See the following for a sample which does this: http://www.codeproject.com/KB/dotnet/NET_Interact_j2EE.aspx
I have put the sample below. Sorry, I know it's big, but you never know how long links like this will stay valid.
NOTE: the first version of the question didn't say in C# .NET - it just said "in .NET". (perhaps it was tagged C# and I didn't see it) Converting from VB.NET to C# is pretty easy (though unnecessary).
'This class is representing the same functionality of xmlHTTP object in MSXML.XMLHTTP.
Imports System.Net
Imports System.Web.HttpUtility
Public Class XMLHTTP
'Makes an internet connection to specified URL
Public Overridable Sub open(ByVal bstrMethod As String, _
ByVal bstrUrl As String, Optional ByVal varAsync As _
Object = False, Optional ByVal bstrUser _
As Object = "", Optional ByVal bstrPassword As Object = "")
Try
strUrl = bstrUrl
strMethod = bstrMethod
'Checking if proxy configuration
'is required...(blnIsProxy value
'from config file)
If blnIsProxy Then
'Set the proxy object
proxyObject = WebProxy.GetDefaultProxy()
'Finding if proxy exists and if so set
'the proxy configuration parameters...
If Not (IsNothing(proxyObject.Address)) Then
uriAddress = proxyObject.Address
If Not (IsNothing(uriAddress)) Then
_ProxyName = uriAddress.Host
_ProxyPort = uriAddress.Port
End If
UpdateProxy()
End If
urlWebRequest.Proxy = proxyObject
End If
'Make the webRequest...
urlWebRequest = System.Net.HttpWebRequest.Create(strUrl)
urlWebRequest.Method = strMethod
If (strMethod = "POST") Then
setRequestHeader("Content-Type", _
"application/x-www-form-urlencoded")
End If
'Add the cookie values of jessionid of weblogic
'and PH-Session value of webseal
'for retaining the same session
urlWebRequest.Headers.Add("Cookie", str_g_cookieval)
Catch exp As Exception
SetErrStatusText("Error opening method level url connection")
End Try
End Sub
'Sends the request with post parameters...
Public Overridable Sub Send(Optional ByVal objBody As Object = "")
Try
Dim rspResult As System.Net.HttpWebResponse
Dim strmRequestStream As System.IO.Stream
Dim strmReceiveStream As System.IO.Stream
Dim encode As System.Text.Encoding
Dim sr As System.IO.StreamReader
Dim bytBytes() As Byte
Dim UrlEncoded As New System.Text.StringBuilder
Dim reserved() As Char = {ChrW(63), ChrW(61), ChrW(38)}
urlWebRequest.Expect = Nothing
If (strMethod = "POST") Then
If objBody <> Nothing Then
Dim intICounter As Integer = 0
Dim intJCounter As Integer = 0
While intICounter < objBody.Length
intJCounter = _
objBody.IndexOfAny(reserved, intICounter)
If intJCounter = -1 Then
UrlEncoded.Append(System.Web.HttpUtility.UrlEncode(objBody.Substring(intICounter, _
objBody.Length - intICounter)))
Exit While
End If
UrlEncoded.Append(System.Web.HttpUtility.UrlEncode(objBody.Substring(intICounter, _
intJCounter - intICounter)))
UrlEncoded.Append(objBody.Substring(intJCounter, 1))
intICounter = intJCounter + 1
End While
bytBytes = _
System.Text.Encoding.UTF8.GetBytes(UrlEncoded.ToString())
urlWebRequest.ContentLength = bytBytes.Length
strmRequestStream = urlWebRequest.GetRequestStream
strmRequestStream.Write(bytBytes, 0, bytBytes.Length)
strmRequestStream.Close()
Else
urlWebRequest.ContentLength = 0
End If
End If
rspResult = urlWebRequest.GetResponse()
strmReceiveStream = rspResult.GetResponseStream()
encode = System.Text.Encoding.GetEncoding("utf-8")
sr = New System.IO.StreamReader(strmReceiveStream, encode)
Dim read(256) As Char
Dim count As Integer = sr.Read(read, 0, 256)
Do While count > 0
Dim str As String = New String(read, 0, count)
strResponseText = strResponseText & str
count = sr.Read(read, 0, 256)
Loop
Catch exp As Exception
SetErrStatusText("Error while sending parameters")
WritetoLog(exp.ToString)
End Try
End Sub
'Setting header values...
Public Overridable Sub setRequestHeader(ByVal bstrHeader _
As String, ByVal bstrValue As String)
Select Case bstrHeader
Case "Referer"
urlWebRequest.Referer = bstrValue
Case "User-Agent"
urlWebRequest.UserAgent = bstrValue
Case "Content-Type"
urlWebRequest.ContentType = bstrValue
Case Else
urlWebRequest.Headers(bstrHeader) = bstrValue
End Select
End Sub
Private Function UpdateProxy()
Try
If Not (IsNothing(uriAddress)) Then
If ((Not IsNothing(_ProxyName)) And _
(_ProxyName.Length > 0) And (_ProxyPort > 0)) Then
proxyObject = New WebProxy(_ProxyName, _ProxyPort)
Dim strByPass() As String = Split(strByPassList, "|")
If strByPass.Length > 0 Then
proxyObject.BypassList = strByPass
End If
proxyObject.BypassProxyOnLocal = True
If blnNetworkCredentials Then
If strDomain <> "" Then
proxyObject.Credentials = New _
NetworkCredential(strUserName, _
strPwd, strDomain)
Else
proxyObject.Credentials = New _
NetworkCredential(strUserName, _
strPwd)
End If
End If
End If
End If
Catch exp As Exception
SetErrStatusText("Error while updating proxy configurations")
WritetoLog(exp.ToString)
End Try
End Function
'Property for setting the Responsetext
Public Overridable ReadOnly Property ResponseText() As String
Get
ResponseText = strResponseText
End Get
End Property
Private urlWebRequest As System.Net.HttpWebRequest
Private urlWebResponse As System.Net.HttpWebResponse
Private strResponseText As String
Private strUrl As String
Private strMethod As String
Private proxyObject As WebProxy
Private intCount As Integer
Private uriAddress As Uri
Private _ProxyName As String
Private _ProxyPort As Integer
End Class