C# 委托、事件

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1、Action委托、Func委托

namespace DelegateExample
{
    class Program
    {
        static void main(string[] args)
        {
            Calculator calculator=new Calculator();
            
            //Action委托
            Action Cal=new Action(calculator.Report);
            
            //直接调用函数
            Calculator.Report();
            //通过委托调用函数
            Cal.Invoke();
            //简便写法
            Cal();
            
            
            
            
            //Func委托
            int a=100,b=200,c=0;
          
            Func<int,int,int> func1=new Func<int,int,int>(Calculator.Add); 
            //尖括号中为<参数1，参数2，返回值>
            Func<int,int,int> func2=new Func<int,int,int>(Calculator.Sub);
            //利用委托调用函数
            c=func1.Invoke(a,b);//简便写法 c=func1(a,b)
            Console.WriteLine(c);
            
            c=func2.Invoke(a,b);//简便写法 c=func1(a,b)
            Console.WriteLine(c);
            
            
            
            
        }
    }
    class Calculator
    {
        public void  Report(){
            console.WriteLine("123");
        }
        public int Add(int a,int b){
            int result=a+b;
            return result;
        }
        public int Sub(int a,int b){
            int result=a-b;
            return result;
        }
    }

}

2、自定义委托

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避免写错地方结果声明成嵌套类型：

一般委托的声明在命名空间内，和Program类同级，如果声明在Program类中，会声明成为嵌套类类型。

namespace DelegateExample
{
    //自定义委托声明格式
    public delegate double Cal(double x,double y);
    class Program
    {
     	static void main(string[] args){
            Calculator calculator=new Calculator();
            Cal cal1=new Cal(calculator.Add);
            Cal cal2=new Cal(calculator.Sub);
            Cal cal3=new Cal(calculator.Mul);
            Cal cal4=new Cal(calculator.Div);
		
            double a=200,b=100,c=0;
            c=cal1.invoke(a,b);
            Console.WriteLine(c);
            c=cal2.invoke(a,b);
            Console.WriteLine(c);
            c=cal3.invoke(a,b);
            Console.WriteLine(c);
            c=cal4.invoke(a,b);
            Console.WriteLine(c);
        }   
    }
    class Calculator
    {
        
        public double Add(double a,double b){
            return a+b;
        }
        public double Sub(double a,double b){
            return a-b;
        }
        public double Mul(double a,double b){
            return a*b;
        }
        public double Div(double a,double b){
            return a/b;
        }
    }
    
    
}

3、委托的一般使用

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3.1 模板方法

using System;
using System.Collections.Generic;

namespace DelegateExample
{
    class Program
    {
        static void Main(string[] args)
        {
            WrapFactory wrapFactory = new WrapFactory();
            ProductFactory productFactory = new ProductFactory();

            Func<Product> func1 = new Func<Product>(productFactory.MakePizza);
            Func<Product> func2 = new Func<Product>(productFactory.MakeToyCar);

            Box box1 = wrapFactory.WrapProduct(func1);
            Box box2 = wrapFactory.WrapProduct(func2);

            Console.WriteLine(box1.Product.Name);
            Console.WriteLine(box2.Product.Name);

            Console.ReadKey();
        }
    }

    class Product
    {
        public string Name{ get; set; }
    }
    
    class Box
    {
        public Product Product { get; set; }
    }
    class WrapFactory
    {
        public Box WrapProduct(Func<Product> getProduct)
        {
            Product product = getProduct.Invoke();
            Box box = new Box();
            box.Product = product;
            return box;
        }
        
    }
    class ProductFactory
    {
        public Product MakePizza()
        {
            Product product = new Product();
            product.Name = "Pizza";
            return product;
        }
        public Product MakeToyCar()
        {
            Product product = new Product();
            product.Name = "Toy Car";
            return product;
        }
    }


}
//使用模板方法的好处，代码复用性高，只需要扩充ProductFactory类中的方法
//Product类、WrapFactory类，均不用修改

3.2 回调方法

需求：

使用委托的回调方法，在上述代码中实现，若产品价格大于等于50时，打印输出商品信息

using System;
using System.Collections.Generic;

namespace DelegateExample
{
    class Program
    {
        static void Main(string[] args)
        {
            WrapFactory wrapFactory = new WrapFactory();
            ProductFactory productFactory = new ProductFactory();

            Func<Product> func1 = new Func<Product>(productFactory.MakePizza);
            Func<Product> func2 = new Func<Product>(productFactory.MakeToyCar);

            Logger logger = new Logger();

            Action<Product> log = new Action<Product>(logger.Log);

            Box box1 = wrapFactory.WrapProduct(func1,log);
            Box box2 = wrapFactory.WrapProduct(func2,log);

            Console.WriteLine(box1.Product.Name);
            Console.WriteLine(box2.Product.Name);

            Console.ReadKey();
        }
    }
    
    class Logger
    {
        public void Log(Product product)
        {
            Console.WriteLine("Product '{0}' created at {1}. Price 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 WrapProduct(Func<Product> getProduct,Action<Product> logCallback)
        {
            Product product = getProduct.Invoke();
            if (product.Price >= 50)
            {
                logCallback(product);
            }
            Box box = new Box();
            box.Product = product;
            return box;
        }
        
    }
    class ProductFactory
    {
        public Product MakePizza()
        {
            Product product = new Product();
            product.Name = "Pizza";
            product.Price = 20;
            return product;
        }
        public Product MakeToyCar()
        {
            Product product = new Product();
            product.Name = "Toy Car";
            product.Price = 99;
            return product;
        }
    }


}

3.3 委托的高级使用

同步与异步的概念：与中文不同

多播委托

using System;
using System.Collections.Generic;
using System.Threading;
namespace DelegateExample 
{
    class Program
    {
        static void Main(string[] args)
        {
            Student stu1 = new Student() { ID = 1, PenColor = ConsoleColor.Yellow };
            Student stu2 = new Student() { ID = 1, PenColor = ConsoleColor.Green };
            Student stu3 = new Student() { ID = 1, PenColor = ConsoleColor.Red };

            Action action1 = new Action(stu1.DoHomeWork);
            Action action2 = new Action(stu2.DoHomeWork);
            Action action3= new Action(stu3.DoHomeWork);
            //单播委托
            /*action1.Invoke();
            action2.Invoke();
            action3.Invoke();*/


            //多播委托
            action1 += action2;
            action1 += action3;
            action1.Invoke();


            Console.ReadKey();
        }
    }
    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("Student {0} doing homework {1} hour(s).", this.ID, i);
                Thread.Sleep(1000);
            }
        }

    }
    
    


}

隐式异步调用

首先了解一下同步调用

直接同步调用与间接同步调用

using System;
using System.Collections.Generic;
using System.Threading;
namespace DelegateExample 
{
    class Program
    {
        static void Main(string[] args)
        {
            Student stu1 = new Student() { ID = 1, PenColor = ConsoleColor.Yellow };
            Student stu2 = new Student() { ID = 1, PenColor = ConsoleColor.Green };
            Student stu3 = new Student() { ID = 1, PenColor = ConsoleColor.Red };

            //直接同步调用
            /*stu1.DoHomeWork();
            stu2.DoHomeWork();
            stu3.DoHomeWork();*/

            //间接同步调用
            Action action1 = new Action(stu1.DoHomeWork);
            Action action2 = new Action(stu2.DoHomeWork);
            Action action3 = new Action(stu3.DoHomeWork);

            action1.Invoke();
            action2.Invoke();
            action3.Invoke();
            //或者使用多播委托,也是同步调用的
            //action1+=action2;action1+=action3;action1.Invoke();
            

            for (int i = 0; i < 10; i++)
            {
                Console.ForegroundColor = ConsoleColor.Cyan;
                Console.WriteLine("Main thread {0}.", i);
                Thread.Sleep(1000);
            }

            Console.ReadKey();
        }
    }
    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("Student {0} doing homework {1} hour(s).", this.ID, i);
                Thread.Sleep(1000);
            }
        }

    }
}

异步调用

隐式异步调用

using System;
using System.Collections.Generic;
using System.Threading;
namespace DelegateExample 
{
    class Program
    {
        static void Main(string[] args)
        {
            Student stu1 = new Student() { ID = 1, PenColor = ConsoleColor.Yellow };
            Student stu2 = new Student() { ID = 1, PenColor = ConsoleColor.Green };
            Student stu3 = new Student() { ID = 1, PenColor = ConsoleColor.Red };

            
           
            //隐式异步调用
            Action action1 = new Action(stu1.DoHomeWork);
            Action action2 = new Action(stu2.DoHomeWork);
            Action action3 = new Action(stu3.DoHomeWork);
            action1.BeginInvoke(null,null);
            action2.BeginInvoke(null, null);
            action3.BeginInvoke(null, null);

            for (int i = 0; i < 10; i++)
            {
                Console.ForegroundColor = ConsoleColor.Cyan;
                Console.WriteLine("Main thread {0}.", i);
                Thread.Sleep(1000);
            }

            Console.ReadKey();
        }
    }
    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("Student {0} doing homework {1} hour(s).", this.ID, i);
                Thread.Sleep(1000);
            }
        }

    }
    
    


}

显式异步调用(古老的方式：使用Thread进行显示异步调用)

using System;
using System.Collections.Generic;
using System.Threading;
namespace DelegateExample 
{
    class Program
    {
        static void Main(string[] args)
        {
            Student stu1 = new Student() { ID = 1, PenColor = ConsoleColor.Yellow };
            Student stu2 = new Student() { ID = 1, PenColor = ConsoleColor.Green };
            Student stu3 = new Student() { ID = 1, PenColor = ConsoleColor.Red };


            /*            
            Action action1 = new Action(stu1.DoHomeWork);
            Action action2 = new Action(stu2.DoHomeWork);
            Action action3 = new Action(stu3.DoHomeWork);

            //隐式异步调用
            action1.BeginInvoke(null,null);
            action2.BeginInvoke(null, null);
            action3.BeginInvoke(null, null);
            */

            //使用Thread进行显式异步调用
            Thread thread1 = new Thread(new ThreadStart(stu1.DoHomeWork));
            Thread thread2 = new Thread(new ThreadStart(stu2.DoHomeWork));
            Thread thread3 = new Thread(new ThreadStart(stu3.DoHomeWork));

            thread1.Start();
            thread2.Start();
            thread3.Start();

            for (int i = 0; i < 10; i++)
            {
                Console.ForegroundColor = ConsoleColor.Cyan;
                Console.WriteLine("Main thread {0}.", i);
                Thread.Sleep(1000);
            }

            Console.ReadKey();
        }
    }
    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("Student {0} doing homework {1} hour(s).", this.ID, i);
                Thread.Sleep(1000);
            }
        }

    }
}

显式异步调用更高级的方式:Task,需要引用System.Threading.Tasks命名空间

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
namespace DelegateExample 
{
    class Program
    {
        public static object TTask { get; private set; }

        static void Main(string[] args)
        {
            Student stu1 = new Student() { ID = 1, PenColor = ConsoleColor.Yellow };
            Student stu2 = new Student() { ID = 1, PenColor = ConsoleColor.Green };
            Student stu3 = new Student() { ID = 1, PenColor = ConsoleColor.Red };


            /*            
            Action action1 = new Action(stu1.DoHomeWork);
            Action action2 = new Action(stu2.DoHomeWork);
            Action action3 = new Action(stu3.DoHomeWork);

            //隐式异步调用
            action1.BeginInvoke(null,null);
            action2.BeginInvoke(null, null);
            action3.BeginInvoke(null, null);
            */

            //使用Thread进行显式异步调用
            /*Thread thread1 = new Thread(new ThreadStart(stu1.DoHomeWork));
            Thread thread2 = new Thread(new ThreadStart(stu2.DoHomeWork));
            Thread thread3 = new Thread(new ThreadStart(stu3.DoHomeWork));

            thread1.Start();
            thread2.Start();
            thread3.Start();*/

            //更高级的方式，使用Task进行显式异步调用
            Task task1 = new Task(new Action(stu1.DoHomeWork));
            Task task2 = new Task(new Action(stu2.DoHomeWork));
            Task task3 = new Task(new Action(stu3.DoHomeWork));

            task1.Start();
            task2.Start();
            task3.Start();


            for (int i = 0; i < 10; i++)
            {
                Console.ForegroundColor = ConsoleColor.Cyan;
                Console.WriteLine("Main thread {0}.", i);
                Thread.Sleep(1000);
            }

            Console.ReadKey();
        }
    }
    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("Student {0} doing homework {1} hour(s).", this.ID, i);
                Thread.Sleep(1000);
            }
        }

    }
}

最好用接口代替委托

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用接口代替第一个案例中的委托

using System;
using System.Collections.Generic;

namespace DelegateExample
{
    class Program
    {
        static void Main(string[] args)
        {

            IProductFactory pizzaFactory = new PizzaFactory();
            IProductFactory toyCarFactory = new ToyCarFactory();
            WrapFactory wrapFactory = new WrapFactory();
            
            
            Box box1 = wrapFactory.WrapProduct(pizzaFactory);
            Box box2 = wrapFactory.WrapProduct(toyCarFactory);

            Console.WriteLine(box1.Product.Name);
            Console.WriteLine(box2.Product.Name);

            Console.ReadKey();
        }
    }

    interface IProductFactory
    {
        Product Make();
    }
    class PizzaFactory : IProductFactory
    {
        public Product Make()
        {
            Product product = new Product();
            product.Name = "Pizza";
            return product;
        }
    }
    class ToyCarFactory : IProductFactory
    {
        public Product Make()
        {
            Product product = new Product();
            product.Name = "Toy Car";
            return product;
        }
            
    }

    class Product
    {
        public string Name { get; set; }
        public double Price { get; set; }
    }

    class Box
    {
        public Product Product { get; set; }
    }
    class WrapFactory
    {
        public Box WrapProduct(IProductFactory productFactory)
        {
            Product product = productFactory.Make();
            Box box = new Box();
            box.Product = product;
            return box;
        }

    }
}

事件

1.初步了解

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统一称为事件的订阅者

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统一称为事件参数

2.动手操作
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1.事件的简单示例

using System;
using System.Timers;
namespace EventExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Timer timer = new Timer();//timer为事件的拥有者
            timer.Interval = 1000;
            Boy boy = new Boy();//boy为事件的订阅者
            Girl girl = new Girl();
            timer.Elapsed += boy.Action;
            timer.Elapsed += girl.Action;
            timer.Start();
            Console.ReadLine();
        }
    }
    class Boy
    {
        internal void Action(object sender, ElapsedEventArgs e)
        {
            Console.WriteLine("Jump!");
        }
    }

    class Girl
    {
        internal void Action(object sender, ElapsedEventArgs e)
        {
            Console.WriteLine("Sing!");
        }
    }

}

示例2

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using System;
using System.Windows.Forms;

namespace EventExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Form form = new Form();//form是事件的拥有者
            Controller controller = new Controller(form);//controller是事件的订阅者
            form.ShowDialog();
        }
    }
    
    class Controller
    {
        private Form form;
        public Controller(Form form)
        {
            if (form != null)
            {
                this.form = form;
                this.form.Click += this.FormClicked;//form.Click是事件成员，FromClicked是事件处理器
            }
        }

        private void FormClicked(object sender, EventArgs e)
        {
            this.form.Text = DateTime.Now.ToString();
        }
    }
}

3.示例3
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using System;
using System.Windows.Forms;

namespace EventExample
{
    class Program
    {
        static void Main(string[] args)
        {
            MyForm form = new MyForm();//form事件拥有者
            form.Click += form.FormClicked;//事件成员form.Click;事件处理器form.FormClicked;
                                           //事件订阅者也是form;
            form.ShowDialog();
        }
    }
    class MyForm : Form
    {
        internal void FormClicked(object sender, EventArgs e)
        {
            this.Text = DateTime.Now.ToString();
        }
    }
}

4.示例4

using System;
using System.Windows.Forms;

namespace EventExample
{
    class Program
    {
        static void Main(string[] args)
        {
            MyForm form = new MyForm();
            form.ShowDialog();
        }
       
    }
    
    class MyForm : Form
    {
        private TextBox textBox;
        private Button button;//事件拥有者是实例化的 Form.button
        public MyForm()
        {
            this.textBox = new TextBox();
            this.button = new Button();
            this.Controls.Add(this.button);
            this.Controls.Add(this.textBox);
            this.button.Click += ButtonClicked;//button.Click是事件成员，
                                               //ButtonClicked是事件处理器
                                               //事件订阅者是MyForm的实例
        }

        private void ButtonClicked(object sender, EventArgs e)
        {
            this.textBox.Text = "Hello, World!";
        }
    }
}

委托、事件

C# 委托、事件
- 1、Action委托、Func委托
- 2、自定义委托
- 3、委托的一般使用
- - 3.1 模板方法
  - 3.2 回调方法
  - 3.3 委托的高级使用
  - - 同步与异步的概念：与中文不同
    - 多播委托
    - **隐式异步调用**
    - **异步调用**
  - 最好用接口代替委托
事件