实现.net 4.0的异步方法

.net 4.5以上有Task.Run和Task.Delay。

.net 4.0没有可以使用以下代码实现：

class TaskEx
    {
        public static Task Run(Action action)
        {
            var tcs = new TaskCompletionSource<object>();
            new Thread(() => {
                try
                {
                    action();
                    tcs.SetResult(null);
                }
                catch (Exception ex)
                {
                    tcs.SetException(ex);
                }
            }){ IsBackground = true }.Start();
            return tcs.Task;
        }
        public static Task<TResult> Run<TResult>(Func<TResult> function)
        {
            var tcs = new TaskCompletionSource<TResult>();
            new Thread(() =>
            {
                try
                {
                    tcs.SetResult(function());
                }
                catch (Exception ex)
                {
                    tcs.SetException(ex);
                }
            })
            { IsBackground = true }.Start();
            return tcs.Task;
        }
        public static Task Delay(int milliseconds)
        {
            var tcs = new TaskCompletionSource<object>();
            var timer = new System.Timers.Timer(milliseconds) { AutoReset = false };
            timer.Elapsed += delegate { timer.Dispose();tcs.SetResult(null); };
            timer.Start();
            return tcs.Task;
        }
    }
}

使用方法：

TaskEx.Run(() =>
            {
                Thread.Sleep(5000);
                Console.WriteLine("Just For Test.");
            });

            //Task.Run<TResult>(Func<TResult> function)方法
            string result = TaskEx.Run(() =>
            {
                Thread.Sleep(5000);
                return "Just For Test.";
            }).Result;
            Console.WriteLine(result);

            //Task.Delay(int milliSeconds)方法
            TaskEx.Delay(5000).Wait();