ASP.NET特殊字符过滤函数

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

/// <summary>
/// 对字符串进行检查和替换其中的特殊字符
/// </summary>
/// <param name="strHtml"></param>
/// <returns></returns>
public static string HtmlToTxt(string strHtml)
{
string[] aryReg ={
@"<script[^>]*?>.*?</script>",
@"<(///s*)?!?((/w+:)?/w+)(/w+(/s*=?/s*(([""'])(|[^/7])*?/7|/w+)|.{0})|/s)*?(///s]//[""'tbnr]|[^/7])*?/7|/w+)|.{0})|/s)*?(///s*)?>",
@"([/r/n])[/s]+",
@"&(quot|#34);",
@"&(amp|#38);",
@"&(lt|#60);",
@"&(gt|#62);",
@"&(nbsp|#160);",
@"&(iexcl|#161);",
@"&(cent|#162);",
@"&(pound|#163);",
@"&(copy|#169);",
@"&#(/d+);",
@"-->",
@"<!--.*/n"
};

string newReg = aryReg[0];
string strOutput = strHtml;
for (int i = 0; i < aryReg.Length; i++)
{
Regex regex = new Regex(aryReg[i], RegexOptions.IgnoreCase);
strOutput = regex.Replace(strOutput, string.Empty);
}

strOutput.Replace("<", "");
strOutput.Replace(">", "");
strOutput.Replace("/r/n", "");

return strOutput;
}

=================另外两个函数=====================
/// <summary>
/// 替换html中的特殊字符
/// </summary>
/// <param name="theString">需要进行替换的文本。</param>
/// <returns>替换完的文本。</returns>
public string HtmlEncode(string theString)
{
theString = theString.Replace(">", ">");
theString = theString.Replace("<", "<");
theString = theString.Replace(" ", " ");
theString = theString.Replace(" ", " ");
theString = theString.Replace("/"", """);
theString = theString.Replace("/'", "'");
theString = theString.Replace("/n", "<br/> ");
return theString;
}

/// <summary>
/// 恢复html中的特殊字符
/// </summary>
/// <param name="theString">需要恢复的文本。</param>
/// <returns>恢复好的文本。</returns>
public string HtmlDiscode(string theString)
{
theString = theString.Replace(">", ">");
theString = theString.Replace("<", "<");
theString = theString.Replace(" ", " ");
theString = theString.Replace(" ", " ");
theString = theString.Replace(""", "/"");
theString = theString.Replace("'", "/'");
theString = theString.Replace("<br/> ", "/n");
return theString;
}