Question

我正在使用下面的代码从Twitter检索一些数据

        Dim FilterData = "follow=13,15"
        Dim Request As WebRequest = HttpWebRequest.Create("https://stream.twitter.com/1/statuses/filter.json")
        Request.ContentType = "application/x-www-form-urlencoded"
        Request.Method = "POST"
        Request.Credentials = New NetworkCredential("<Username>", "<Password>")
        Request.ContentLength = FilterData.Length

        Dim RequestStream = Request.GetRequestStream()
        Dim RequestWriter As New StreamWriter(RequestStream)
        RequestWriter.Write(FilterData)
        RequestWriter.Close()

        ' Get the response.
        Dim Response As WebResponse = Request.GetResponse()
        Console.Writeline("Reached")

如果我在Request.GetResponse()行上放置一个断点，那么它之前的所有内容都可以正常执行，但是下面的行永远不会被命中 - 也不是任何异常处理程序。我没有在输出窗口中看到任何第一次机会异常。

此调用是在工作线程上进行的，因此应用程序继续运行，但此工作人员不会执行任何其他操作。

有人可以指出错误吗？

Answer 1

您正在尝试访问streaming API。流API不指定Content-Length响应头。他们不断写信回应。因此，您应该使用异步API来访问它。例如，您可以使用WebClient：

class Program
{
    static void Main()
    {
        using (var client = new WebClient())
        {
            client.Credentials = new NetworkCredential("username", "password");
            client.OpenReadCompleted += (sender, e) =>
            {
                using (var reader = new StreamReader(e.Result))
                {
                    while (!reader.EndOfStream)
                    {
                        Console.WriteLine(reader.ReadLine());
                    }
                }
            };
            client.OpenReadAsync(new Uri("https://stream.twitter.com/1/statuses/filter.json?follow=12,13"));
        }
        Console.ReadLine();
    }
}

和VB.NET等价物：

Sub Main()
    Dim client = New WebClient()
    client.Credentials = New NetworkCredential("username", "password")
    AddHandler client.OpenReadCompleted, Sub(sender, e)
        Using reader = New StreamReader(e.Result)
            While Not reader.EndOfStream
                Console.WriteLine(reader.ReadLine())
            End While
        End Using
    End Sub
    client.OpenReadAsync(New Uri("https://stream.twitter.com/1/statuses/filter.json?follow=12,13"))
    Console.ReadLine()
End Sub

WebRequest.GetResponse退出方法，没有异常

1 个答案: