异步编程测试:四种模式.

using System;

namespace AsynTest
{
    public class AsyncDemo {
        public delegate string AsyncDelegate(int callDuration,out int threadId);

        public string TestMethod(int callDuration,out int threadId) {
            Console.WriteLine("Test method begins.");
            System.Threading.Thread.Sleep(callDuration);
            threadId=AppDomain.GetCurrentThreadId();
            return "MyCallTime was "+callDuration.ToString();
        }

    }
    
    
    class Class1
    {
        //使用EndInvoke等待导步调用
        public static void test1() {
            int threadId;
            AsyncDemo ad=new AsyncDemo();
            AsynTest.AsyncDemo.AsyncDelegate dlgt=new AsynTest.AsyncDemo.AsyncDelegate(ad.TestMethod);
            IAsyncResult ar=dlgt.BeginInvoke(3000,out threadId,null,null);
            
            System.Threading.Thread.Sleep(0);                        
            Console.WriteLine("Main thread {0} does some work.",AppDomain.GetCurrentThreadId());
            string ret=dlgt.EndInvoke(out threadId,ar);
            Console.WriteLine("The call exceute on thread {0},with return value \"{1}\".",threadId,ret);
        }

        //使用 WaitHandle 等待异步调用
        public static void test2() {
            int threadId;
            AsyncDemo ad=new AsyncDemo();
            AsynTest.AsyncDemo.AsyncDelegate dlgt=new AsynTest.AsyncDemo.AsyncDelegate(ad.TestMethod);
            IAsyncResult ar=dlgt.BeginInvoke(3000,out threadId,null,null);
            //阻塞当前线程,以使异部线程开始执行,异部线程开始执行后,主线程就可以继续了.
            System.Threading.Thread.Sleep(0);
            Console.WriteLine("Main thread {0} does some work.",AppDomain.GetCurrentThreadId());
            //阻塞当前线程,直接收到信号为止
            ar.AsyncWaitHandle.WaitOne();
            string ret=dlgt.EndInvoke(out threadId,ar);
            Console.WriteLine("The call exceute on thread {0},with return value \"{1}\".",threadId,ret);
        }

        //使用 轮询 等待异步调用
        public static void test3() {
            int threadId;
            AsyncDemo ad=new AsyncDemo();
            AsynTest.AsyncDemo.AsyncDelegate dlgt=new AsynTest.AsyncDemo.AsyncDelegate(ad.TestMethod);
            IAsyncResult ar=dlgt.BeginInvoke(3000,out threadId,null,null);
            //阻塞当前线程,以使异部线程开始执行,异部线程开始执行后,主线程就可以继续了.
            System.Threading.Thread.Sleep(0);
            Console.WriteLine("Main thread {0} does some work.",AppDomain.GetCurrentThreadId());
            while(!ar.IsCompleted) {
                Console.WriteLine("Waiting");
                System.Threading.Thread.Sleep(10);
            }
            string ret=dlgt.EndInvoke(out threadId,ar);
            Console.WriteLine("The call exceute on thread {0},with return value \"{1}\".",threadId,ret);
        }

        //使用回调
        ////使用回调方式不阻塞主线程,适合不需要等待异步调用结果的情况.
        public static void test4() {
            int threadId;
            AsyncDemo ad = new AsyncDemo();
            AsynTest.AsyncDemo.AsyncDelegate dlgt = new AsynTest.AsyncDemo.AsyncDelegate(ad.TestMethod);
            IAsyncResult ar = dlgt.BeginInvoke(3000,
                out threadId, 
                new AsyncCallback(test4_forCallback),
                dlgt );
            
            Console.WriteLine("Press Enter to close application.");
            Console.ReadLine();
        }
        public static void test4_forCallback(System.IAsyncResult ar) {
            int threadId;
            AsynTest.AsyncDemo.AsyncDelegate dlgt = (AsynTest.AsyncDemo.AsyncDelegate) ar.AsyncState;
            
            string ret = dlgt.EndInvoke(out threadId, ar);

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

        }

        [STAThread]
        static void Main(string[] args)
        {
            test1();
            test2();
            test3();
            test4();
        }
    }
}