ASP. NET submit Form Post mode code

The following code is the code below my post button, which has some parameters and return data for my actual project, for reference only.

if (request.querystring["po"]! = "")
{
Strpo = request.querystring["Po"]. ToString ();
}
String url = HttpContext.Current.Request.Url.AbsoluteUri.ToString (). Replace ("popage.aspx?po=" + strpo.tostring () + "", "popage.aspx?po=" + strpo.tostring () + "");
Server.Transfer (URL);
Cookiecontainer Mycookiecontainer = new Cookiecontainer ();
HttpWebRequest request = webrequest.create (URL) as HttpWebRequest;
Request. Cookiecontainer = Mycookiecontainer;
Request. Method = "GET";
Request. KeepAlive = false;

HttpWebResponse response = Request. GetResponse () as HttpWebResponse;

System.IO.Stream Responsestream = Response. GetResponseStream ();
System.IO.StreamReader reader = new System.IO.StreamReader (Responsestream, Encoding.UTF8);
String srcstring = reader. ReadToEnd ();

Get the page ViewState
String viewstateflag = "id=\" __viewstate\ "value=\" ";
int i = Srcstring.indexof (viewstateflag) + viewstateflag.length;
Int J = srcstring.indexof ("\" ", I);
String viewState = Srcstring.substring (i, j-i);

Get page Eventvalidation
String eventvalidationflag = "id=\" __eventvalidation\ "value=\" ";
i = Srcstring.indexof (eventvalidationflag) + eventvalidationflag.length;
j = srcstring.indexof ("\" ", I);
String eventvalidation = Srcstring.substring (i, j-i);

String Submitbutton = "Btnsubmit";

//Form infromation
String strversion = MaxVersion (Strpo);
String strponum = Strpo;
String strpotype = "ZN B ";
String strchangdate = DateTime.Now.ToString ("Yyyy-mm-dd");
String strsupplier = DpList1.SelectedValue.ToString ();
String strhopedate = TbjhDate.Text.ToString ();
String strqty = (this.) Page.findcontrol ("TB" + "1" + "2") as TextBox). Text.tostring ();
//Convert the text into the URL encoding string
ViewState = System.Web.HttpUtility.UrlEncode (viewState);
Eve Ntvalidation = System.Web.HttpUtility.UrlEncode (eventvalidation);
Submitbutton = System.Web.HttpUtility.UrlEncode (Submitbutton);

Concat the string data which would be submit
String formatString =
"Po_version={0}&po_num={1}&loginbutton={2}&po_type={3}&change_date={4}&supplier_name={5} &delivery_date={6}&buttons_lable={7}&__viewstate={8}&__eventvalidation={9} ";
String poststring =
String. Format (formatString, Strversion, Strpo, Submitbutton, Strpotype, Strchangdate, Strsupplier, Strhopedate, Strqty, ViewState, eventvalidation);

Convert the submit string data into the byte array
byte[] PostData = Encoding.ASCII.GetBytes (poststring);

Set the request parameters
Request = WebRequest.Create (URL) as HttpWebRequest;
Request. Method = "POST";
Request. Referer = URL;
Request. KeepAlive = false;
Request. useragent = "mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; trident/4.0; SLCC2;. NET CLR 2.0.50727;. NET CLR 3.5.30729;. NET CLR 3.0.30729; Media Center PC 6.0; infopath.2; CIBA) ";
Request. ContentType = "application/x-www-form-urlencoded";
Request. Cookiecontainer = Mycookiecontainer;
System.Net.Cookie ck = new System.Net.Cookie ("TestCookie1", "Value of Test Cookie");
Ck. Domain = Request. Requesturi.host;
Request. Cookiecontainer.add (CK);
Request. Cookiecontainer.add (response. Cookies);

Request. ContentLength = Postdata.length;

String strSQL = String. Format ("INSERT INTO Dbo.po_podetail (po_version,po_num,po_type,change_date,supplier_name,delivery_date,buttons_ lable) VALUES (' {0} ', ' {1} ', ' {2} ', ' {3} ', ' {4} ', ' {5} ', ' {6} ') ", Strversion, Strpo, Strpotype, Strchangdate, Strsupplier, Strhopedate, Strqty);
Strcon. ExecuteSQL (strSQL);

Submit the request data
System.IO.Stream outputstream = Request. GetRequestStream ();
Request. AllowAutoRedirect = true;
Outputstream.write (postdata, 0, postdata.length);
Outputstream.close ();

Get The return Data
Response = Request. GetResponse () as HttpWebResponse;
Responsestream = Response. GetResponseStream ();
reader = new System.IO.StreamReader (Responsestream, Encoding.UTF8);
srcstring = reader. ReadToEnd ();
Response.Write (srcstring);
Response.End ();