C# 設計模式無廢話系列十九：觀察者模式（二）—— 完整範例程式碼

完整範例程式碼

using System;
using System.Collections.Generic;
using System.Text;

namespace ObserverExample
{
    class Program
    {
        static void Main(string[] args)
        {
            ButtonPager buttonPager = new ButtonPager();
            ListPager listPager = new ListPager();
            Control gridview = new GridVIEW();
            Control label = new Label();

            buttonPager.changePageHandler += new Pager.ChangePageHandler(buttonPager.ChangePage);
            buttonPager.changePageHandler += new Pager.ChangePageHandler(gridview.ChangePage);
            buttonPager.changePageHandler += new Pager.ChangePageHandler(label.ChangePage);
            buttonPager.changePageHandler += new Pager.ChangePageHandler(listPager.ChangePage);

            listPager.changePageHandler += new Pager.ChangePageHandler(buttonPager.ChangePage);
            listPager.changePageHandler += new Pager.ChangePageHandler(gridview.ChangePage);
            listPager.changePageHandler += new Pager.ChangePageHandler(label.ChangePage);
            listPager.changePageHandler += new Pager.ChangePageHandler(listPager.ChangePage);

            buttonPager.NextPage();
            Console.WriteLine();
            buttonPager.NextPage();
            Console.WriteLine();
            buttonPager.NextPage();
            Console.WriteLine();
            buttonPager.PreviousPage();
            Console.WriteLine();
            buttonPager.PreviousPage();
            Console.WriteLine();
            listPager.SelectPage(2);
            Console.WriteLine();
            listPager.SelectPage(1);
            Console.WriteLine();
            listPager.SelectPage(0);
        }
    }

    abstract class Pager
    {
        protected int pageIndex = 0;
        public int PageIndex { get { return pageIndex; } set { pageIndex = value; } }

        protected int pageCount = 3;
        public int PageCount { get { return pageCount; } }

        public event ChangePageHandler changePageHandler;
        public delegate void ChangePageHandler(Pager sender);

        protected void ChangePage()
        {
            if (changePageHandler != null)
                changePageHandler(this);
        }
    }

    class ButtonPager : Pager, Control
    {
        public void NextPage()
        {
            if (pageIndex < pageCount - 1)
            {
                Console.WriteLine("Click NextPage Button...");
                pageIndex++;
                ChangePage();
            }
        }

        public void PreviousPage()
        {
            if (pageIndex > 0)
            {
                Console.WriteLine("Click PreviousPage Button...");
                pageIndex--;
                ChangePage();
            }
        }

        public void ChangePage(Pager sender)
        {
            base.pageIndex = sender.PageIndex;
            if (pageIndex > 0 && pageIndex < pageCount - 1)
                Console.WriteLine("<<Previous Next>>");
            else if (pageIndex == 0)
                Console.WriteLine("Next>>");
            else
                Console.WriteLine("<<Previous");
        }
    }

    class ListPager : Pager, Control
    {
        public void SelectPage(int pageIndex)
        {
            if (pageIndex >= 0 && pageIndex < pageCount)
            {
                Console.WriteLine(string.Format("Click <{0}> Link...", pageIndex + 1));
                base.pageIndex = pageIndex;
                ChangePage();
            }
        }

        public void ChangePage(Pager sender)
        {
            base.pageIndex = sender.PageIndex;
            for (int i = 1; i <= pageCount; i++)
            {
                if (pageIndex + 1 == i)
                    Console.Write(string.Format(" <{0}> ", i));
                else
                    Console.Write(string.Format(" {0} ", i));
            }
            Console.WriteLine();
        }
    }

    interface Control
    {
        void ChangePage(Pager sender);
    }

    class GridVIEW : Control
    {
        public void ChangePage(Pager sender)
        {
            Console.WriteLine(string.Format("GridVIEW->Show data of page {0}", sender.PageIndex + 1));
        }
    }

    class Label : Control
    {
        public void ChangePage(Pager sender)
        {
            Console.WriteLine(string.Format("Label.Text=[{0}/{1}]", sender.PageIndex + 1, sender.PageCount));
        }
    }
}