参考了一些文章，整理了一下，大家可以直接拿去用吧，其实自从有了FreeTextBox这样的东东出现，ＵＢＢ已经渐渐淡出江湖了。
using System;
using System.Text;
using System.Text.RegularExpressions;
namespace Test.Com
{
/// <summary>
/// 功能：UBB代码
/// 作者：Rexsp
/// 日期：2004-4-6
/// </summary>
public class UBB
{
#region 构造函数
public UBB()
{
//
// TODO: 在此处添加构造函数逻辑
//
}
#endregion
#region 公共静态方法
/// <summary>
/// UBB代码处理函数
/// </summary>
/// <param name="sDetail">输入字符串</param>
/// <returns>输出字符串</returns>
public static string UBBToHTML(string sDetail)
{
Regex r;
Match m;
#region 处理空格
sDetail = sDetail.Replace(" "," ");
#endregion
#region html标记符
sDetail = sDetail.Replace("<","<");
sDetail = sDetail.Replace(">",">");
#endregion
#region 处[b][/b]标记
r = new Regex(@"(\[b\])([ \S\t]*?)(\[\/b\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<B>" + m.Groups[2].ToString() + "</B>");
}
#endregion
#region 处[i][/i]标记
r = new Regex(@"(\[i\])([ \S\t]*?)(\[\/i\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<I>" + m.Groups[2].ToString() + "</I>");
}
#endregion
#region 处[u][/u]标记
r = new Regex(@"(\[U\])([ \S\t]*?)(\[\/U\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<U>" + m.Groups[2].ToString() + "</U>");
}
#endregion
#region 处[p][/p]标记
//处[p][/p]标记
r = new Regex(@"((\r\n)*\[p\])(.*?)((\r\n)*\[\/p\])",RegexOptions.IgnoreCase|RegexOptions.Singleline);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<P class=\"pstyle\">" + m.Groups[3].ToString() + "</P>");
}
#endregion
#region 处[sup][/sup]标记
//处[sup][/sup]标记
r = new Regex(@"(\[sup\])([ \S\t]*?)(\[\/sup\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<SUP>" + m.Groups[2].ToString() + "</SUP>");
}
#endregion
#region 处[sub][/sub]标记
//处[sub][/sub]标记
r = new Regex(@"(\[sub\])([ \S\t]*?)(\[\/sub\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<SUB>" + m.Groups[2].ToString() + "</SUB>");
}
#endregion
#region 处[/url]标记
//处[url]标记
r = new Regex(@"(\[url\])([ \S\t]*?)(\[\/url\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<A href=\"" + m.Groups[2].ToString() + "\" target=\"_blank\"><IMG border=0 src=\"images/url.gif\">" +
m.Groups[2].ToString() + "</A>");
}
#endregion
#region 处[/url]标记
//处[url=xxx]标记
r = new Regex(@"(\+)])([ St]*?)([/url])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<A href="" + m.Groups[2].ToString() + "" target="_blank"><IMG border=0 src="images/url.gif">" +
m.Groups[3].ToString() + "</A>");
}
#endregion
#region 处[email][/email]标记
//处[email][/email]标记
r = new Regex(@"([email])([ St]*?)([/email])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<A href="mailto:" + m.Groups[2].ToString() + "" target="_blank"><IMG border=0 src="images/email.gif">" +
m.Groups[2].ToString() + "</A>");
}
#endregion
#region 处[email=xxx][/email]标记
//处[email=xxx][/email]标记
r = new Regex(@"([email=([ St]+)])([ St]*?)([/email])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<A href="mailto:" + m.Groups[2].ToString() + "" target="_blank"><IMG border=0 src="images/email.gif">" +
m.Groups[3].ToString() + "</A>");
}
#endregion
#region 处[/size]标记
//处[size=x]标记
r = new Regex(@"()])([ St]*?)()",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<FONT SIZE=" + m.Groups[2].ToString() + ">" +
m.Groups[3].ToString() + "</FONT>");
}
#endregion
#region 处[/color]标记
//处[color=x]标记
r = new Regex(@"(+)])([ St]*?)()",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<FONT COLOR=" + m.Groups[2].ToString() + ">" +
m.Groups[3].ToString() + "</FONT>");
}
#endregion
#region 处[/font]标记
//处[font=x]标记
r = new Regex(@"(+)])([ St]*?)()",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<FONT FACE=" + m.Groups[2].ToString() + ">" +
m.Groups[3].ToString() + "</FONT>");
}
#endregion
#region 处理图片链接
//处理图片链接
r = new Regex("[url=file://%5Bpicture//%5D(//d+?)//%5B///picture//%5D%22,RegexOptions.IgnoreCase]\[picture\](\d+?)\[\/picture\]",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<A href=\"ShowImage.aspx?Type=ALL&Action=forumImage&ImageID=" + m.Groups[1].ToString() +
"\" target=\"_blank\"><IMG border=0 Title=\"点击打开新窗口查看\" src=\"ShowImage.aspx?Action=forumImage&ImageID=" + m.Groups[1].ToString() +
"\"></A>");
}
#endregion
#region 处理[align=x][/align]
//处理[align=x][/align]
r = new Regex(@"(\[align=([\S]+)\])([ \S\t]*?)(\[\/align\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<P align=" + m.Groups[2].ToString() + ">" +
m.Groups[3].ToString() + "</P>");
}
#endregion
#region 处[H=x][/H]标记
//处[H=x][/H]标记
r = new Regex(@"(\[H=([1-6])\])([ \S\t]*?)(\[\/H\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<H" + m.Groups[2].ToString() + ">" +
m.Groups[3].ToString() + "</H" + m.Groups[2].ToString() + ">");
}
#endregion
#region 处理[list=x][*][/list]
//处理[list=x][*][/list]
r = new Regex(@"(\[list(=(A|a|I|i| ))?\]([ \S\t]*)\r\n)((\[\*\]([ \S\t]*\r\n))*?)(\[\/list\])",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
string strLI = m.Groups[5].ToString();
Regex rLI = new Regex(@"\[\*\]([ \S\t]*\r\n?)",RegexOptions.IgnoreCase);
Match mLI;
for (mLI = rLI.Match(strLI); mLI.Success; mLI = mLI.NextMatch())
{
strLI = strLI.Replace(mLI.Groups[0].ToString(),"<LI>" + mLI.Groups[1]);
}
sDetail = sDetail.Replace(m.Groups[0].ToString(),
"<UL TYPE=\"" + m.Groups[3].ToString() + "\"><B>" + m.Groups[4].ToString() + "</B>" +
strLI + "</UL>");
}
#endregion
#region 处理换行
//处理换行，在每个新行的前面添加两个全角空格
r = new Regex(@"(\r\n(( )|)+)(?<正文>\S+)",RegexOptions.IgnoreCase);
for (m = r.Match(sDetail); m.Success; m = m.NextMatch())
{
sDetail = sDetail.Replace(m.Groups[0].ToString(),"<BR>" + m.Groups["正文"].ToString());
}
//处理换行，在每个新行的前面添加两个全角空格
sDetail = sDetail.Replace("\r\n","<BR>");
#endregion
return sDetail;
}
#endregion
}
}