17委托异步调用方法

抽象出一个炒菜的类。

    //炒菜
    public class Cooking
    {
        public string Cook(string food1, string food2)
        {
            Thread.CurrentThread.Name = "王大厨";
            Console.WriteLine("厨师开始炒菜");

            for (int i = 1; i <= 2; i++)
            {
                Thread.Sleep(TimeSpan.FromSeconds(i));
                Console.WriteLine("{0}:在炒菜(时间:{1}秒)",Thread.CurrentThread.Name,i);
            }
            Console.WriteLine("好了，菜做完了");
            return food1 + food2;
        }
    }

客户端调用该类和方法，只有等炒菜线程执行完才能执行后面。

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("客人点菜了！");

            Cooking cooking = new Cooking();
            string result = cooking.Cook("鱼香", "肉丝");
            Console.WriteLine("{0}好了，请慢用。", result);

            Console.WriteLine("客人吃饭");
            Console.ReadKey();
        }
    }

 

我们想让客人在炒菜上来之前喝点水，嗑点瓜子......
那就把炒菜的事交给委托，客人就可以放心地做其它事了。 

 

  使用委托异步调用注册方法

using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication17
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("客人点菜了！");

            Cooking cooking = new Cooking();
            CookDelegate del = new CookDelegate(cooking.Cook); //给委托注册方法
            IAsyncResult asyncResult = del.BeginInvoke("西红柿", "鸡蛋", null, null);
            Console.WriteLine("客人做点其它事......");
            string result = del.EndInvoke(asyncResult);
            Console.WriteLine("{0}好了，请慢用。", result);
            Console.ReadKey();
        }
    }

    public delegate string CookDelegate(string food1, string food2);

    //炒菜
    public class Cooking
    {
        public string Cook(string food1, string food2)
        {
            Thread.CurrentThread.Name = "王大厨";
            Console.WriteLine("厨师开始炒菜");

            for (int i = 1; i <= 2; i++)
            {
                Thread.Sleep(TimeSpan.FromSeconds(i));
                Console.WriteLine("{0}:在炒菜(时间:{1}秒)",Thread.CurrentThread.Name,i);
            }
            Console.WriteLine("好了，菜做完了");
            return food1 + food2;
        }
    }
}

    

 

  委托异步调用注册方法结束后调用回调方法

using System.Runtime.Remoting.Messaging;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication17
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("客人点菜了！");

            Cooking cooking = new Cooking();
            CookDelegate del = new CookDelegate(cooking.Cook); //给委托注册方法

            string data = "希望您能喜欢";
            AsyncCallback callBack = new AsyncCallback(OnCookComplete);
            IAsyncResult asyncResult = del.BeginInvoke("西红柿", "鸡蛋", callBack, data);
            Console.WriteLine("客人做点其它事......");

            Console.ReadKey();
        }

        //回调需要执行的方法
        static void OnCookComplete(IAsyncResult asyncResult)
        {
            AsyncResult result = (AsyncResult) asyncResult;

            //从异步结果中可以拿到委托
            CookDelegate del = (CookDelegate)result.AsyncDelegate;

            //从异步结果中可以拿到BeginInvoke方法中的object参数
            string data = (string) asyncResult.AsyncState;

            string r = del.EndInvoke(asyncResult);
            Console.WriteLine("{0}好了，请慢用,{1}", r,data);
        }
    }

    public delegate string CookDelegate(string food1, string food2);

    //炒菜
    public class Cooking
    {
        public string Cook(string food1, string food2)
        {
            Thread.CurrentThread.Name = "王大厨";
            Console.WriteLine("厨师开始炒菜");

            for (int i = 1; i <= 2; i++)
            {
                Thread.Sleep(TimeSpan.FromSeconds(i));
                Console.WriteLine("{0}:在炒菜(时间:{1}秒)",Thread.CurrentThread.Name,i);
            }
            Console.WriteLine("好了，菜做完了");
            return food1 + food2;
        }
    }
}

 

 

可见：
● 当使用委托异步调用注册的方法时，不会影响到客户端，客户端程序不会等
● 当异步调用委托注册的方法时，参数不仅有方法参数，还有AsyncCallback回调参数，和object对象
● 回调方法中，可以从IAsyncResult获取方法返回值，object对象