bi shang的所有汉字:如何在一段html代码中获取一个图片路径，用asp.net+c#写

/// <summary>
/// 从指定html中获取一个指定名称的图片路径
/// </summary>
/// <param name="StrHtml">html</param>
/// <param name="StrImgName">imgname</param>
public static string getImgPath(string strHtml,string strImgName)
{
string[] tmp1=new string[2];
string[] tmp2;
string str;
tmp1=strHtml.Replace(strImgName,"|").Split(new char[] {'|'});
if(2==tmp1.Length)
{
tmp2=tmp1[0].Split(new char[] {'<'});
str=tmp2[tmp2.Length-1];
tmp2=null;
tmp2=str.ToUpper().Replace("SRC","|").Split(new char[] {'|'});
str=tmp2[tmp2.Length-1];
str=str.Replace("=","");
str=str.Replace("\'","");
str=str.Replace("\"","");
///////////////////////////
str+=strImgName;
str=str.Trim();
////判断是否为网络地址
if(-1==str.ToLower().IndexOf("http://"))
{
if(str.Substring(0,1).Equals("/"))
{
str="http://"+System.Web.HttpContext.Current.Request.ServerVariables.Get("HTTP_HOST")+str;
}
else
str="http://"+System.Web.HttpContext.Current.Request.ServerVariables.Get("HTTP_HOST")+"/"+str;
}

tmp1=null;
tmp2=null;
return str;
}
else
{
tmp1=null;
tmp2=null;
return null;
}
}