字符串通用代码

using System;
using System.Text;
using System.Text.RegularExpressions;

namespace My.Utils
{
 /// <summary>
 /// 字符串通用工具
 /// </summary>
 public class StringUtils
 {
  /// <summary>
  /// 随机生成字符串源
  /// </summary>
  public const string RANDOM_STRING_SOURCE = "0123456789abcdefghijklmnopqrstuvwxyz";

  public StringUtils()
  {
  }

  /// <summary>
  /// 替换字符串
  /// </summary>
  /// <param name="src">要修改的字符串</param>
  /// <param name="pattern">要匹配的正则表达式模式</param>
  /// <param name="replacement">替换字符串</param>
  /// <returns>已修改的字符串</returns>
  public static string Replace (string src, string pattern, string replacement)
  {
   return Replace(src, pattern, replacement, RegexOptions.None);
  }

  /// <summary>
  /// 替换字符串,不区分大小写
  /// </summary>
  /// <param name="src">要修改的字符串</param>
  /// <param name="pattern">要匹配的正则表达式模式</param>
  /// <param name="replacement">替换字符串</param>
  /// <returns>已修改的字符串</returns>
  public static string ReplaceIgnoreCase (string src, string pattern, string replacement)
  {
   return Replace(src, pattern, replacement, RegexOptions.IgnoreCase);
  }

  /// <summary>
  /// 替换字符串
  /// </summary>
  /// <param name="src">要修改的字符串</param>
  /// <param name="pattern">要匹配的正则表达式模式</param>
  /// <param name="replacement">替换字符串</param>
  /// <param name="options">匹配模式</param>
  /// <returns>已修改的字符串</returns>
  public static string Replace (string src, string pattern, string replacement, RegexOptions options)
  {
   Regex regex = new Regex(pattern, options|RegexOptions.Compiled);

   return regex.Replace(src, replacement);
  }

  /// <summary>
  /// 删除字符串中指定的内容
  /// </summary>
  /// <param name="src">要修改的字符串</param>
  /// <param name="pattern">要删除的正则表达式模式</param>
  /// <returns>已删除指定内容的字符串</returns>
  public static string Drop (string src, string pattern)
  {
   return Replace(src, pattern, "");
  }

  /// <summary>
  /// 删除字符串中指定的内容,不区分大小写
  /// </summary>
  /// <param name="src">要修改的字符串</param>
  /// <param name="pattern">要删除的正则表达式模式</param>
  /// <returns>已删除指定内容的字符串</returns>
  public static string DropIgnoreCase (string src, string pattern)
  {
   return ReplaceIgnoreCase(src, pattern, "");
  }

  /// <summary>
  /// 替换字符串到数据库可输入模式
  /// </summary>
  /// <param name="src">待插入数据库的字符串</param>
  /// <returns>可插入数据库的字符串</returns>
  public static string ToSQL (string src)
  {
   if (src == null)
   {
    return null;
   }
   return Replace(src, "'", "''");
  }

  /// <summary>
  /// 去掉html内容中的指定的html标签
  /// </summary>
  /// <param name="content">html内容</param>
  /// <param name="tagName">html标签</param>
  /// <returns>去掉标签的内容</returns>
  public static string DropHtmlTag (string content, string tagName)
  {
   //去掉<tagname>和</tagname>
   return DropIgnoreCase(content, "<[/]{0,1}" + tagName + "[^\\>]*\\>");
  }

  /// <summary>
  /// 去掉html内容中全部标签
  /// </summary>
  /// <param name="content">html内容</param>
  /// <returns>去掉html标签的内容</returns>
  public static string DropHtmlTag (string content)
  {
   //去掉<*>
   return Drop(content, "<[^\\>]*>");
  }

  /// <summary>
  /// 生成随机字符串
  /// </summary>
  /// <param name="num">字符串的位数</param>
  /// <returns>可插入数据库的字符串</returns>
  public static string GetRandomString (int num)
  {
   string rndStr="";
   Random rnd=new Random();
   for (int i=0;i<num;i++)
   {
    rndStr += RANDOM_STRING_SOURCE.Substring(Convert.ToInt32(Math.Round(rnd.NextDouble()*36,0)),1);
   }
   return rndStr;
  }
  /// <summary>
  /// 判断一个数据是不是数字
  /// </summary>
  /// <param name="inputData">字符串</param>
  /// <returns>结果</returns>
  public static bool IsNumeric(string inputData)
  {
   Regex _isNumber = new Regex(@"^\d+$");
   Match m = _isNumber.Match(inputData);
   return m.Success;
  }

  /// <summary>
  /// 转换html标签为web页可见内容
  /// </summary>
  /// <param name="src"></param>
  /// <returns></returns>
  public static string EscapeHtml (string src)
  {
   if (src == null)
   {
    return null;
   }
   string s = src;
   s = Replace(s, ">", "&gt;");
   s = Replace(s, "<", "&lt;");
   return s;
  }

  /// <summary>
  /// 将字符串格式化成HTML代码
  /// </summary>
  /// <param name="str">要格式化的字符串</param>
  /// <returns>格式化后的字符串</returns>
  public static String ToHtml(string str)
  {
   if (str == null || str.Equals(""))
   {
    return str;
   }
           
   StringBuilder sb= new StringBuilder(str);
   sb.Replace("&", "&amp;");
   sb.Replace("<", "&lt;");
   sb.Replace(">", "&gt;");
   sb.Replace("\r\n", "<br>");
   sb.Replace("\n", "<br>");
   sb.Replace("\t", " ");
   sb.Replace(" ", "&nbsp;");
   return sb.ToString();
  }

  /// <summary>
  /// 将HTML代码转化成文本格式
  /// </summary>
  /// <param name="str">要格式化的字符串</param>
  /// <returns>格式化后的字符串</returns>
  public static String ToTxt(String str)
  {
   if (str == null || str.Equals(""))
   {
    return str;
   }
           
   StringBuilder sb= new StringBuilder(str);
   sb.Replace("&nbsp;", " ");
   sb.Replace("<br>", "\r\n");
   sb.Replace("&lt;", "<");
   sb.Replace("&gt;", ">");
   sb.Replace("&amp;", "&");
   return sb.ToString();
  }
 }
}