.NET Framework 4 VB.Net調用API

Question

我正在「舊」VB.Net應用程序中工作。我希望打電話給API，檢查我是否得到了404，解析JSON結果以及您可以使用API​​調用執行的所有其他常見事情。

這樣做的最乾淨的方法是什麼？我以爲我可以使用HttpClient班，但我顯然不能！ VS 2017不會讓我選擇將System.Net.Http作爲導入。

CODE

現在我這樣做，這似乎亂了。

Public Function GetUserInfo(ByVal authTokenBytes As Byte()) As WebPayWS.GetUserInfoResult 
    Dim token As New token 
    token.token1 = authTokenBytes 
    Dim userInformation As GetUserInfoResult = _myService.GetUserInfo(token) 
    If AccountExists(userInformation.accountno) Then 
    Dim response As String = GetAccountInfoFromApi(userInformation.accountno) 
    End If 
    Return userInformation 
End Function 

Private Function GetAccountInfoFromApi(accountno As String) As String 
    Dim accountInformationUrl As String = "URL" 
    Dim webClient As WebClient = New WebClient() 
    Return webClient.DownloadString(New Uri(accountInformationUrl)) 
End Function 

我堅持與WebClient？如果是，我如何使用WebClient檢查404？

Answer 1

您可以在異常與Web客戶端check this out

Private Function GetAccountInfoFromApi(accountno As String) As String 
Dim accountInformationUrl As String = "URL" 
Dim webClient As WebClient = New WebClient() 
'Return webClient.DownloadString(New Uri(accountInformationUrl)) 
Dim retString As String 

Try 
    retString = webClient.DownloadString(New Uri(accountInformationUrl)) 

    Catch ex As WebException 
    If ex.Status = WebExceptionStatus.ProtocolError AndAlso ex.Response IsNot Nothing Then 
     Dim resp = DirectCast(ex.Response, HttpWebResponse) 
     If resp.StatusCode = HttpStatusCode.NotFound Then 
      ' HTTP 404 
      'other steps you want here 
     End If 
    End If 
    'throw any other exception - this should not occur 
    Throw 
End Try 
Return retString 

End Function 

Answer 2

包裝它加入第一

• 參考右鍵單擊項目
• 添加...
  • 參考。 ..
• 瀏覽
• C：\ Program Files文件（x86）的\微軟ASP.NET \ ASP.NET MVC 4 \組件\ System.Net.Http.dll
• 好

現在，你可以導入

Imports System.Net.Http 

您還可以使用的NuGet，看到https://stackoverflow.com/a/13668810/832052