本文发表在 rolia.net 枫下论坛I have 4 kinds of asychrous calls methods. I have tested them all.

First one

using System;

public class AsyncMain4
{
// Asynchronous method puts the thread id here.
private static int threadId;

public static void Main(string[] args)
{
// Create an instance of the test class.
AsyncDemo ad = new AsyncDemo();

// Create the delegate.
AsyncDelegate dlgt = new AsyncDelegate(ad.TestMethod);

// Initiate the asychronous call. Include an AsyncCallback
// delegate representing the callback method, and the data
// needed to call EndInvoke.
IAsyncResult ar = dlgt.BeginInvoke(3000,
out threadId,
new AsyncCallback(CallbackMethod),
dlgt );

Console.WriteLine("Press Enter to close application.");
Console.ReadLine();
}

// Callback method must have the same signature as the
// AsyncCallback delegate.
static void CallbackMethod(IAsyncResult ar)
{
// Retrieve the delegate.
AsyncDelegate dlgt = (AsyncDelegate) ar.AsyncState;

// Call EndInvoke to retrieve the results.
string ret = dlgt.EndInvoke(out threadId, ar);

Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".", threadId, ret);
}
}

Second one:
using System;
using System.Threading;

public class AsyncMain1
{
public static void Main(string[] args)
{
// The asynchronous method puts the thread id here.
int threadId;

// Create an instance of the test class.
AsyncDemo ad = new AsyncDemo();

// Create the delegate.
AsyncDelegate dlgt = new AsyncDelegate(ad.TestMethod);

// Initiate the asychronous call.
IAsyncResult ar = dlgt.BeginInvoke(3000, out threadId, null, null);

Thread.Sleep(0);
Console.WriteLine("Main thread {0} does some work.",
AppDomain.GetCurrentThreadId());

// Call EndInvoke to Wait for the asynchronous call to complete,
// and to retrieve the results.
string ret = dlgt.EndInvoke(out threadId, ar);

Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".", threadId, ret);
}
}

third one
using System;
using System.Threading;

public class AsyncMain3
{
public static void Main(string[] args)
{
// The asynchronous method puts the thread id here.
int threadId;

// Create an instance of the test class.
AsyncDemo ad = new AsyncDemo();

// Create the delegate.
AsyncDelegate dlgt = new AsyncDelegate(ad.TestMethod);

// Initiate the asychronous call.
IAsyncResult ar = dlgt.BeginInvoke(3000,
out threadId, null, null);

// Poll while simulating work.
while(ar.IsCompleted == false)
{
Thread.Sleep(10);
}

// Call EndInvoke to retrieve the results.
string ret = dlgt.EndInvoke(out threadId, ar);

Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".", threadId, ret);
}
}

fourth one:
using System;
using System.Threading;

public class AsyncMain2
{
public static void Main(string[] args)
{
// The asynchronous method puts the thread id here.
int threadId;

// Create an instance of the test class.
AsyncDemo ad = new AsyncDemo();

// Create the delegate.
AsyncDelegate dlgt = new AsyncDelegate(ad.TestMethod);

// Initiate the asychronous call.
IAsyncResult ar = dlgt.BeginInvoke(3000,
out threadId, null, null);

Thread.Sleep(0);
Console.WriteLine("Main thread {0} does some work.",
AppDomain.GetCurrentThreadId());

// Wait for the WaitHandle to become signaled.
ar.AsyncWaitHandle.WaitOne();

// Perform additional processing here.
// Call EndInvoke to retrieve the results.
string ret = dlgt.EndInvoke(out threadId, ar);

Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".", threadId, ret);
}
}更多精彩文章及讨论，请光临枫下论坛 rolia.net

using System;
using System.Threading;

public class AsyncDemo
{
// The method to be executed asynchronously.
//
public string TestMethod(int callDuration, out int threadId)
{
Console.WriteLine("Test method begins.");
Thread.Sleep(callDuration);
threadId = AppDomain.GetCurrentThreadId();
return "MyCallTime was " + callDuration.ToString();
}
}

// The delegate must have the same signature as the method
// you want to call asynchronously.
public delegate string AsyncDelegate(int callDuration, out int threadId);

public class MainClass
{
public static void Main(string[] args)
{
AsyncMain1.Main1(args);
// AsyncMain2.Main2(args);
// AsyncMain3.Main3(args);
// AsyncMain4.Main4(args);
}
}