C#笔记⑤——委托
委托
委托（delegate）是函数指针的升级版
算法（方法）是内存中一组机器语言指令
是特殊的类类型
自定义委托（delegate）
点击查看代码
delegate double Cal(double x,double y);
class Program
{
static void Main(string[] args)
{
Cal cal=new Cal(Add);
double result=cal.Invoke(5.0,6.0);
System.Console.WriteLine(result);
Console.ReadLine();
}
public static double Add(double a,double b)
{
return a+b;
}
}
Action与Func
一般我们声明委托时，会用Action类与Func类
Func类一般用于模板方法
Func<形参类型,返回类型> x=new Func<形参类型,返回类型>(xx.yy)；
Action类一般用于回调方法（callback），一般用于无返回值的方法
Action<形参类型> x=new Action<形参类型>(xx.yy)；
ACtion x=new Action(xx.yy);
模板方法
class Program
{
static void Main(string[] args)
{
WrapFactory wrapfactory1=new WrapFactory();
FoodFactory foodFactory=new FoodFactory();
Box box1=new Box();
Box box2=new Box();
Func<Product> fun1=new Func<Product>(foodFactory.MakePizaa);
Func<Product> fun2=new Func<Product>(foodFactory.MakeTC);
box1=wrapfactory1.wrapFactory(fun1);
box2=wrapfactory1.wrapFactory(fun2);
System.Console.WriteLine(box1.product.Name);
System.Console.WriteLine(box2.product.Name);
Console.ReadLine();
}
}
class Product
{
public string Name{get;set;}
}
class Box
{
public Product product { get; set; }
}
class WrapFactory
{
public Box wrapFactory(Func<Product> cproduct)
{
Box box=new Box();
Product product=cproduct.Invoke();
box.product=product;
return box;
}
}
class FoodFactory
{
public Product MakePizaa()
{
Product pizaa=new Product();
pizaa.Name="Pizaa";
return pizaa;
}
public Product MakeTC()
{
Product tc=new Product();
tc.Name="tc";
return tc;
}
}
回调方法
class Program
{
static void Main(string[] args)
{
WrapFactory wrapfactory1=new WrapFactory();
FoodFactory foodFactory=new FoodFactory();
Box box1=new Box();
Box box2=new Box();
Func<Product> fun1=new Func<Product>(foodFactory.MakePizaa);
Func<Product> fun2=new Func<Product>(foodFactory.MakeTC);
Logger log=new Logger();
Action<Product> action=new Action<Product>(log.Log);
box1=wrapfactory1.wrapFactory(fun1,action);
box2=wrapfactory1.wrapFactory(fun2,action);
System.Console.WriteLine(box1.product.Name);
System.Console.WriteLine(box2.product.Name);
Console.ReadLine();
}
}
class Logger
{
public void Log(Product product)
{
System.Console.WriteLine("{0} product was producted in {1} ,pirce is {2}",product.Name,DateTime.UtcNow,product.Price);
}
}
class Product
{
public string Name{get;set;}
public double Price{get;set;}
}
class Box
{
public Product product { get; set; }
}
class WrapFactory
{
public Box wrapFactory(Func<Product> cproduct,Action<Product> logger)
{
Box box=new Box();
Product product=cproduct.Invoke();
if(product.Price>=30)
{
logger.Invoke(product);
}
box.product=product;
return box;
}
}
class FoodFactory
{
public Product MakePizaa()
{
Product pizaa=new Product();
pizaa.Name="Pizaa";
pizaa.Price=20;
return pizaa;
}
public Product MakeTC()
{
Product tc=new Product();
tc.Name="tc";
tc.Price=50;
return tc;
}
}
开启线程
using System.Threading;
多托、多播（一个委托封装多个委托）Action x +=Action y 执行顺序看封装的先后顺序
每个运行程序就是一个进程，一个进程有一个或者多个线程（只有一个线程为主线程，其余都为分支线程）
同步与异步
同步：你做完我再做，是串行、单线程的
异步：同时进行，是并行、多线程的
同步调用：同一线内
异步调用：多线程内，但当争夺同一资源时会有可能冲突。
直接调用函数（直接同步）
static void Main(string[] args)
{
Student stu1=new Student(){ID=1,PenColor=ConsoleColor.Red};
Student stu2=new Student(){ID=2,PenColor=ConsoleColor.Green};
Student stu3=new Student(){ID=3,PenColor=ConsoleColor.Cyan};
stu1.DoHomework();
stu2.DoHomework();
stu3.DoHomework();
for(int i =0;i<5;i++)
{
Console.ForegroundColor=ConsoleColor.DarkYellow;
System.Console.WriteLine("{0} later",i);
Thread.Sleep(1000);
}
Console.ReadLine();
}
}
class Student
{
public int ID { get; set; }
public ConsoleColor PenColor{get;set;}
public void DoHomework()
{
for(int i=0;i<5;i++)
{
Console.ForegroundColor=this.PenColor;
Console.WriteLine("{0}Stuendt do homework with {1} hour",this.ID,i);
Thread.Sleep(1000);
}
}
}
间接同步(委托单播、多播)
class Program
{
static void Main(string[] args)
{
Student stu1=new Student(){ID=1,PenColor=ConsoleColor.Red};
Student stu2=new Student(){ID=2,PenColor=ConsoleColor.Green};
Student stu3=new Student(){ID=3,PenColor=ConsoleColor.Cyan};
Action a=new Action(stu1.DoHomework);
Action b=new Action(stu2.DoHomework);
Action c=new Action(stu3.DoHomework);
//单播委托
// a.Invoke();
// b.Invoke();
// c.Invoke();
//多播
a+=b;
a+=c;
a.Invoke();
for(int i =0;i<5;i++)
{
Console.ForegroundColor=ConsoleColor.DarkYellow;
System.Console.WriteLine("{0} later",i);
Thread.Sleep(1000);
}
Console.ReadLine();
}
}
class Student
{
public int ID { get; set; }
public ConsoleColor PenColor{get;set;}
public void DoHomework()
{
for(int i=0;i<5;i++)
{
Console.ForegroundColor=this.PenColor;
Console.WriteLine("{0}Stuendt do homework with {1} hour",this.ID,i);
Thread.Sleep(1000);
}
}
}
隐式异步
class Program
{
static void Main(string[] args)
{
Student stu1=new Student(){ID=1,PenColor=ConsoleColor.Red};
Student stu2=new Student(){ID=2,PenColor=ConsoleColor.Green};
Student stu3=new Student(){ID=3,PenColor=ConsoleColor.Cyan};
Action a=new Action(stu1.DoHomework);
Action b=new Action(stu2.DoHomework);
Action c=new Action(stu3.DoHomework);
//隐式异步
a.BeginInvoke(null,null);
b.BeginInvoke(null,null);
c.BeginInvoke(null,null);
for(int i =0;i<5;i++)
{
Console.ForegroundColor=ConsoleColor.DarkYellow;
System.Console.WriteLine("{0} later",i);
Thread.Sleep(1000);
}
Console.ReadLine();
}
}
class Student
{
public int ID { get; set; }
public ConsoleColor PenColor{get;set;}
public void DoHomework()
{
for(int i=0;i<5;i++)
{
Console.ForegroundColor=this.PenColor;
Console.WriteLine("{0}Stuendt do homework with {1} hour",this.ID,i);
Thread.Sleep(1000);
}
}
}
显式异步
class Program
{
static void Main(string[] args)
{
Student stu1=new Student(){ID=1,PenColor=ConsoleColor.Red};
Student stu2=new Student(){ID=2,PenColor=ConsoleColor.Green};
Student stu3=new Student(){ID=3,PenColor=ConsoleColor.Cyan};
//Thread显式异步
// Thread a=new Thread(stu1.DoHomework);
// Thread b=new Thread(stu2.DoHomework);
// Thread c=new Thread(stu3.DoHomework);
//Task显式异步
Task a=new Task(stu1.DoHomework);
Task b=new Task(stu2.DoHomework);
Task c=new Task(stu3.DoHomework);
a.Start();
b.Start();
c.Start();
for(int i =0;i<5;i++)
{
Console.ForegroundColor=ConsoleColor.DarkYellow;
System.Console.WriteLine("{0} later",i);
Thread.Sleep(1000);
}
Console.ReadLine();
}
}
class Student
{
public int ID { get; set; }
public ConsoleColor PenColor{get;set;}
public void DoHomework()
{
for(int i=0;i<5;i++)
{
Console.ForegroundColor=this.PenColor;
Console.WriteLine("{0}Stuendt do homework with {1} hour",this.ID,i);
Thread.Sleep(1000);
}
}
}
接口替换委托案例
一般情况下，会用Interface代替委托，因为严重情况下委托会造成内存泄漏，委托属于一种紧耦合的方式，一当回调进里层，将会造成不可debug的后果。
点击查看代码
class Program
{
static void Main(string[] args)
{
WrapFactory wrapfactory1=new WrapFactory();
IProductFactor PizzaFactor=new Pizza();
IProductFactor TcFactory=new Tc();
Box box1=new Box();
Box box2=new Box();
Logger log=new Logger();
Action<Product> action=new Action<Product>(log.Log);
box1=wrapfactory1.wrapFactory(PizzaFactor,action);
box2=wrapfactory1.wrapFactory(TcFactory,action);
System.Console.WriteLine(box1.product.Name);
System.Console.WriteLine(box2.product.Name);
Console.ReadLine();
}
}
interface IProductFactor
{
Product Make();
}
class Pizza:IProductFactor
{
public Product Make()
{
Product pizaa=new Product();
pizaa.Name="Pizaa";
pizaa.Price=20;
return pizaa;
}
}
class Tc:IProductFactor
{
public Product Make()
{
Product tc=new Product();
tc.Name="tc";
tc.Price=50;
return tc;
}
}
class Logger
{
public void Log(Product product)
{
System.Console.WriteLine("{0} product was producted in {1} ,pirce is {2}",product.Name,DateTime.UtcNow,product.Price);
}
}
class Product
{
public string Name{get;set;}
public double Price{get;set;}
}
class Box
{
public Product product { get; set; }
}
class WrapFactory
{
public Box wrapFactory(IProductFactor cproduct,Action<Product> logger)
{
Box box=new Box();
Product product=cproduct.Make();
if(product.Price>=30)
{
logger.Invoke(product);
}
box.product=product;
return box;
}
}
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