利用C#建议的方式传递事件

如何利用EventArgs类来传递消息事件

我们看C#内部很多类型中的方法定义，都是两个参数，第一个是Object，第二个是Event，而这是C#非常建议的一种形式，利用这种形式传递事件，可以让代码看起来更规范，也比较好用。

需要注意的是：

EventArgs是基类，不能直接用，如果需要自定义事件，需要继承它然后写一个自己的事件类

用法相对简单，直接上代码。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace tests3
{
    //这里定义了一个自定义消息类
    public class CarEventArgs : EventArgs
    {
        public readonly string msg;
        public CarEventArgs(string message)
        {
            msg = message;
        }
    }

    public class Car
    {
        public int CurrentSpeed { get; set; }
        public int MaxSpeed { get; set; }
        public string PetName{ get; set; }

        private bool carIsDead;

        public Car() { MaxSpeed = 100; }
        public Car( string name, int maxSp, int currSp)
        {
            CurrentSpeed = currSp;
            MaxSpeed = maxSp;
            PetName = name;
        }

        public delegate void CarEngineHandler(object sender, CarEventArgs e);

        public event CarEngineHandler Exploded;

        public event CarEngineHandler AboutToBlow;

        public void Accelerate(int delta)
        {
            if (carIsDead)
            {
                if (Exploded != null)
                {
                    Exploded(this,new CarEventArgs("Sorry, this car is dead ..."));
                }
            }
            else
            {
                CurrentSpeed += delta;

                if (10 == (MaxSpeed - CurrentSpeed) && AboutToBlow != null)
                {
                    AboutToBlow(this,new CarEventArgs("Careful buddy! Gonna blow!"));
                }

                if (CurrentSpeed >= MaxSpeed)
                    carIsDead = true;
                else
                    Console.WriteLine("CurrentSpeed = {0}", CurrentSpeed);
            }
        }
    }
  
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("****  Delegates as event enablers ******\n");

            Car c1 = new Car("SlugBug", 100, 10);

            c1.AboutToBlow += CarIsAlmostDoomed;
            c1.AboutToBlow += CarAboutToBlow;

            Car.CarEngineHandler d = CarExploded;
            c1.Exploded += d;

            Console.WriteLine("**** Speeding up *****");

            for(int i = 0; i< 6;i ++)
            {
                c1.Accelerate(20);
            }
            Console.ReadLine();


            c1.Exploded -= d;

            Console.WriteLine("****** Speeding up*******");
            for(int i  = 0; i<6; i++)
            {
                c1.Accelerate(20);
            }

            Console.ReadLine();
        }

        public static void OnCarEngineEvent(string msg)
        {
            Console.WriteLine("\n ******** Message From Car Object *********");
            Console.WriteLine(" => {0}", msg);
            Console.WriteLine("******************\n");
        }

        public static void OnCarEngineEvent2(string msg)
        {
            Console.WriteLine("=>{0}", msg.ToUpper());

        }

        public static void CarAboutToBlow(object sender, CarEventArgs e)
        {
            Console.WriteLine("{0} says : {1}",sender,e.msg);
        }

        public static void CarIsAlmostDoomed(object sender, CarEventArgs e)
        {
            Console.WriteLine("=> Critical Message from Car: {0}",e.msg);
        }

        public static void CarExploded(object sender, CarEventArgs e)
        {
            Console.WriteLine(e.msg);
        }
    }
}

利用C#建议的方式传递事件

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