Dim encoding As New UTF8Encoding()
            Dim request As HttpWebRequest = WebRequest.Create(“你的地址”)

            request.Method = "POST"
            request.Accept = "text/html, application/xhtml+xml, */*"
            request.ContentType = "application/json"

            Dim buffer As Byte() = encoding.GetBytes(body)
            request.ContentLength = buffer.Length
            request.GetRequestStream().Write(buffer, 0, buffer.Length)
            Dim response As HttpWebResponse = request.GetResponse()

            Using sr As New StreamReader(response.GetResponseStream(), encoding.UTF8)
                Return sr.ReadToEnd()
            End Using

vb.net教程
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一、需求 : 需要根据IP地址不同返回不同的数据接口。

二、实现：新建一个类模块

Public Module HttpRequestMessageExtensions
    Private Const HttpContext As String = "MS_HttpContext"
    Private Const RemoteEndpointMessage As String = "System.ServiceModel.Channels.RemoteEndpointMessageProperty"
    Private Const OwinContext As String = "MS_OwinContext"
    <System.Runtime.CompilerServices.Extension>
    Public Function GetClientIpAddress(ByVal request As HttpRequestMessage) As String
        If request.Properties.ContainsKey(HttpContext) Then
            Dim ctx As Object = request.Properties(HttpContext)
            If ctx IsNot Nothing Then
                Return ctx.Request.UserHostAddress
            End If
        End If
        If request.Properties.ContainsKey(RemoteEndpointMessage) Then
            Dim remoteEndpoint As Object = request.Properties(RemoteEndpointMessage)
            If remoteEndpoint IsNot Nothing Then
                Return remoteEndpoint.Address
            End If
        End If
        If request.Properties.ContainsKey(OwinContext) Then
            Dim owinContext_Conflict As Object = request.Properties(OwinContext)
            If owinContext_Conflict IsNot Nothing Then
                Return owinContext_Conflict.Request.RemoteIpAddress
            End If
        End If
        Return Nothing
    End Function
End Module

三、使用

 Debug.Print（Request.GetClientIpAddress()）

以上就是WebApi 获取客户端请求的IP过程。