Question

我正在进行线程化webrequests。如何将参数'index'从Start（）子句传递给GetResponseCallback（）？

两个潜艇：

Shared Sub Start(ByVal index As Integer)
    Dim request As HttpWebRequest = CType(WebRequest.Create("http://sternbud.com/login/checklogin.php"), HttpWebRequest)

    request.ContentType = "application/x-www-form-urlencoded"
    request.Method = "POST"

    Debug.Print(index & ">" & AccountArray(dictThread.Keys(index)))

    Dim result As IAsyncResult = CType(request.BeginGetRequestStream(AddressOf GetRequestStreamCallback, request), IAsyncResult)

    allDone.WaitOne()
End Sub 

Private Shared Sub GetRequestStreamCallback(ByVal asynchronousResult As IAsyncResult)
    Dim request As HttpWebRequest = CType(asynchronousResult.AsyncState, HttpWebRequest)

    Dim postStream As Stream = request.EndGetRequestStream(asynchronousResult)
    Dim postData As [String] = "myusername=" & AccountArray(AccountIndex) & "&mypassword=test"


    Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postData)

    postStream.Write(byteArray, 0, postData.Length)
    postStream.Close()

    Dim result As IAsyncResult = CType(request.BeginGetResponse(AddressOf GetResponseCallback, request), IAsyncResult)
End Sub

Answer 1

您将最后一个参数中的Object传递给BeginGetRequestStream。目前你有：

Dim result As IAsyncResult = CType(request.BeginGetRequestStream(AddressOf GetRequestStreamCallback, request), IAsyncResult)

您在result参数中传递了state，并且该值已在传递的AsyncState的{{1}}属性中设置。

如果你想传递两个值，你有一些选择：

创建一个将IAsyncResult和result值作为单独属性的新对象。
创建一个index数组，其中第一项是请求，第二项是索引。然后，您可以获取Object属性，将其置于对象数组中，并剥离项目。
从您的两个值中创建Tuple，并在AsyncState参数中传递Tuple。

我更喜欢第二种，因为它很容易，但创建state更清洁（即类型安全）并且几乎一样容易。我在https://stackoverflow.com/a/4555766/56778处有第二个方法的C＃示例。

vb.net HttpWebRequest BeginGetResponse参数

1 个答案: