C#_ Observer pattern

Suppose there is a software company that notifies a number of customers whenever a new product is introduced.

Abstract the notification action as an interface.

    public interface IService

    {

        void Notif ();

    }

Customers need to implement the above interfaces if they want to be notified. The clients here are seen as observers.

    public class Customera:iservice

    {       

        public void Notif ()

        {

            Console.WriteLine ("Customer A has received the notice ~ ~");

        }

    }

    public class Customerb:iservice

    {

        public void Notif ()

        {

            Console.WriteLine ("Customer B received the notice ~ ~");

        }

    }

As a software company, it maintains a collection of customers and provides a way to register, unregister, and add or remove customers to this collection. Whenever there is a notification, iterate through the customer collection and let IService execute the notification. A software company can be seen as an object of observation, or a source of initiating action.

    public class MyCompany

    {

        Private ilist<iservice> subscribers = new list<iservice> ();

        public void Subscribe (IService subscriber)

        {

            Subscribers. ADD (subscriber);

        }

        public void Cancelsubscribe (IService subscriber)

        {

            Subscribers. Remove (subscriber);

        }

        public void sendmsg ()

        {

            foreach (IService service in subscribers)

            {

                Service. Notif ();

            }

        }

    }

The client creates a software company instance, creates an observer instance, registers or cancels the observer, and so on.

    Class Program

    {

        static void Main (string[] args)

        {

            MyCompany company = new MyCompany ();

            IService Customera = new Customera ();

            IService Customerb = new Customerb ();

            Company. Subscribe (Customera);

            Company. Subscribe (Customerb);

            Company. Sendmsg ();

            Console.readkey ();

        }

    }

Summarize:

Abstract the action of a notification into an interface
Observers implement notification interfaces if they want to receive notifications
3 Things to be observed: maintain a collection of observers, register/Cancel observers, initiate an action traversal observer collection let the notification interface do things

C#_ Observer pattern