using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading;

using System.Threading.Tasks;

namespace await和async

{

    class Program

    {

        static void Main(string[] args)

        {

            //AwaitAsync();

            //TaskRun();

            AwaitTaskRun();

        }

        #region await和async

        private static void AwaitAsync()

        {

            Say();                             //由于Main不能使用async标记

            Console.ReadLine();

        }

        private async static void Say()

        {

            var t = TestAsync();

            Thread.Sleep();                                     //主线程在执行一些任务

            Console.WriteLine("Main Thread");                       //主线程完成标记

            Console.WriteLine(await t);                             //await 主线程等待取异步返回结果

        }

        static async Task<string> TestAsync()

        {

            return await Task.Run(() =>

            {

                Thread.Sleep();                                 //异步执行一些任务

                return "Hello World";                               //异步执行完成标记

            });

        }

        #endregion

        #region task

        public static void TaskRun()

        {

            Console.WriteLine("执行GetReturnResult方法前的时间：" + DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

            var strRes = Task.Run<string>(() => { return GetReturnResult1(); });

            Console.WriteLine("执行GetReturnResult方法后的时间：" + DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

            Console.WriteLine("我是主线程，线程ID：" + Thread.CurrentThread.ManagedThreadId);

            Console.WriteLine(strRes.Result);

            Console.WriteLine("得到结果后的时间：" + DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

            Console.ReadLine();

        }

        static string GetReturnResult1()

        {

            Console.WriteLine("我是GetReturnResult里面的线程，线程ID：" + Thread.CurrentThread.ManagedThreadId);

            Thread.Sleep();

            return "我是返回值";

        }

        #endregion

        #region AwaitTaskRun

        /*

         * await:只能标记在async方法或Task对象前面；等待异步的执行结果。

         * async：标记异步方法，里面有异步执行则异步，没有则为普通方法，只能返回void、Task、Task<T>

         */

        public static void AwaitTaskRun()

        {

            Console.WriteLine("我是主线程，线程ID：{0}", Thread.CurrentThread.ManagedThreadId);

            TestAsync1();

            Console.ReadLine();

        }

        static async void TestAsync1()

        {

            Console.WriteLine("调用GetReturnResult()之前，线程ID：{0}。当前时间：{1}", Thread.CurrentThread.ManagedThreadId, DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

            var name = GetReturnResult();

            Console.WriteLine("调用GetReturnResult()之后，线程ID：{0}。当前时间：{1}", Thread.CurrentThread.ManagedThreadId, DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

            Console.WriteLine("得到GetReturnResult()方法的结果：{0}。当前时间：{1}", await name, DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

            Console.WriteLine("最后执行，线程ID：{0}。当前时间：{1}", Thread.CurrentThread.ManagedThreadId, DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));

        }

        static async Task<string> GetReturnResult()

        {

            Console.WriteLine("执行Task.Run之前, 线程ID：{0}", Thread.CurrentThread.ManagedThreadId);

            return await Task.Run(() =>

            {

                Thread.Sleep();

                Console.WriteLine("GetReturnResult()方法里面线程ID: {0}", Thread.CurrentThread.ManagedThreadId);

                return "我是返回值";

            });

        } 

        #endregion

    }

}