C#使用正则表达式把相对地址转化为绝对地址

public static void Main(string[] args)
{
    string minHtml = string.Empty;
    string url = @"http://www.agronet.com.cn/default.aspx";
    string preurl = url.Remove(url.IndexOf('/', 8)   1);//获取url的根目录地址
    minHtml = GetRequestString(url, 6000, 1, System.Text.Encoding.UTF8);//获取指定页面的内容
    Console.WriteLine(preurl);
    GetUrlListBHtml(minHtml,preurl);
    Console.ReadKey();
}
/// <summary>
/// 获取html内容中的相对url地址，并向相对地址添加前缀
/// </summary>
/// <param name="text">html内容</param>
/// <param name="pre">要添加的绝对地址前缀</param>
public static void GetUrlListBHtml(string text,string pre)
{
    string pat = @"(?<=href\s*=)(?:[ \s""']*)(?!#|mailto|location.|javascript|.*css|.*this\.)[^""']*(?:[ \s>""'])";
    // Compile the regular expression.
    System.Text.RegularExpressions.Regex r = new System.Text.RegularExpressions.Regex(pat, System.Text.RegularExpressions.RegexOptions.IgnoreCase);
    // Match the regular expression pattern against a text string.
    System.Text.RegularExpressions.Match m = r.Match(text);
    int matchCount = 0;
    while (m.Success)
    {
        string urlX=m.Value.Replace("\"","");//替换引号
        if (urlX.IndexOf("/") == 0)//相对地址
        {
            matchCount  ;
            Console.WriteLine("第"   matchCount "个相对地址：");
            Console.WriteLine("原地址是" urlX);
            Console.WriteLine("新的绝对地址是"   pre urlX);
            Console.WriteLine("------------------------------------");
        }
        m = m.NextMatch();
    }
}