using System;
 namespace ConsoleApplication1
 {
     class Class1
     {
         //聲明委托
         public delegate void AsyncEventHandler();

         //異步方法
         void Event1()
        {
            Console.WriteLine("Event1 Start");
            System.Threading.Thread.Sleep(4000);
            Console.WriteLine("Event1 End");
        }
        // 同步方法
        void Event2()
        {
            Console.WriteLine("Event2 Start");
            int i=1;
            while(i<1000)
            {
                i=i+1;
                Console.WriteLine("Event2 "+i.ToString());
            }
            Console.WriteLine("Event2 End");
        }
        [STAThread]
        static void Main(string[] args)
        {
            long start=0;
            long end=0;
            Class1 c = new Class1();
            Console.WriteLine("ready");
            start=DateTime.Now.Ticks;
            //實例委托
            AsyncEventHandler asy = new AsyncEventHandler(c.Event1);
            //異步調(diào)用開始，沒有回調(diào)函數(shù)和AsyncState,都為null
            IAsyncResult ia = asy.BeginInvoke(null, null);
            //同步開始，
            c.Event2();
            //異步結(jié)束，若沒有結(jié)束，一直阻塞到調(diào)用完成，在此返回該函數(shù)的return，若有返回值。

            asy.EndInvoke(ia);
            //都同步的情況。
            //c.Event1();
            //c.Event2();

            end =DateTime.Now.Ticks;
            Console.WriteLine("時間刻度差="+ Convert.ToString(end-start) );
            Console.ReadLine();
        }
    }
}

using System;
using System.Net;
using System.Threading;
using System.Text;
using System.IO;
// RequestState 類用于通過
// 異步調(diào)用傳遞數(shù)據(jù)
public class RequestState
{
    const int BUFFER_SIZE = 1024;
    public StringBuilder RequestData;
    public byte[] BufferRead;
    public HttpWebRequest Request;
    public Stream ResponseStream;
    // 創(chuàng)建適當(dāng)編碼類型的解碼器
    public Decoder StreamDecode = Encoding.UTF8.GetDecoder();
    public RequestState()
    {
        BufferRead = new byte[BUFFER_SIZE];
        RequestData = new StringBuilder("");
        Request = null;
        ResponseStream = null;
    }
}
// ClientGetAsync 發(fā)出異步請求
class ClientGetAsync
{
    public static ManualResetEvent allDone = new ManualResetEvent(false);
    const int BUFFER_SIZE = 1024;
    public static void Main(string[] args)
    {
        if (args.Length < 1)
        {
            showusage();
            return;
        }
        // 從命令行獲取 URI
        Uri HttpSite = new Uri(args[0]);
        // 創(chuàng)建請求對象
        HttpWebRequest wreq = (HttpWebRequest)WebRequest.Create(HttpSite);
        // 創(chuàng)建狀態(tài)對象
        RequestState rs = new RequestState();
        // 將請求添加到狀態(tài)，以便它可以被來回傳遞
        rs.Request = wreq;
        // 發(fā)出異步請求
        IAsyncResult r = (IAsyncResult)wreq.BeginGetResponse(new AsyncCallback(RespCallback), rs);
        // 將 ManualResetEvent 設(shè)置為 Wait，
        // 以便在調(diào)用回調(diào)前，應(yīng)用程序不退出
        allDone.WaitOne();
    }
    public static void showusage()
    {
        Console.WriteLine("嘗試獲取 (GET) 一個 URL");
        Console.WriteLine("\r\n用法：:");
        Console.WriteLine("ClientGetAsync URL");
        Console.WriteLine("示例：:");
        Console.WriteLine("ClientGetAsync http://www.microsoft.com/net/");
    }
    private static void RespCallback(IAsyncResult ar)
    {
        // 從異步結(jié)果獲取 RequestState 對象
        RequestState rs = (RequestState)ar.AsyncState;
        // 從 RequestState 獲取 HttpWebRequest
        HttpWebRequest req = rs.Request;
        // 調(diào)用 EndGetResponse 生成 HttpWebResponse 對象
        // 該對象來自上面發(fā)出的請求
        HttpWebResponse resp = (HttpWebResponse)req.EndGetResponse(ar);
        // 既然我們擁有了響應(yīng)，就該從
        // 響應(yīng)流開始讀取數(shù)據(jù)了
        Stream ResponseStream = resp.GetResponseStream();
        // 該讀取操作也使用異步完成，所以我們
        // 將要以 RequestState 存儲流
        rs.ResponseStream = ResponseStream;
        // 請注意，rs.BufferRead 被傳入到 BeginRead。
        // 這是數(shù)據(jù)將被讀入的位置。
        IAsyncResult iarRead = ResponseStream.BeginRead(rs.BufferRead, 0, BUFFER_SIZE, new AsyncCallback(ReadCallBack), rs);
    }
    private static void ReadCallBack(IAsyncResult asyncResult)
    {
        // 從 asyncresult 獲取 RequestState 對象
        RequestState rs = (RequestState)asyncResult.AsyncState;
        // 取出在 RespCallback 中設(shè)置的 ResponseStream
        Stream responseStream = rs.ResponseStream;
        // 此時 rs.BufferRead 中應(yīng)該有一些數(shù)據(jù)。
        // 讀取操作將告訴我們那里是否有數(shù)據(jù)
        int read = responseStream.EndRead(asyncResult);
        if (read > 0)
        {
            // 準(zhǔn)備 Char 數(shù)組緩沖區(qū)，用于向 Unicode 轉(zhuǎn)換
            Char[] charBuffer = new Char[BUFFER_SIZE];
            // 將字節(jié)流轉(zhuǎn)換為 Char 數(shù)組，然后轉(zhuǎn)換為字符串
            // len 顯示多少字符被轉(zhuǎn)換為 Unicode
            int len = rs.StreamDecode.GetChars(rs.BufferRead, 0, read, charBuffer, 0);
            String str = new String(charBuffer, 0, len);
            // 將最近讀取的數(shù)據(jù)追加到 RequestData stringbuilder 對象中，
            // 該對象包含在 RequestState 中
            rs.RequestData.Append(str);
            // 現(xiàn)在發(fā)出另一個異步調(diào)用，讀取更多的數(shù)據(jù)
            // 請注意，將不斷調(diào)用此過程，直到
            // responseStream.EndRead 返回 -1
            IAsyncResult ar = responseStream.BeginRead(rs.BufferRead, 0, BUFFER_SIZE, new AsyncCallback(ReadCallBack), rs);
        }
        else
        {
            if (rs.RequestData.Length > 1)
            {
                // 所有數(shù)據(jù)都已被讀取，因此將其顯示到控制臺
                string strContent;
                strContent = rs.RequestData.ToString();
                Console.WriteLine(strContent);
            }
            // 關(guān)閉響應(yīng)流
            responseStream.Close();
            // 設(shè)置 ManualResetEvent，以便主線程可以退出
            allDone.Set();
        }
        return;
    }
}