C#字符串的常用操作工具类代码分享

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("\"", "\\\"");
    }
}