VB.net web Post

VB.NET Web POST是一种用于通过HTTP协议向Web服务器发送数据的技术，特别是在ASP.NET框架中。POST方法通常用于提交表单数据、上传文件等操作，因为它的请求主体可以包含大量的信息。在VB.NET中，你可以使用`HttpWebRequest`或`.NET Core`的`HttpClient`类来实现Web POST请求：

1. 使用`HttpWebRequest`示例：

Dim url As String = "http://example.com/api"
Dim data As String = "key1=value1&key2=value2" ' 将数据编码为查询字符串或JSON

Using request As HttpWebRequest = WebRequest.Create(url)
    request.Method = "POST"
    request.ContentType = If(data.Contains("="), "application/x-www-form-urlencoded", "application/json")
    
    If data.Contains("=") Then
        Dim bytes As Byte() = Encoding.UTF8.GetBytes(data)
        request.ContentLength = bytes.Length
        Using stream As Stream = request.GetRequestStream()
            stream.Write(bytes, 0, bytes.Length)
        End Using
    Else
        request.Headers.Add("Content-Type", "application/json")
        Dim jsonBytes As Byte() = Encoding.UTF8.GetBytes(New Object With {.Data = data})
        request.ContentLength = jsonBytes.Length
        Using stream As Stream = request.GetRequestStream()
            stream.Write(jsonBytes, 0, jsonBytes.Length)
        End Using
    End If
    
    Try
        Dim response As HttpWebResponse = request.GetResponse()
        ' 处理响应...
    Catch ex As Exception
        Console.WriteLine(ex.Message)
    Finally
        request.Close()
    End Try
End Using

2. 使用`.NET Core` `HttpClient`示例：

Dim httpClient As New HttpClient()
Dim content As String = "key1=value1&key2=value2"

Dim postContent As New FormUrlEncodedContent(content.Split("&".ToCharArray()))
Dim responseAsStringAsync = await httpClient.PostAsync("http://example.com/api", postContent)

If responseAsStringAsync.IsSuccessStatusCode Then
    Dim responseString = await responseAsStringAsync.Content.ReadAsStringAsync()
    ' 处理响应...
Else
    Console.WriteLine($"请求失败，状态码: {responseAsStringAsync.StatusCode}")
End If

httpClient.Dispose()