Delegate的用法

一  调用多个方法

 

delegate void SampleDelegate(string content);
   
    class Program
    ...{
        static void Main(string[] args)
        ...{
            SampleDelegate d1, d2, d3, d4, d5;
            d1 = SayHello2;
            d2 = SayHi2;
            d3 = d1 + d2;
            d4 = d3 - d1;
            d5 = d1 + d1;
            Console.WriteLine("Invoking delegate d1:");
            d1("Daniel");
            Console.WriteLine();
            Console.WriteLine("Invoking delegate d2:");
            d2("Daniel");
            Console.WriteLine();
            Console.WriteLine("Invoking delegate d3:");
            d3("Daniel");
            Console.WriteLine();
            Console.WriteLine("Invoking delegate d4:");
            d4("Daniel");
            Console.WriteLine();
            Console.WriteLine("Invoking delegate d5:");
            d5("Daniel");
            Console.WriteLine();

            Console.ReadLine();
        }
        static void SayHello(string name)
        ...{
            Console.WriteLine(Thread.CurrentThread.ManagedThreadId);
            Console.WriteLine("Hello, {0}", name);
        }
        static void SayHi(string name)
        ...{
            Console.WriteLine(Thread.CurrentThread.ManagedThreadId);
            Console.WriteLine("Hi, {0}", name);
        }
        static void SayHello2(string name)
        ...{
            Thread.Sleep(1000);
            Console.WriteLine("Hello, {0}", name);
        }
        static void SayHi2(string name)
        ...{
            Thread.Sleep(1000);
            Console.WriteLine("Hi, {0}", name);
        }
    }

二 定义事件

 

 class Program
    ...{
        static void Main(string[] args)
        ...{
            Program prog = new Program();
            SayHelloHandler handler = new SayHelloHandler(SayHello);
            // 同步调用
            Console.WriteLine("synchronous invoke begin");
            Console.WriteLine(handler.Invoke("Daniel"));
            Console.WriteLine("synchronous invoke end");
            Console.WriteLine();
            // 异步调用
            Console.WriteLine("asynchronous invoke begin");
            handler.BeginInvoke("Daniel", new AsyncCallback(callback), handler);
            Console.WriteLine("asynchronous invoke end");
            Console.ReadLine();
        }
        public static string SayHello(string name)
        ...{
            Thread.Sleep(10000);
            return string.Format("Hello World, {0}!", name);
        }
        public static void callback(IAsyncResult ar)
        ...{
            SayHelloHandler handler = (SayHelloHandler)ar.AsyncState;
            Console.WriteLine(handler.EndInvoke(ar));
        }
    }
    delegate string SayHelloHandler(string name);