以前解决gb2312/big5实时转换的做法一般是修改Response.ContentEncoding

string switchLanguage(String strLanguage){
 if(strLanguage.StartsWith("zh-cn")){
  Response.ContentEncoding=Encoding.GetEncoding(936);
  return "gb2312";
 }
 if(strLanguage.StartsWith("zh")){
  Response.ContentEncoding=Encoding.GetEncoding(950);
  return "big5";
 }
 Response.ContentEncoding=Encoding.GetEncoding(1252);
 return "iso-8859-1";
}

范例：
 switchLanguage(Request.UserLanguages[0]);
 
但有些GB2312简体字没有对应的Big5,所以需要先转换成繁体的Gb2312,再进行转换
如：“秋水无恨”的无，“中国”的国，就会显示“秋水?恨”和“中?”
等需要先转化为“秋水無恨”和“中國”，再转化为Big5。(XMW)

而filter正好帮助我们实现实时切换，主要源代码如下(_sGB和_tGB是GB2312简繁体对应的库)。(XMW)

      public override void Write(byte[] buffer, int offset, int count)
      {
         Encoding e=Encoding.GetEncoding(936);
         string str=e.GetString(buffer,offset,count);
         for(int i=0;i<str.Length;i++){
          int j=_sGB.IndexOf(str[i]);
          if(j!=-1)str=str.Replace(_sGB[j],_tGB[j]);
         }
         e=Encoding.GetEncoding(System.Web.HttpContext.Current.Response.Charset);
         _sink.Write(e.GetBytes(str), 0, e.GetByteCount(str));
      
      }
 

范例：

<%@ Page Language="C#" %>
<script runat=server>
protected void Page_Load(Object sender, EventArgs ev)
{

 Response.ContentEncoding=Encoding.GetEncoding(936);
 if(Request["e"]!=null){
  Response.Filter = new qswhFilter.g2bFilter(Response.Filter);
  if(Request["e"]=="1")Response.Charset="big5";
 }
 userName.Text="秋水无恨(qiushuiwuhen)";
}
</script>
<asp:hyperlink runat=server NavigateUrl="g2bFilter.aspx" Text="Gb2312简体" />
<asp:hyperlink runat=server NavigateUrl="g2bFilter.aspx?e=0" Text="Gb2312繁体" />
<asp:hyperlink runat=server NavigateUrl="g2bFilter.aspx?e=1" Text="Big5繁体" />
hi,你好，我是<asp:label runat=server id=userName/>,欢迎来到<%="蓝色经典blueidea"%>。(XMW)

ps.如果web.config中有
 <globalization requestEncoding="gb2312" responseEncoding="gb2312" fileEncoding="gb2312"/>
可省略
 Response.ContentEncoding=Encoding.GetEncoding(936);

cs 源代码和dll：
g2bFilter.zip
dll直接拷到应用程序的bin目录即可调用