说说C#的async和await

public class MyClass
{
    public MyClass()
    {
        DisplayValue(); //这里不会阻塞
        System.Diagnostics.Debug.WriteLine("MyClass() End.");
    }
    public Task<double> GetValueAsync(double num1, double num2)
    {
        return Task.Run(() =>
        {
            for (int i = 0; i < 1000000; i++)
            {
                num1 = num1 / num2;
            }
            return num1;
        });
    }
    public async void DisplayValue()
    {
        double result = await GetValueAsync(1234.5, 1.01);//此处会开新线程处理GetValueAsync任务，然后方法马上返回
        //这之后的所有代码都会被封装成委托，在GetValueAsync任务完成时调用
        System.Diagnostics.Debug.WriteLine("Value is : " + result);
    }
}

public void DisplayValue()
{
    System.Runtime.CompilerServices.TaskAwaiter<double> awaiter = GetValueAsync(1234.5, 1.01).GetAwaiter();
    awaiter.OnCompleted(() =>
        {
            double result = awaiter.GetResult();
            System.Diagnostics.Debug.WriteLine("Value is : " + result);
        });
} 

    public static class TaskAsyncHelper
    {
        /// <summary>
        /// 将一个方法function异步运行，在执行完毕时执行回调callback
        /// </summary>
        /// <param name="function">异步方法，该方法没有参数，返回类型必须是void</param>
        /// <param name="callback">异步方法执行完毕时执行的回调方法，该方法没有参数，返回类型必须是void</param>
        public static async void RunAsync(Action function, Action callback)
        {
            Func<System.Threading.Tasks.Task> taskFunc = () =>
            {
                return System.Threading.Tasks.Task.Run(() =>
                {
                    function();
                });
            };
            await taskFunc();
            if (callback != null)
                callback();
        }

        /// <summary>
        /// 将一个方法function异步运行，在执行完毕时执行回调callback
        /// </summary>
        /// <typeparam name="TResult">异步方法的返回类型</typeparam>
        /// <param name="function">异步方法，该方法没有参数，返回类型必须是TResult</param>
        /// <param name="callback">异步方法执行完毕时执行的回调方法，该方法参数为TResult，返回类型必须是void</param>
        public static async void RunAsync<TResult>(Func<TResult> function, Action<TResult> callback)
        {
            Func<System.Threading.Tasks.Task<TResult>> taskFunc = ()=>
                {
                    return System.Threading.Tasks.Task.Run(()=>
                        {
                            return function();
                        });
                };
            TResult rlt = await taskFunc();
            if(callback != null)
                callback(rlt);
        }
    }

http://blog.csdn.net/tianmuxia/article/details/17675681