IAsyncResult 接口

IAsyncResult 接口由包含可异步操作的方法的类实现。它是启动异步操作的方法的返回类型，如 FileStream.BeginRead，也是结束异步操作的方法的第三个参数的类型，如 FileStream.EndRead。当异步操作完成时，IAsyncResult 对象也将传递给由 AsyncCallback 委托调用的方法。

支持 IAsyncResult 接口的对象存储异步操作的状态信息，并提供同步对象以允许线程在操作完成时终止。

有关如何使用 IAsyncResult 接口的详细说明，请参见“使用异步方式调用同步方法”主题。


using System;
using System.Threading;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Contexts;
using System.Runtime.Remoting.Messaging;

//
// Context-Bound type with Synchronization Context Attribute
//
[Synchronization()]
public class SampleSyncronized : ContextBoundObject
{
    // A method that does some work - returns the square of the given number
    public int Square(int i)
    {
        Console.Write("SampleSyncronized.Square called.  ");
        Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode());
        return i*i;
    }
}


//
// Async delegate used to call a method with this signature asynchronously
//
public delegate int SampSyncSqrDelegate(int i);

//Main sample class
public class AsyncResultSample
{
    public static void Main()
    {
        int callParameter = 0;
        int callResult = 0;

        //Create an instance of a context-bound type SampleSynchronized
        //Because SampleSynchronized is context-bound, the object sampSyncObj 
        //is a transparent proxy
        SampleSyncronized sampSyncObj = new SampleSyncronized();


        //call the method synchronously
        Console.Write("Making a synchronous call on the object.  ");
        Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode());
        callParameter = 10;
        callResult = sampSyncObj.Square(callParameter);
        Console.WriteLine("Result of calling sampSyncObj.Square with {0} is {1}.\n\n", callParameter, callResult);


        //call the method asynchronously
        Console.Write("Making an asynchronous call on the object.  ");
        Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode());
        SampSyncSqrDelegate sampleDelegate = new SampSyncSqrDelegate(sampSyncObj.Square);
        callParameter = 17;

        IAsyncResult aResult = sampleDelegate.BeginInvoke(callParameter, null, null);

        //Wait for the call to complete
        aResult.AsyncWaitHandle.WaitOne();

        callResult = sampleDelegate.EndInvoke(aResult);
        Console.WriteLine("Result of calling sampSyncObj.Square with {0} is {1}.", callParameter, callResult);
    }
}