Question

考虑以下VB代码：

Public Async Function someFunction(ByVal url As String, Optional ByVal methodPost As Boolean = False, Optional ByVal postContent As HttpContent = Nothing) As Threading.Tasks.Task(Of String)
    Using client = New HttpClient
        client.DefaultRequestHeaders.Authorization = makeAuthenticationHeader()

        If methodPost Then
            client.DefaultRequestHeaders.Accept.Add(New MediaTypeWithQualityHeaderValue("application/json"))

            Dim Response = Await client.PostAsync(url, postContent)

            Dim content As String = Await Response.Content.ReadAsStringAsync
            Return content
        Else
            Return Await client.GetStringAsync(url)
        End If
    End Using
End Function

我想将请求内容类型设置为application/json以及将响应内容类型设置为application/json。

如果我添加以下代码行： client.DefaultRequestHeaders.Add("content-type", "application/json")然后系统抛出异常Misused header name. Make sure request headers are used with HttpRequestMessage, response headers with HttpResponseMessage, and content headers with HttpContent objects.。

我已经在google上搜索了将请求标头设置为JSON的方法。使用fiddler（在服务器上）我可以看到请求是以普通/文本形式发送的。

POST **URL REMOVED FOR SAFETY REASONS** HTTP/1.1
Authorization: Basic **HASHED AUTH DETAILS - REMOVED FOR SAFETY REASONS**
Accept: application/json
Content-Type: text/plain; charset=utf-8
Host: **HOST REMOVED FOR SAFETY REASONS**
Content-Length: 1532
Expect: 100-continue
Connection: Keep-Alive

Content-Type: text/plain; charset=utf-8这就是我遇到问题的地方。这需要设置为JSON的内容类型，因为请求的主体是JSON。如何在vb.net代码中将此content-type设置为JSON。

Answer 1

我找到了一个解决方案，我不知道它是否是正确的解决方案，或者是否有更好的解决方案。

基本上，您需要在发送的实际内容上设置content-type标头，而不是在HTTP客户端上。

因此，基本上将content.Headers.ContentType = New MediaTypeWithQualityHeaderValue("application/json")添加到代码中也应将 REQUEST的内容类型设置为JSON。

Public Async Function someDifferentFunction() As Threading.Tasks.Task(Of String)
    Dim url As String = "http://xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
    Dim content As HttpContent = New StringContent(txtRequestBody.Text)
    content.Headers.ContentType = New MediaTypeWithQualityHeaderValue("application/json")
    Return Await someFunction(url, True, content)
End Function

设置REQUEST头Http Client vb.net

1 个答案: