C# 从开放的 HTTP 流中读取数据

Reading data from an open HTTP stream

提问by user108687

I am trying to use the .NET WebRequest/WebResponse classes to access the Twitter streaming API here "http://stream.twitter.com/spritzer.json".

我正在尝试使用 .NET WebRequest/WebResponse 类在此处访问 Twitter 流 API "http://stream.twitter.com/spritzer.json"。

I need to be able to open the connection and read data incrementally from the open connection.

我需要能够打开连接并从打开的连接中增量读取数据。

Currently, when I call WebRequest.GetResponsemethod, it blocks until the entire response is downloaded. I know there is a BeginGetResponsemethod, but this will just do the same thing on a background thread. I need to get access to the response stream while the download is still happening. This just does not seem possible to me with these classes.

目前，当我调用WebRequest.GetResponse方法时，它会阻塞，直到下载整个响应。我知道有一种BeginGetResponse方法，但这只会在后台线程上做同样的事情。我需要在下载过程中访问响应流。对于这些课程，这对我来说似乎是不可能的。

There is a specific comment about this in the Twitter documentation:

Twitter 文档中对此有具体评论：

"Please note that some HTTP client libraries only return the response body after the connection has been closed by the server. These clients will not work for accessing the Streaming API. You must use an HTTP client that will return response data incrementally. Most robust HTTP client libraries will provide this functionality. The Apache HttpClient will handle this use case, for example."

"请注意，某些 HTTP 客户端库仅在服务器关闭连接后才返回响应正文。这些客户端将无法用于访问 Streaming API。您必须使用将增量返回响应数据的 HTTP 客户端。最健壮的 HTTP客户端库将提供此功能。例如，Apache HttpClient 将处理此用例。”

They point to the Appache HttpClient, but that doesn't help much because I need to use .NET.

他们指向 Appache HttpClient，但这并没有多大帮助，因为我需要使用 .NET。

Any ideas whether this is possible with WebRequest/WebResponse, or do I have to go for lower level networking classes? Maybe there are other libraries that will allow me to do this?

任何想法是否可以使用WebRequest/WebResponse，或者我是否必须参加较低级别的网络课程？也许还有其他图书馆可以让我这样做？

Thx Allen

艾伦

回答by flesh

Have you tried WebRequest.BeginGetRequestStream()?

你试过WebRequest.BeginGetRequestStream()吗？

Or something like this:

或者像这样：

HttpWebRequest request = (HttpWebRequest)WebRequest.Create (http://www.twitter.com );
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream()); 

string str = reader.ReadLine();
while(str != null)
{
   Console.WriteLine(str);
   str = reader.ReadLine();
}

回答by anonymous coward

Just use WebClient. It is designed for simple cases like this where you don't need the full power of WebRequest.

只需使用WebClient. 它是为这样的简单情况而设计的，在这种情况下，您不需要 WebRequest 的全部功能。

System.Net.WebClient wc = new System.Net.WebClient();
Console.WriteLine(wc.DownloadString("http://stream.twitter.com/spritzer.json"));

回答by user108687

I ended up using a TcpClient, which works fine. Would still be interested to know if this is possible with WebRequest/WebResponse though. Here is my code in case anybody is interested:

我最终使用了一个 TcpClient，它工作正常。尽管如此，仍然有兴趣知道这是否可以通过 WebRequest/WebResponse 实现。这是我的代码，以防有人感兴趣：

using (TcpClient client = new TcpClient())
{

    string requestString = "GET /spritzer.json HTTP/1.1\r\n";
    requestString += "Authorization: " + token + "\r\n";
    requestString += "Host: stream.twitter.com\r\n";
    requestString += "Connection: keep-alive\r\n";
    requestString += "\r\n";

    client.Connect("stream.twitter.com", 80);

    using (NetworkStream stream = client.GetStream())
    {
        // Send the request.
        StreamWriter writer = new StreamWriter(stream);
        writer.Write(requestString);
        writer.Flush();

        // Process the response.
        StreamReader rdr = new StreamReader(stream);

        while (!rdr.EndOfStream)
        {
            Console.WriteLine(rdr.ReadLine());
        }
    }
}

回答by Darin Dimitrov

BeginGetResponseis the method you need. It allows you to read the response stream incrementally:

BeginGetResponse是您需要的方法。它允许您以增量方式读取响应流：

class Program
{
    static void Main(string[] args)
    {
        WebRequest request = WebRequest.Create("http://stream.twitter.com/spritzer.json");
        request.Credentials = new NetworkCredential("username", "password");
        request.BeginGetResponse(ar => 
        {
            var req = (WebRequest)ar.AsyncState;
            // TODO: Add exception handling: EndGetResponse could throw
            using (var response = req.EndGetResponse(ar))
            using (var reader = new StreamReader(response.GetResponseStream()))
            {
                // This loop goes as long as twitter is streaming
                while (!reader.EndOfStream)
                {
                    Console.WriteLine(reader.ReadLine());
                }
            }
        }, request);

        // Press Enter to stop program
        Console.ReadLine();
    }
}

Or if you feel more comfortable with WebClient(I personnally prefer it over WebRequest):

或者，如果您对WebClient感觉更舒服（我个人更喜欢它而不是 WebRequest）：

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("http://stream.twitter.com/spritzer.json"));
}
Console.ReadLine();