C#事件EventHandle、Event的使用

在C#绝大多数的事件开发中，优先使用.net自带的EventHandle事件来编写事件处理。可以解决绝大部分的事件操作，另外有一小部分可以使用委托，加event事件来自定义事件编写，比如在进行自定义控件的事件时使用Eventhandle在控件事件浏览器中找不到，只能使用委托加事件的方式。

EventHandle来编写事件处理的范例

参考链接地址https://docs.microsoft.com/zh-cn/dotnet/api/system.eventhandler?redirectedfrom=MSDN&view=netframework-4.8

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Counter c = new Counter(new Random().Next(10));
            c.ThresholdReached += c_ThresholdReached;

            Console.WriteLine("press 'a' key to increase total");
            while (Console.ReadKey(true).KeyChar == 'a')
            {
                Console.WriteLine("adding one");
                c.Add(1);
            }
        }

        static void c_ThresholdReached(object sender, ThresholdReachedEventArgs e)
        {
            Console.WriteLine("The threshold of {0} was reached at {1}.", e.Threshold,  e.TimeReached);
            Environment.Exit(0);
        }
    }

    class Counter
    {
        private int threshold;
        private int total;

        public Counter(int passedThreshold)
        {
            threshold = passedThreshold;
        }

        public void Add(int x)
        {
            total += x;
            if (total >= threshold)
            {
                ThresholdReachedEventArgs args = new ThresholdReachedEventArgs();
                args.Threshold = threshold;
                args.TimeReached = DateTime.Now;
                OnThresholdReached(args);
            }
        }

        protected virtual void OnThresholdReached(ThresholdReachedEventArgs e)
        {
            EventHandler<ThresholdReachedEventArgs> handler = ThresholdReached;
            if (handler != null)
            {
                handler(this, e);
            }
        }

        public event EventHandler<ThresholdReachedEventArgs> ThresholdReached;
    }

    public class ThresholdReachedEventArgs : EventArgs
    {
        public int Threshold { get; set; }
        public DateTime TimeReached { get; set; }
    }
}

使用委托加事件方式

参考链接https://docs.microsoft.com/zh-cn/previous-versions/8627sbea(v=vs.110)?redirectedfrom=MSDN

public class SampleEventArgs
    {
        public SampleEventArgs(string s) { Text = s; }
        public String Text {get; private set;} // readonly
    }
    public class Publisher
    {
        // Declare the delegate (if using non-generic pattern).
        public delegate void SampleEventHandler(object sender, SampleEventArgs e);

        // Declare the event.
        public event SampleEventHandler SampleEvent;

        // Wrap the event in a protected virtual method
        // to enable derived classes to raise the event.
        protected virtual void RaiseSampleEvent()
        {
            // Raise the event by using the () operator.
            if (SampleEvent != null)
                SampleEvent(this, new SampleEventArgs("Hello"));
        }
    }

事件传递消息也可以使用默认的Eventarg，当没有什么消息需要传递时，当有需要传递的消息时还是建议自定义一个消息类来进行传递

来源：CSDN

作者：ilovelab

链接：https://blog.csdn.net/yue1453544229/article/details/103741161

标签

event

threshold