使用 BeginGetRequestStream 方法对流实例发出异步请求

using System;
using System.Net;
using System.IO;
using System.Text; using System.Threading;

class HttpWebRequestBeginGetRequest
{
    public static ManualResetEvent allDone = new ManualResetEvent(false);
    public static void Main()
    {
       

            // Create a new HttpWebRequest object.
            HttpWebRequest request=(HttpWebRequest) WebRequest.Create("http://www.contoso.com/example.aspx");   
   
            // Set the ContentType property.
            request.ContentType="application/x-www-form-urlencoded";
            // Set the Method property to 'POST' to post data to the URI.
            request.Method = "POST";
            // Start the asynchronous operation.   
            request.BeginGetRequestStream(new AsyncCallback(ReadCallback), request);   
           
            // Keep the main thread from continuing while the asynchronous
            // operation completes. A real world application
            // could do something useful such as updating its user interface.
            allDone.WaitOne();

            // Get the response.
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream streamResponse = response.GetResponseStream();
            StreamReader streamRead = new StreamReader(streamResponse);
            string responseString = streamRead.ReadToEnd();
            Console.WriteLine(responseString);
            // Close the stream object.
streamResponse.Close(); streamRead.Close(); // Release the HttpWebResponse.
            response.Close();
        }
   
    private static void ReadCallback(IAsyncResult asynchronousResult)
    {   
            HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
            // End the operation.
            Stream postStream = request.EndGetRequestStream(asynchronousResult);
            Console.WriteLine("Please enter the input data to be posted:");
            string postData = Console.ReadLine ();
           
            // Convert the string into a byte array.
            byte[] byteArray = Encoding.UTF8.GetBytes(postData);
            // Write to the request stream.
            postStream.Write(byteArray, 0, postData.Length); postStream.Close (); allDone.Set(); }}