不加入Web參考，使用 HttpWebRequest+HttpWebResponse 取得WebService的回傳值

2008-09-13

15745
0
VB.NET
2008-09-19

摘要:不加入Web參考，使用 HttpWebRequest+HttpWebResponse 取得WebService的回傳值

很多人都會使用Web參考加入WebService，可是當主管說不希望這麼做的時後怎麼辦

這時就要利用 System.Net 的類別

以下是實做過程

寫一個簡單的WebService：

     Public Function HelloWorld() Function HelloWorld(ByVal recStr As String) As String 
'經過編碼，所以接回來要解碼        
        Dim tmp As String = Server.UrlDecode(recStr) 
         Return "這是從WebService傳回來的字串：" & tmp 
     End Function

首先參考WebService網頁所提供的範例(原則上是照抄)

接下來開一個簡單的WindowForm專案，放入一個 BUTTON，跟 TEXTBOX

記得要先加入參考：(手動加入)

Imports System.Web 
Imports System.Xml

Button的程式：

         Dim req As HttpWebRequest 
         Dim reps As HttpWebResponse 
         Dim url As String = "" 
         Dim reqStr As String = "" 
  
         Try 
             'WebService的網址 
             url = "http://localhost/myWeb/PrintStr.asmx " 
             req = CType(System.Net.HttpWebRequest.Create(url), HttpWebRequest) 
             req.ContentType = "application/soap+xml; charset=utf-8" 
             req.Method = "POST" 
             reqStr = "<?xml version=""1.0"" encoding=""utf-8""?>" 
             reqStr &= "<soap12:Envelope xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:soap12=""http://www.w3.org/2003/05/soap-envelope"">" 
             reqStr &= "<soap12:Body>" 
             '方法名稱  
             reqStr &= "<HelloWorld xmlns=""http://tempuri.org/"">" 
             '重點：參數名稱跟傳入的值, 如果有特殊字最好要編碼 
             reqStr &= "<recStr>" & HttpUtility.UrlEncode(Me.txtMsg.Text) & "</recStr>" 
             reqStr &= "</HelloWorld>" 
             reqStr &= "</soap12:Body>" 
             reqStr &= "</soap12:Envelope>" 
             '串出來的字串長度 
             req.ContentLength = reqStr.Length 
             '寫入資料流 
             Dim sw As New IO.StreamWriter(req.GetRequestStream, System.Text.Encoding.Default) 
             sw.Write(reqStr) 
             sw.Close() 
             reps = CType(req.GetResponse, HttpWebResponse) 
             '取回資料流 
             Dim sr As New IO.StreamReader(reps.GetResponseStream) 
             '宣告一個xml文件載入回傳的字串 ，回傳的資料會是一份xml文件
             Dim xmlDoc As New XmlDocument 
             xmlDoc.Load(sr) 
             '取得第一個節點的innerText 
             Me.TextBox1.Text = xmlDoc.ChildNodes(1).FirstChild.InnerText 
             sr.Close() 
         Catch ex As Exception 
             MsgBox(ex.Message.ToString()) 
        End Try 
      End Sub

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