如何使用C#事件的笔记
Why do we use event
前边在委托中，委托的成员变量不是私有的，包括注册等还存在重复代码，代码不简洁，而使用事件，就能避免这类的问题。
How do we use event
1）在类定义中，在委托定义之后，定义事件
public event 委托名称 事件名称
2）设定对象发送事件，就不用注册函数了。具体使用和委托类似，但是代码简洁了很多。
CODE
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace test3
{
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(string msgForCaller);
public event CarEngineHandler Exploded;
public event CarEngineHandler AboutToBlow;
public void Accelerate(int delta)
{
if (carIsDead)
{
if (Exploded != null) //notice here
{
Exploded("Sorry, this car is dead ...");
}
}
else
{
CurrentSpeed += delta;
if (10 == (MaxSpeed - CurrentSpeed) && AboutToBlow != null)
{
AboutToBlow("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);
//register event dealing program
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(string msg)
{
Console.WriteLine(msg);
}
public static void CarIsAlmostDoomed(string msg)
{
Console.WriteLine("=> Critical Message from Car: {0}", msg);
}
public static void CarExploded(string msg)
{
Console.WriteLine(msg);
}
}
}