通过httpWebRequest发布数据

Question

I need to "Post" some data to an external website using HttpWebRequest object from my application(desktop) and get a response back into my application through HttpWebResponse object. But the webpage on which im posting data have textboxes which have dynamic names.

How can I get the name of those textboxes and post data in HttpWebResquest ?

For example when I load the page the textbox name is like this U2FsdGVkX183MTQyNzE0MrhLOmUpqd3eL60xF19RmCwLlSiG5nC1H6wvtBDhjI3uM1krX_B8Fwc but when I refresh the page name change to this U2FsdGVkX182MjMwNjIzMPAtotst_q9PP9TETomXB453Mq3M3ZY5HQt70ZeyxbRb118Y8GQbgP8 .

Thanks for any suggestions.

Answer 1

var request = WebRequest.Create("http://foo");
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
using (var writer = new StreamWriter(request.GetRequestStream()))
{
    writer.Write("field=value");
}

Answer 2

You could et those names by XPath eg and user them like:

byte[]  data = new ASCIIEncoding().GetBytes("textBoxName1=blabla");
HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create("http://localhost/myservlet");
httpWebRequest.Method = "POST";
httpWebRequest.ContentType = "application/x-www-form-urlencoded";
httpWebRequest.ContentLength = data.Length;
Stream myStream = httpWebRequest.GetRequestStream();
myStream.Write(data,0,data.Length);
myStream.Close();

Answer 3

It looks like you will have to get the page with a HttpWebRequest and parse the content of the corresponding HttpWebResponse to find out the names of text boxes. Then you submit the values to the page by using another HttpWebRequest.

So basically, what you need to do is the following:

1. Issue a HttpWebRequest with GET method to the URL where the page with text boxes is located
2. Get the response stream of the HttpWebResponse
3. Parse the page contained in the response stream and get the names of text boxes. You can use HTML Agility Pack for this purpose.
4. Issue a HttpWebRequest with POST method, with content type set to "application/x-www-form-urlencoded" and key-value pairs as the content.

Answer 4

First part of your problem: Maybe the HTML tree is stable. Then you can find your way to the textbox of your interrest with XPath. Use XmlReader, XDocument and Linq to go throught it.

Answer 5

I use this function to post data. But the url you pass has to be formatted as such for example

http://example.com/login.php?userid=myid&password=somepassword

Private Function GetHtmlFromUrl(ByVal url As String) As String

        If url.ToString() = vbNullString Then
            Throw New ArgumentNullException("url", "Parameter is null or empty")
        End If
        Dim html As String = vbNullString
        Dim request As HttpWebRequest = WebRequest.Create(url)
        request.ContentType = "Content-Type: application/x-www-form-urlencoded"
        request.Method = "POST"


        Try
            Dim response As HttpWebResponse = request.GetResponse()
            Dim reader As StreamReader = New StreamReader(response.GetResponseStream())
            html = Trim$(reader.ReadToEnd)
            GetHtmlFromUrl = html
        Catch ex As WebException
            GetHtmlFromUrl = ex.Message
        End Try

    End Function