C#异步编程由浅入深(二)之Async/Await的使用

 class Program
    {

        public static string GetMessage()
        {
            return Console.ReadLine();
        }
        public static  string TranslateMessage(string msg)
            return msg;
        public static  void DispatherMessage(string msg)
            switch (msg)
            {
                case "MOUSE_MOVE":
                    {
                        OnMOUSE_MOVE(msg);
                        break;
                    }
                case "MOUSE_DOWN":
                        OnMouse_DOWN(msg);
                default:
                    break;
            }
        public static void OnMOUSE_MOVE(string msg)
            Console.WriteLine("开始绘制鼠标形状");
        public static int Http()
            Thread.Sleep(1000);//模拟网络io延时
            return 1;
        public static void HttpAsync(Action<int> action,Action error)
            //这里我们用另一个线程来实现异步IO，由于Http方法内部是通过Sleep来模拟网络IO延时的，这里也只能通过另一个线程来实现异步IO
            //但记住，多线程是实现异步IO的一个手段而已，它不是必须的，后面会讲到如何通过一个线程来实现异步IO。
            Thread thread = new Thread(() => 
                try
                {
                    int res = Http();
                    action(res);
                }
                catch
                    error();
      
            });
            thread.Start();
        public static Task<int> HttpAsync()
            return Task.Run(() => 
                return Http();
        public static void OnMouse_DOWN(string msg)
            HttpAsync()
                .ContinueWith(t => 
                    if(t.Status == TaskStatus.Faulted)
                    }else if(t.Status == TaskStatus.RanToCompletion)
                        Console.WriteLine(1);
                        //做一些工作
                })
                    if (t.Status == TaskStatus.Faulted)
                    else if (t.Status == TaskStatus.RanToCompletion)
                        Console.WriteLine(2);
                        Console.WriteLine(3);
                });
        static void Main(string[] args)
            while (true)
                string msg = GetMessage();
                if (msg == "quit") return;
                string m = TranslateMessage(msg);
                DispatherMessage(m);
    }

//无返回值转换前
public async void Example()
{
    Task t = Task.Run(() =>
    {
        Thread.Sleep(1000);
    });
    await t;
    //做一些工作
}
//无返回值转换后
public void Example()
    t.ContinueWith(task => 
        //做一些工作

//有返回值转换前
    Task<int> t = Task.Run<int>(() =>
        return 1;
    int res = await t;
    //使用res做一些工作
//有返回值转换后
        //使用task.Result做一些工作

public static Task WorkAsync()
{
    return Task.Run(() => 
    {
        Thread.Sleep(1000);
        Console.WriteLine("Done!");
    });
}
public static async void Test()
{
    Console.WriteLine("步骤1");
    await WorkAsync();
    Console.WriteLine("步骤2");
    await WorkAsync();
    Console.WriteLine("步骤3");
}

public class TestAsyncStateMachine
    {
        public int _state = 0;
        public void Start() => MoveNext();
        public void MoveNext()
        {
            switch(_state)
            {
                case 0:
                    {
                        Goto Step0;
                    }
                case 1:
                        goto Step1;
                default:
                        Console.WriteLine("步骤3");
                        return;
            }

        Step0:
                Console.WriteLine("步骤1");
                _state = 1;
                WorkAsync().ContinueWith(t => this.MoveNext());
                return;
        Step1:
                _state = -1;
                Console.WriteLine("步骤2");
        }
    }

public static void Test()
{
    new TestAsyncStateMachine().Start();
}

public class TestAsyncStateMachine
{
    public int _state = 0;
    public void Start() => MoveNext();
    public void MoveNext()
    {
        switch(_state)
        {
            case 0:
                {
                    goto Step0;
                }
            case 1:
                    goto Step1;
            default:
                    Console.WriteLine("步骤3");
                    return;
        }
    Step0:
            Console.WriteLine("步骤1");
            _state = 1;
            TaskAwaiter taskAwaiter;
            taskAwaiter = WorkAsync().GetAwaiter();
            if (taskAwaiter.IsCompleted) goto Step1;
            taskAwaiter.OnCompleted(() => this.MoveNext());
            return;
    Step1:
            _state = -1;
            Console.WriteLine("步骤2");
            if (taskAwaiter.IsCompleted) MoveNext();
    }
}

//该类型包含GetAwaiter方法，且GetAwaiter()返回的类型包含三个必要条件
public class MyAwaiter : INotifyCompletion
{
    public void OnCompleted(Action continuation)
    {
        continuation();
    }

    public bool IsCompleted { get; }
    public void GetResult()
    
    public MyAwaiter GetAwaiter() => new MyAwaiter();
}

public static async void AwaiterTest()
{
    await new MyAwaiter();
    Console.WriteLine("Done");
}