有用的String的扩展

1. 将字符串数组用一个符号连接起来

       public static class StringExtendsions
       {
           /// <summary>
           /// 将字符串数组用一个符号连接起来
           /// </summary>
           /// <param name="items">数组</param>
           /// <param name="joinFlag">符合，比如中文的逗号“，”</param>
           /// <returns></returns>
           public static string ToJoinString(this string[] items, string joinFlag)
           {
               if (items == null || items.Length == 0)
               {
                   return string.Empty;
               }
               System.Text.StringBuilder result = new System.Text.StringBuilder();
               int i = 1;
               int itemLength = items.Length;
               foreach (string item in items)
               {
                   result.Append(item);
                   if (!string.IsNullOrEmpty(joinFlag) && i < itemLength)
                   {
                       result.Append(joinFlag); 
                   }
                   i++;
               }
               return result.ToString();
           }
       }
   

2. 移除HTML代码，示例1：

   public static class HtmlRemoval
   {
       /// <summary>
       /// 移除 HTML 标记，
       /// 比如：HtmlRemoval.StripTagsCharArray("你好，我是<span>大侠</span>，很高兴认识大家！")
       /// 将得到 “你好，我是大侠，很高兴认识大家！”
       /// </summary>
       /// <param name="source"></param>
       /// <returns></returns>
       public static string StripTagsCharArray(string source)
       {
           char[] array = new char[source.Length];
           int arrayIndex = 0;
           bool inside = false;
           for (int i = 0; i < source.Length; i++)
           {
               char let = source[i];
               if (let == '<')
                   inside = true;
               else if (let == '>')
                   inside = false;
               else if (!inside)
               {
                   array[arrayIndex] = let;
                   arrayIndex++;
               }
           }
           return new string(array, 0, arrayIndex);
       }
   }

    

3. 移除HTML代码，示例2：

       public static class StringExtensions
       {
           /// <summary>
           /// 移除HTML代码
           /// </summary>
           /// <param name="Htmlstring">要移除的字符串</param>
           /// <returns></returns>
           public static string RemoveHTML(this string Htmlstring)
           {
               //删除脚本
               Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"<script[^>]*?>.*?</script>", "", RegexOptions.IgnoreCase);
               //删除HTML
               Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\s]+", "", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"-->", "", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"<!--.*", "", RegexOptions.IgnoreCase);
               //Htmlstring = Regex.Replace(Htmlstring,@"<A>.*</A>","");
               //Htmlstring = Regex.Replace(Htmlstring,@"<[a-zA-Z]*=\.[a-zA-Z]*\?[a-zA-Z]+=\d&\w=%[a-zA-Z]*|[A-Z0-9]","");
               Htmlstring = Regex.Replace(Htmlstring, @"&(quot|#34);", "\"", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(amp|#38);", "&", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(lt|#60);", "<", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(gt|#62);", ">", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(nbsp|#160);", " ", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(iexcl|#161);", "\xa1", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(cent|#162);", "\xa2", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(pound|#163);", "\xa3", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&(copy|#169);", "\xa9", RegexOptions.IgnoreCase);
               Htmlstring = Regex.Replace(Htmlstring, @"&#(\d+);", "", RegexOptions.IgnoreCase);
               Htmlstring.Replace("<", "");
               Htmlstring.Replace(">", "");
               Htmlstring.Replace("\r\n", "");
               //Htmlstring=HttpContext.Current.Server.HtmlEncode(Htmlstring).Trim();
               return Htmlstring;
           }
       }
   

4. 截取并省略字符串

           /// <summary>
           /// 截取并省略字符串
           /// </summary>
           /// <param name="str"></param>
           /// <param name="length">需要截取的字符长度</param>
           /// <returns></returns>
           public static string SubstringEllipsis(this string str, int length)
           {
               if (str == null)
               {
                   return null;
               }
               string result = GetSubString(str.ToString(), length);
               if (str.ToString().Length > result.Length)
               {
                   result += "...";
               }
               return result;
           }
   
           /// <summary>
           /// 获取指定字符串从 0 开始指定长度的字符。单个字符若是双字节长度算 1 若为单字节长度算 0.5。
           /// </summary>
           /// <param name="input">需要获取的字符串</param>
           /// <param name="count">需要获取的长度</param>
           /// <returns></returns>
           private static string GetSubString(string input, int count)
           {
               int outputCount = 0;
               bool appendCount = false; // 是否递增长度
               string output = "";
   
               foreach (Char c in input.ToCharArray())
               {
                   if (outputCount >= count)
                   {
                       break;
                   }
                   if (Regex.IsMatch(c.ToString(), @"[^\x00-\xff]"))
                   {
                       outputCount++; // 双字节算长度 1 
                   }
                   else
                   {
                       // 单字节算长度 0.5
                       if (!appendCount)
                       {
                           appendCount = true;
                       }
                       else
                       {
                           appendCount = false;
                           outputCount++;
                       }
                   }
                   output += c.ToString();
               }
               return output;
           }
   

5. 谢谢浏览
6. ddddd

   public static string CalculateMD5Hash(this string value)
   {
       string hash = value;
       if (value != null)
       {
           value = value.ToLower();
           MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
           byte[] data = Encoding.ASCII.GetBytes(value);
           data = md5.ComputeHash(data);
           hash = "";
           for (int i = 0; i < data.Length; i++)
           {
               hash = hash + data[i].ToString("x2");
           }
       }
       return hash;
   }