protected string GetWebContent(string url)
    {
        Stream outstream = null;
        Stream instream = null;
        StreamReader sr = null;
        HttpWebResponse response = null;
        HttpWebRequest request = null;
        // 要注意的这是这个编码方式，还有内容的Xml内容的编码方式
        Encoding encoding = Encoding.GetEncoding("GBK");
        byte[] data = encoding.GetBytes(url);

        // 准备请求,设置参数
        request = WebRequest.Create(url) as HttpWebRequest;
        request.Method = "POST";
        //request.ContentType = "text/plain";
        request.ContentLength = data.Length;

        outstream = request.GetRequestStream();
        outstream.Write(data, 0, data.Length);
        outstream.Flush();
        outstream.Close();
        //发送请求并获取相应回应数据

        response = request.GetResponse() as HttpWebResponse;
        //直到request.GetResponse()程序才开始向目标网页发送Post请求
        instream = response.GetResponseStream();
        sr = new StreamReader(instream, encoding);
        //返回结果网页(html)代码

        string content = sr.ReadToEnd();
        return content;
    }

Post提交xml

代码

private string PostXml(string url, string strPost)
{
string result = "";

StreamWriter myWriter = null;

HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(url);
objRequest.Method = "POST";
objRequest.ContentLength = strPost.Length;
objRequest.ContentType = "text/xml";//提交xml 
//objRequest.ContentType = "application/x-www-form-urlencoded";//提交表单
try
{
myWriter = new StreamWriter(objRequest.GetRequestStream());
myWriter.Write(strPost);
}
catch (Exception e)
{
return e.Message;
}
finally
{
myWriter.Close();
}

HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();
using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()))
{
result = sr.ReadToEnd();
sr.Close();
}
return result;
}