利用委托實現異步調用

剖析代碼的繼承關系: 代理Operate經歷了3次派生(綠色部分),實現了一個構造和3個虛擬函數(黃色部分).

using System;
using System.Threading;

namespace Demo
{
    public delegate int Operate(int x, int y);

    public class DelegateAsync
    {
        static int Add(int a, int b)
        {
            Console.WriteLine ("Add() invoked on thread:{0}\n", 
                Thread.CurrentThread.GetHashCode ());
            Thread.Sleep (5000);
            return a + b;
        }

        static void Main()
        {
            Console.WriteLine ("Main() invoked on thread:{0}",
                Thread.CurrentThread.GetHashCode ());
            //Add() call in Synchronouse mode
            Operate op = new Operate (Add);
            IAsyncResult result = op.BeginInvoke(10,20,null,null);
            Console.WriteLine ("Doing more in Main() exected immediately.");
            //the thread susppend on EndInvoke while 'result' is ready!
            int answer = op.EndInvoke (result);
            Console.Write("After Add() executed, result = {0}",answer);
            Console.ReadKey ();
        }
    }
}

using System;
using System.Threading;

namespace Demo
{
    public delegate int Operate(int x, int y);

    public class DelegateAsync
    {
        static int Add(int a, int b)
        {
            Console.WriteLine ("Add() invoked on thread:{0}\n", 
                Thread.CurrentThread.GetHashCode ());
            Thread.Sleep (5000);
            return a + b;
        }

        static void Main()
        {
            Console.WriteLine ("Main() invoked on thread:{0}\n",
                Thread.CurrentThread.GetHashCode ());
            //Add() call in Synchronouse mode
            Operate op = new Operate (Add);
            IAsyncResult result = op.BeginInvoke(10,20,null,null);
            //while result is not OK, do it every 500 ms.
            while (!result.AsyncWaitHandle.WaitOne(500,true)) {//result.IsCompleted
                Console.WriteLine ("Doing more work in Main().");
            }
            int answer = op.EndInvoke (result);
            Console.Write("After Add() executed, result = {0}",answer);
            Console.ReadKey ();
        }
    }
}

using System;
using System.Threading;

/// <summary>
/* Main() invoked on thread:1
Main() execute no need to wait any more.
Add() invoked on thread:3
AddComplete() invoked on thread:3
Your Addition is complete.
*/
/// </summary>
namespace Demo
{
    public delegate int Operate(int x, int y);

    public class DelegateAsync
    {
        static int Add(int a, int b)
        {
            Console.WriteLine ("Add() invoked on thread:{0}", 
                Thread.CurrentThread.GetHashCode ());
            Thread.Sleep (5000);
            return a + b;
        }

        static void AddComplete(IAsyncResult ia)
        {
            Console.WriteLine ("AddComplete() invoked on thread:{0}",
                Thread.CurrentThread.GetHashCode ());
            //Get Result value
            System.Runtime.Remoting.Messaging.AsyncResult ar=
                (System.Runtime.Remoting.Messaging.AsyncResult)ia;
            Operate op = (Operate)ar.AsyncDelegate;
            Console.WriteLine ("The value is {0}.", op.EndInvoke (ia));
        }

        static void Main()
        {
            Console.WriteLine ("Main() invoked on thread:{0}",
                Thread.CurrentThread.GetHashCode ());
            //Add() call in Synchronouse mode
            Operate op = new Operate (Add);
            IAsyncResult result = op.BeginInvoke (10, 20, new AsyncCallback (AddComplete), null);
            Console.WriteLine ("Main() execute no need to wait any more.");
            Console.ReadKey ();
        }
    }
}

using System;
using System.Threading;

/// <summary>
/*

Main() invoked on thread:1
Main() execute no need to wait any more.
Add() invoked on thread:3
AddComplete() invoked on thread:3
The value is 30.
The Main() thread is :1

*/
/// </summary>
namespace Demo
{
    public delegate int Operate(int x, int y);

    public class DelegateAsync
    {
        static int Add(int a, int b)
        {
            Console.WriteLine ("Add() invoked on thread:{0}", 
                Thread.CurrentThread.GetHashCode ());
            Thread.Sleep (5000);
            return a + b;
        }

        static void AddComplete(IAsyncResult ia)
        {
            Console.WriteLine ("AddComplete() invoked on thread:{0}",
                Thread.CurrentThread.GetHashCode ());
            //Get Result value
            System.Runtime.Remoting.Messaging.AsyncResult ar=
                (System.Runtime.Remoting.Messaging.AsyncResult)ia;
            Operate op = (Operate)ar.AsyncDelegate;
            Console.WriteLine ("The value is {0}.", op.EndInvoke (ia));
            Thread thread = (Thread)ia.AsyncState;
            Console.WriteLine ("The Main() thread is :{0}", thread.GetHashCode());
        }

        static void Main()
        {
            Console.WriteLine ("Main() invoked on thread:{0}",
                Thread.CurrentThread.GetHashCode ());
            //Add() call in Synchronouse mode
            Operate op = new Operate (Add);
            IAsyncResult result = op.BeginInvoke (10, 20, 
                new AsyncCallback (AddComplete),Thread.CurrentThread);
            Console.WriteLine ("Main() execute no need to wait any more.");
            Console.ReadKey ();
        }
    }
}