通过 vb.net 使用 httpost json 字符串时遇到问题

Question

这是我用来以帖子形式发送到指定 URL 的代码。

Dim url = "http://www.abc.com/new/process"

Dim data As String = nvc.ToString
Dim postAddress = New Uri(Url)

Dim request = DirectCast(WebRequest.Create(postAddress), HttpWebRequest)
request.Method = "POST"
request.ContentType = "application/json"
Dim postByteData As Byte() = UTF8Encoding.UTF8.GetBytes(data)
request.ContentLength = postByteData.Length

Using postStream As Stream = request.GetRequestStream()
    postStream.Write(postByteData, 0, postByteData.Length)
End Using

Using resp = TryCast(request.GetResponse(), HttpWebResponse)
    Dim reader = New StreamReader(resp.GetResponseStream())
    result.Response = reader.ReadToEnd()
End Using

现在的问题是我在这里没有得到任何异常，但是我应该在发布后得到的响应（成功或错误）并没有结束。网址没问题，我查了一下。我发送的方式正确吗？

Answer 1

我认为问题在于 StreamReader 上的 ReadToEnd 方法内部使用 Length 属性。如果服务器未在 http 标头中发送长度，则该值为 null。尝试使用内存流和缓冲区：

    Dim url = "http://my.posturl.com"

    Dim data As String = nvc.ToString()
    Dim postAddress = New Uri(url)

    Dim request As HttpWebRequest = WebRequest.Create(postAddress)
    request.Method = "POST"
    request.ContentType = "application/json"
    Dim postByteData As Byte() = UTF8Encoding.UTF8.GetBytes(data)
    request.ContentLength = postByteData.Length

    Using postStream As Stream = request.GetRequestStream()
        postStream.Write(postByteData, 0, postByteData.Length)
    End Using

    Using resp = TryCast(request.GetResponse(), HttpWebResponse)
        Dim b As Byte() = Nothing
        Using stream As Stream = resp.GetResponseStream()
            Using ms As New MemoryStream()
                Dim count As Integer = 0
                Do
                    Dim buf As Byte() = New Byte(1023) {}
                    count = stream.Read(buf, 0, 1024)
                    ms.Write(buf, 0, count)
                Loop While stream.CanRead AndAlso count > 0
                b = ms.ToArray()
            End Using
        End Using
        Console.WriteLine("Response: " + Encoding.UTF8.GetString(b))
        Console.ReadLine()
    End Using