如何从vb.net中的帖子解析xml响应

Question

I am posting to a website to get data back. The site returns it as an xml. I am able to get the data into a string. But what i really want to do is to have each item in the xml in a different string field.

Sub lookup(ByVal Source As Object, ByVal e As EventArgs)
  Dim wData As String
  wData = WRequest("http://PostToThisSite.com", "POST","str=31&Password=pn&UserID=Q&Postcode="+txtPcode.Text)       
  Response.Write(wData)
End Sub

Function WRequest(URL As String, method As String, POSTdata As String) As String
    Dim responseData As String = ""
      Try
        Dim hwrequest As Net.HttpWebRequest = Net.Webrequest.Create(URL)
        hwrequest.Accept = "*/*"
        hwrequest.AllowAutoRedirect = true
        hwrequest.UserAgent = "http_requester/0.1"
        hwrequest.Timeout = 60000
        hwrequest.Method = method
        If hwrequest.Method = "POST" Then
          hwrequest.ContentType = "application/x-www-form-urlencoded"
          Dim encoding As New Text.ASCIIEncoding() 'Use UTF8Encoding for XML requests
          Dim postByteArray() As Byte = encoding.GetBytes(POSTdata)
          hwrequest.ContentLength = postByteArray.Length
          Dim postStream As IO.Stream = hwrequest.GetRequestStream()
          postStream.Write(postByteArray, 0, postByteArray.Length)
          postStream.Close()
        End If
        Dim hwresponse As Net.HttpWebResponse = hwrequest.GetResponse()
        If hwresponse.StatusCode = Net.HttpStatusCode.OK Then
          Dim responseStream As IO.StreamReader = _
            New IO.StreamReader(hwresponse.GetResponseStream())
          responseData = responseStream.ReadToEnd()
        End If
        hwresponse.Close()
        Catch e As Exception
          responseData = "An error occurred: " & e.Message
        End Try
      Return responseData
End Function

The above code works and writes out a line...

Some Road City LU1 5QG

The Xml being returned is ..

<Address xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://site.co.uk/">
  <strOrganisation /> 
  <strProperty /> 
  <strStreet>Some Road</strStreet> 
  <strLocality /> 
  <strTown>City</strTown> 
  <strCounty /> 
  <strPostcode>LU1 5QG</strPostcode> 
  <strDPS /> 

I want to be able to split these fields and set them to different text boxes on the page...help?

Answer 1

Load the xml string into an XmlDocument and extract the values with XPath :

Dim doc = new XmlDocument()
doc.LoadXml(yourXmlString)
Dim nsm = new XmlNamespaceManager(doc.NameTable)
nsm.AddNamespace("a", "http://site.co.uk/")
txtStreet.Text = doc.SelectSingleNode("/a:Address/a:strStreet", nsm).InnerText

Here's a working snippet:

Dim doc = New XmlDocument()
doc.LoadXml("<Address xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns=""http://site.co.uk/""><strOrganisation /> <strProperty /> <strStreet>Some Road</strStreet> <strLocality /> <strTown>City</strTown> <strCounty /> <strPostcode>LU1 5QG</strPostcode><strDPS /></Address>")
Dim nsm = New XmlNamespaceManager(doc.NameTable)
nsm.AddNamespace("a", "http://site.co.uk/")
Dim streetValue = doc.SelectSingleNode("/a:Address/a:strStreet", nsm).InnerText

Some things to note:

1. For XPath lookups, if your xml has a namespace you'll need to add it to an XmlNameSpaceManager created from your XmlDocument's NameTable .
2. If you don't want to bother with that, you can walk the node collections manually via doc.ChildNodes[0].ChildNodes[0] etc.

Answer 2

Or try this, which is what I believe the author was asking.

' Use XML Reader

        Dim xmlDoc = New XmlDocument
        Dim xmlNode As Xml.XmlNode
        xmlDoc.LoadXml(strResponse)

        xmlNode = xmlDoc.SelectSingleNode("//" + "strStreet")

        If Not xmlNode Is Nothing Then
            Dim Street = xmlNode.InnerText
        End If