c#学习-（委托的高级使用）

一、多播委托（multicast）&& 单播委托

        一个委托内部封装不止一个方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
namespace six_multicast
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Student student = new Student() { Id=1,PenColor = ConsoleColor.Yellow};
            Student student2 = new Student() { Id = 2,PenColor = ConsoleColor.Red};
            Student student3 = new Student() { Id = 3, PenColor = ConsoleColor.Green };
 
            Action action1 = new Action(student.DoHomeWork);
            Action action2 = new Action(student2.DoHomeWork);
            Action action3 = new Action(student3.DoHomeWork);
 
            //单播
            action1.Invoke();
            action2.Invoke();
            action3.Invoke();
 
            //多播
            action1 += action2;
            action1 += action3;
 
            action1.Invoke();
        }
    }
    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 is {0} do homework {1} hour(s)", this.Id, i);
                Thread.Sleep(1000);
            }
        }
    }
 
}

二、同步调用

每一个允许的程序是一个进程（Process）

每个进程可以有多个线程（Thread）

同步调用是在一个线程里

串行==同步==单线程

同步调用三种形式

        1、直接同步调用

        2、单播委托的间接调用

        3、多播委托的间接调用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
 
namespace six_multicast
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Student student = new Student() { Id=1,PenColor = ConsoleColor.Yellow};
            Student student2 = new Student() { Id = 2,PenColor = ConsoleColor.Red};
            Student student3 = new Student() { Id = 3, PenColor = ConsoleColor.Green };
 
            Action action1 = new Action(student.DoHomeWork);
            Action action2 = new Action(student2.DoHomeWork);
            Action action3 = new Action(student3.DoHomeWork);
            //同步调用
            //在一根主线程上面执行（创建对象），当有方法执行的时候就去执行方法，然后继续执行主线程，最后主线程还有些事情要做
            //直接调用
            student.DoHomeWork();
            student2.DoHomeWork();
            student3.DoHomeWork();
 
            //单播(单波委托的间接调用)
            action1.Invoke();
            action2.Invoke();
            action3.Invoke();
 
            //多播（多播委托的间接调用）
               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);
            }
        }
    }
    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 is {0} do homework {1} hour(s)", this.Id, i);
                Thread.Sleep(1000);
            }
        }
    }
 
}

三、异步调用

同时进行，多个线程，底层原理=多线程

并行=异步=多线程

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
namespace six_multicast
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Student student = new Student() { Id=1,PenColor = ConsoleColor.Yellow};
            Student student2 = new Student() { Id = 2,PenColor = ConsoleColor.Red};
            Student student3 = new Student() { Id = 3, PenColor = ConsoleColor.Green };
 
            Action action1 = new Action(student.DoHomeWork);
            Action action2 = new Action(student2.DoHomeWork);
            Action action3 = new Action(student3.DoHomeWork);
 
            //异步调用（多个线程争抢一个资源，会起冲突）
            //显示异步掉用(老方式)
            Thread thread = new Thread(new ThreadStart(student.DoHomeWork));
            Thread thread2 = new Thread(new ThreadStart(student2.DoHomeWork));
            Thread thread3 = new Thread(new ThreadStart(student3.DoHomeWork));
 
            thread.Start();
            thread2.Start();
            thread3.Start();
            //显示异步调用（新方式）
            Task task = new Task(new Action(student.DoHomeWork));
            Task task1 = new Task(new Action(student2.DoHomeWork));
            Task task2 = new Task(new Action(student3.DoHomeWork));
 
            task.Start();
            task1.Start();
            task2.Start();
            //隐式异步调用
            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);
            }
        }
    }
    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 is {0} do homework {1} hour(s)", this.Id, i);
                Thread.Sleep(1000);
            }
        }
    }
 
}

总结：

        应该慎重的使用委托

        对于为什么会造成内存泄漏和程序性能下降原因

        委托会引用一个方法，这个方法如果是一个实例方法的话，那么这个方法必定会隶属于一个对象，你拿一个委托引用了这个方法，那么这个对象就必须存在于内存当中，即便是没有其他的引用变量引用这个对象，因为你一释放这个内存，委托就不能够间接去调用对象的方法，所以所委托有可能造成内存泄漏，随着泄漏的内存越来越多，程序就会崩溃

        使用异步会导致出现多个线程争抢资源的情况，会出现冲突，可以加上线程锁，另外，应该合适的使用接口interface取代一些对委托的使用

        下面两个分别是使用接口interface与使用委托delegate，最终的实现都是一样

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace six_InterfaceDelegate
{
    internal class Program
    {
        static void Main(string[] args)
        {
            WrapFactory wrapFactory = new WrapFactory();
            IProductFactory MakePizza = new MakePizza();
            IProductFactory MakeCar = new MakeCar();
 
            Box box = wrapFactory.ProductFactory(MakePizza);
            Box box2 = wrapFactory.ProductFactory(MakeCar);
 
            Console.WriteLine(box.Product.Name);
            Console.WriteLine(box2.Product.Name);
        }
    }
 
    interface IProductFactory
    {
        Product Make();
    }
    class MakePizza : IProductFactory
    {
        public Product Make()
        {
            Product product = new Product();
            product.Name = "Pizza";
            return product;
        }
    }
 
    class MakeCar : IProductFactory
    {
        public Product Make()
        {
            Product product = new Product();
            product.Name = "Car";
            return product;
        }
    }
    class Product
    {
        public string Name { get; set; }
    }
 
    class Box
    {
        public Product Product { get; set; }
    }
 
    class WrapFactory
    {
        public Box ProductFactory(IProductFactory productFactory)
        {
            Box box = new Box();
            Product product = productFactory.Make();
            box.Product = product;
            return box;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
/*
    演示了如何使用委托和模板方法来包装产品
 */
namespace four_GreateDelegate2
{
    internal class Program
    {
        static void Main(string[] args)
        {
           
            ProductFactory productFactory = new ProductFactory();
            
            WrapFactory wrapFactory = new WrapFactory();
            
            Func func1 = new Func(productFactory.MakePizza);
            Func func2 = new Func(productFactory.MakeToCar);
 
            
            
            Box box1 = wrapFactory.WrapProduct(func1);
            Box box2 = wrapFactory.WrapProduct(func2);
 
            Console.WriteLine(box1.Product.Name);
            Console.WriteLine(box2.Product.Name);
 
        }
    }
 
    class Product//产品
    {
        public string Name { get; set; }
    }
 
    class Box//箱子
    {
        public Product Product { get; set; }
    }
 
    class WrapFactory
    {
       
        public Box WrapProduct(Func getProduct)
        {
            Box box = new Box();
            
            Product product = getProduct.Invoke();
            
            box.Product = product;
 
            return box;
        }
    }
 
    class ProductFactory
    {
        public Product MakePizza()
        {
            
            Product product = new Product();
            product.Name = "Pizza";
            return product;
        }
 
        public Product MakeToCar()
        {
            Product product = new Product();
            product.Name = "Toy Car";
            return product ;
        }
    }
}