty(string)     /// </summary>     /// <param name="str"></param>     /// <returns></returns>     /// <remarks>     /// 不同于String.IsNullOrEmpty(string)，此方法会增加一步Trim操作。如 IsNullOrEmptyStr(" ") 将返回 true。     /// </remarks>     public static bool IsNullOrEmptyStr(this string str)     {         if (string.IsNullOrEmpty(str)) { return true; }         if (str.Trim().Length == 0) { return true; }         return false;     }     /// <summary>     /// 裁切字符串（中文按照两个字符计算）     /// </summary>     /// <param name="str">旧字符串</param>     /// <param name="len">新字符串长度</param>     /// <param name="HtmlEnable">为 false 时过滤 Html 标签后再进行裁切，反之则保留 Html 标签。</param>     /// <remarks>     /// <para>注意：<ol>     /// <li>若字符串被截断则会在末尾追加“...”，反之则直接返回原始字符串。</li>     /// <li>参数 <paramref name="HtmlEnable"/> 为 false 时会先调用<see cref="uoLib.Common.Functions.HtmlFilter"/>过滤掉 Html 标签再进行裁切。</li>     /// <li>中文按照两个字符计算。若指定长度位置恰好只获取半个中文字符，则会将其补全，如下面的例子：<br/>     /// <code><![CDATA[     /// string str = "感谢使用uoLib。";     /// string A = CutStr(str,4);   // A = "感谢..."     /// string B = CutStr(str,5);   // B = "感谢使..."     /// ]]></code></li>     /// </ol>     /// </para>     /// </remarks>     public static string CutStr(this string str, int len, bool HtmlEnable)     {         if (str == null || str.Length == 0 || len <= 0) { return string.Empty; }         if (HtmlEnable == false) str = HtmlFilter(str);         int l = str.Length;         #region 计算长度         int clen = 0;//当前长度         while (clen < len && clen < l)         {             //每遇到一个中文，则将目标长度减一。             if ((int)str[clen] > 128) { len--; }             clen++;         }         #endregion         if (clen < l)         {             return str.Substring(0, clen) + "...";         }         else         {             return str;         }     }     /// <summary>     /// 裁切字符串（中文按照两个字符计算，裁切前会先过滤 Html 标签）     /// </summary>     /// <param name="str">旧字符串</param>     /// <param name="len">新字符串长度</param>     /// <remarks>     /// <para>注意：<ol>     /// <li>若字符串被截断则会在末尾追加“...”，反之则直接返回原始字符串。</li>     /// <li>中文按照两个字符计算。若指定长度位置恰好只获取半个中文字符，则会将其补全，如下面的例子：<br/>     /// <code><![CDATA[     /// string str = "感谢使用uoLib模块。";     /// string A = CutStr(str,4);   // A = "感谢..."     /// string B = CutStr(str,5);   // B = "感谢使..."     /// ]]></code></li>     /// </ol>     /// </para>     /// </remarks>     public static string CutStr(this string str, int len)     {         if (IsNullOrEmptyStr(str)) { return string.Empty; }         else         {             return CutStr(str, len, false);         }     }     /// <summary>     /// 过滤HTML标签     /// </summary>     public static string HtmlFilter(this string str)     {         if (IsNullOrEmptyStr(str)) { return string.Empty; }         else         {             Regex re = new Regex(RegexPatterns.HtmlTag, RegexOptions.IgnoreCase);             return re.Replace(str, "");         }     }     /// <summary>     /// 获取字符串长度。与string.Length不同的是，该方法将中文作 2 个字符计算。     /// </summary>     /// <param name="str">目标字符串</param>     /// <returns></returns>     public static int GetLength(this string str)     {         if (str == null || str.Length == 0) { return 0; }         int l = str.Length;         int realLen = l;         #region 计算长度         int clen = 0;//当前长度         while (clen < l)         {             //每遇到一个中文，则将实际长度加一。             if ((int)str[clen] > 128) { realLen++; }             clen++;         }         #endregion         return realLen;     }     /// <summary>     /// 将形如 10.1MB 格式对用户友好的文件大小字符串还原成真实的文件大小，单位为字节。     /// </summary>     /// <param name="formatedSize">形如 10.1MB 格式的文件大小字符串</param>     /// <remarks>     /// 参见：<see cref="uoLib.Common.Functions.FormatFileSize(long)"/>     /// </remarks>     /// <returns></returns>     public static long GetFileSizeFromString(this string formatedSize)     {         if (IsNullOrEmptyStr(formatedSize)) throw new ArgumentNullException("formatedSize");         long size;         if (long.TryParse(formatedSize, out size)) return size;         //去掉数字分隔符         formatedSize = formatedSize.Replace(",", "");         Regex re = new Regex(@"^([\d\.]+)((?:TB|GB|MB|KB|Bytes))$");         if (re.IsMatch(formatedSize))         {             MatchCollection mc = re.Matches(formatedSize);             Match m = mc[0];             double s = double.Parse(m.Groups[1].Value);             switch (m.Groups[2].Value)             {                 case "TB":                     s *= 1099511627776;                     break;                 case "GB":                     s *= 1073741824;                     break;                 case "MB":                     s *= 1048576;                     break;                 case "KB":                     s *= 1024;                     break;             }             size = (long)s;             return size;         }         throw new ArgumentException("formatedSize");     }     /// <summary>     /// 根据文件夹命名规则验证字符串是否符合文件夹格式     /// </summary>     public static bool IsFolderName(this string folderName)     {         if (IsNullOrEmptyStr(folderName)) { return false; }         else         {             // 不能以 “.” 开头             folderName = folderName.Trim().ToLower();             // “nul”、“aux”、“con”、“com1”、“lpt1”不能为文件夹/文件的名称             // 作为文件夹，只需满足名称不为这几个就行。             switch (folderName)             {                 case "nul":                 case "aux":                 case "con":                 case "com1":                 case "lpt1":                     return false;                 default:                     break;             }             Regex re = new Regex(RegexPatterns.FolderName, RegexOptions.IgnoreCase);             return re.IsMatch(folderName);         }     }     /// <summary>     /// 根据文件名命名规则验证字符串是否符合文件名格式     /// </summary>     public static bool IsFileName(this string fileName)     {         if (IsNullOrEmptyStr(fileName)) { return false; }         else         {             fileName = fileName.Trim().ToLower();             // 不能以 “.” 开头             // 作为文件名，第一个“.” 之前不能是“nul”、“aux”、“con”、“com1”、“lpt1”             if (fileName.StartsWith(".")                 || fileName.StartsWith("nul.")                 || fileName.StartsWith("aux.")                 || fileName.StartsWith("con.")                 || fileName.StartsWith("com1.")                 || fileName.StartsWith("lpt1.")                 ) return false;             Regex re = new Regex(RegexPatterns.FileName, RegexOptions.IgnoreCase);             return re.IsMatch(fileName);         }     }     /// <summary>     /// 验证是否为合法的RGB颜色字符串     /// </summary>     /// <param name="color">RGB颜色，如：#00ccff | #039 | ffffcc</param>     /// <returns></returns>     public static bool IsRGBColor(this string color)     {         if (IsNullOrEmptyStr(color)) { return false; }         else         {             Regex re = new Regex(RegexPatterns.HtmlColor, RegexOptions.IgnoreCase);             return re.IsMatch(color);         }     }     public static string GetJsSafeStr(this string str)     {         if (string.IsNullOrEmpty(str))             return string.Empty;         return str.Replace("\\", "\\\\").Replace("\"", "\\\"");     } }