利用xmlHTTP获取网页源码[ASP.NET C#]

using System.Text;
using MSXML2;
public string funGetBody(string priStrUrl,string priStrMothed)
        {
            MSXML2.XMLHTTP Retrieval=new MSXML2.XMLHTTP();
            Retrieval.open(priStrMothed,priStrUrl,false,"","");
            Retrieval.send("");
            Byte[] b = (Byte[])Retrieval.responseBody;
            string HtmlCode = System.Text.ASCIIEncoding.GetEncoding("GB2312").GetString(b, 0, b.Length);
            return HtmlCode;
        }