C#事件和代理的简单示例程序

ccf19881030

发布于 2023-12-18 12:30:08

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发布于 2023-12-18 12:30:08

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C#事件和代理的简单示例程序

这个视频对于C#中事件和委托（代理）的讲解和示例讲得很清晰明了。首先创建一个EventAndDelegates的C# .Net控制台程序，然后输入对应的代码，运行。

程序代码如下：

Video实体类

Video.cs

using System;

namespace EventAndDelegates
{
    public class Video
    {
        public String Title { get; set; }
    }
}

VideoEncoder类-事件发布者

VideoEncoder.cs

using System;
using System.Threading;

namespace EventAndDelegates
{
    public class VideoEventArgs : EventArgs
    {
        public Video Video { get; set; }
    }

    public class VideoEncoder
    {
        // 1- Define a delegate
        // 2- Define an event based on that delegate
        // 3- Raise the event

        // C#中的代理delegate有些类似于C++中的函数指针
        //public delegate void VideoEncodedEventHandler(object source, VideoEventArgs e);

        //public event VideoEncodedEventHandler VideoEncoded;

        // EventHandler
        // EventHandler<TEventArgs>

        public EventHandler<VideoEventArgs> VideoEncoded;

        public void Encode(Video video)
        {
            Console.WriteLine("Encoding Video..." + video.Title);
            Thread.Sleep(3000);

            OnVideoEncoded(video);
        }

        protected virtual void OnVideoEncoded(Video video)
        {
            if (VideoEncoded != null)
            {
                VideoEncoded(this, new VideoEventArgs { Video = video });
            }
        }

    }
}

MailService类-事件订阅者

MailSerive.cs

using System;

namespace EventAndDelegates
{
    public class MailService
    {
        public void OnVideoEncoded(object source, VideoEventArgs args)
        {
            Console.WriteLine("MailService: Send an email..." + args.Video.Title);
        }

    }
}

MessageService类-事件订阅者

MessageService.cs

using System;

namespace EventAndDelegates
{
    public class MessageService
    {
        public void OnVideoEncoded(object source, VideoEventArgs e)
        {
            Console.WriteLine("MessageService: Send an text message..." + e.Video.Title);
        }
    }
}

主程序-main函数

Program.cs

using System;

namespace EventAndDelegates
{
    public class Program
    {
        static void Main(string[] args)
        {
            var video = new Video() { Title = "Video 1" };
            var videoEncoder = new VideoEncoder();  // publisher
            var mailService = new MailService();    // subscriber
            var messageService = new MessageService();

            videoEncoder.VideoEncoded += mailService.OnVideoEncoded;
            videoEncoder.VideoEncoded += messageService.OnVideoEncoded;

            videoEncoder.Encode(video);
        }
    }
}