C#使用异步方式调用同步方法的实现方法

使用异步方式调用同步方法，在此我们使用异步编程模型（APM）实现
1、定义异步委托和测试方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;namespace ApmAsyncApp
{public delegate string TestMethodAsyncCaller(int callDuration, out int threadId);/// <summary>internal class AsyncDemo{/// 执行异步调用的方法/// </summary>/// <param name="callDuration"></param>/// <param name="threadId"></param>/// <returns></returns>public string TestMethod(int callDuration,out int threadId){Console.WriteLine("Test method begins:");Thread.Sleep(callDuration);threadId=Thread.CurrentThread.ManagedThreadId;return String.Format("Call time was {0}",callDuration);}}
}

2、使用 EndInvoke 等待异步调用

static void Main(string[] args){int threadId;//创建测试类AsyncDemo asyncDemo = new AsyncDemo();//创建委托TestMethodAsyncCaller caller = new TestMethodAsyncCaller(asyncDemo.TestMethod);//初始化异步调用IAsyncResult result = caller.BeginInvoke(3000, out threadId, null, null);Thread.Sleep(0);Console.WriteLine("Main thread {0} does some work.", Thread.CurrentThread.ManagedThreadId);//调用EndInvoke检索结果string returnValue = caller.EndInvoke(out threadId, result);Console.WriteLine("The call executed on thread {0},with return value \"{1}\".", threadId, returnValue);Console.ReadLine();}

3、使用 WaitHandle 等待异步调用

static void Main(string[] args){int threadId;//创建测试类AsyncDemo asyncDemo = new AsyncDemo();//创建委托TestMethodAsyncCaller caller = new TestMethodAsyncCaller(asyncDemo.TestMethod);//初始化异步调用IAsyncResult result = caller.BeginInvoke(3000, out threadId, null, null);Thread.Sleep(0);Console.WriteLine("Main thread {0} does some work.", Thread.CurrentThread.ManagedThreadId);//sone to do//等待信号result.AsyncWaitHandle.WaitOne();//调用EndInvoke检索结果string returnValue = caller.EndInvoke(out threadId, result);result.AsyncWaitHandle.Close();Console.WriteLine("The call executed on thread {0},with return value \"{1}\".", threadId, returnValue);Console.ReadLine();}

4、对异步调用的完成情况进行轮询

static void Main(string[] args){int threadId;//创建测试类AsyncDemo asyncDemo = new AsyncDemo();//创建委托TestMethodAsyncCaller caller = new TestMethodAsyncCaller(asyncDemo.TestMethod);//初始化异步调用IAsyncResult result = caller.BeginInvoke(3000, out threadId, null, null);Thread.Sleep(0);Console.WriteLine("Main thread {0} does some work.", Thread.CurrentThread.ManagedThreadId);// 等待完成.while (result.IsCompleted == false){Thread.Sleep(250);Console.Write(".");}//调用EndInvoke检索结果string returnValue = caller.EndInvoke(out threadId, result);Console.WriteLine("The call executed on thread {0},with return value \"{1}\".", threadId, returnValue);Console.ReadLine();}

5、异步调用完成时执行回调方法

static void Main(string[] args){int threadId = 0;//创建测试类AsyncDemo asyncDemo = new AsyncDemo();//创建委托TestMethodAsyncCaller caller = new TestMethodAsyncCaller(asyncDemo.TestMethod);//初始化异步调用IAsyncResult result = caller.BeginInvoke(3000, out threadId, new AsyncCallback(callbackMethod), "The call executed on thread {0},with return value \"{1}\".");Console.WriteLine("Main thread {0} does some work.", Thread.CurrentThread.ManagedThreadId);Thread.Sleep(5000);Console.WriteLine("The main thread ends.");Console.ReadLine();}private static void callbackMethod(IAsyncResult ar){//检索委托.AsyncResult result = (AsyncResult)ar;TestMethodAsyncCaller caller = (TestMethodAsyncCaller)result.AsyncDelegate;//格式字符串作为状态信息被传递string formatString = (string)ar.AsyncState;int threadId = 0;//调用EndInvoke检查结果.string returnValue = caller.EndInvoke(out threadId, ar);//用格式字符串格式化输出信息Console.WriteLine(formatString, threadId, returnValue);}