使用委托中介租房理解委托与事件

委托和事件，.Net Framework中的应用非常广泛，然而，较好的理解委托和事件对很多接触C#时间不长的人来说并不容易。它们就像一道门槛儿，跨过去的，觉得太容易了，而没有过去的人每次见到委托事件就觉得心慌慌，浑身不自在。

我个人还是比较喜欢用面向对象的编程思想去理解逻辑程序，理解编程。下面就用委托中介公司租房子的示例理解使用委托流程：

1.定义委托和委托对象——租房人想要租房，但是没有房源，于是委托中介找房子；
2.编写要委托的方法——租房中介有房源，可以找到房子；
3.将要委托的方法传递给委托对象——租房人来到租房中介公司，把租房委托传达给中介公司；
4.使用委托调用委托方法——中介公司开始找房子；

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

namespace 使用委托模拟租房
{
    class Program
    {
        static void Main(string[] args)
        {
            Customer customer = new Customer("王天", RoomType.OneBedRoom, 1000);
            Agency agency = new Agency("美家");
            Room room1 = new Room(RoomType.OneBedRoom,1000);
            Room room2 = new Room(RoomType.TwoBedRoom, 3000);
            agency.roomList.Add(room1);
            agency.roomList.Add(room2);
            customer.findRoom = agency.FindRoom;
            customer.FindRoom();
        }
    }
    /// <summary>
    /// 房间类型枚举
    /// </summary>
    public enum RoomType
    {
        OneBedRoom, TwoBedRoom, ThreeBenRoom
    }
    /// <summary>
    /// 房间类
    /// </summary>
    class Room
    {
        public Room(RoomType type,int price)
        {
            this.RoomType = type;
            this.Price = price;
        }
        public RoomType RoomType { get; set; }
        public int Price { get; set; }
    }
    /// <summary>
    /// 客户类
    /// </summary>
    class Customer
    {
        public Customer(string name, RoomType type, int price)
        {
            this.CusName = name;
            this.wantPrice = price;
        }
        public string CusName { get; set; }
        public RoomType wantRoomType { get; set; }
        public int wantPrice { get; set; }
        
        public delegate void LetAgencyToFindRoom(RoomType roomType, int roomPrice);
        public LetAgencyToFindRoom findRoom;
        //让中介找房子的方法
        public void FindRoom()
        {
            Console.WriteLine(CusName + "说：我要找一套" + wantRoomType + "的房子，价格不高于" + wantPrice);
            findRoom(wantRoomType, wantPrice);
        }
    }
    /// <summary>
    /// 中介类
    /// </summary>
    class Agency
    {
        public Agency(string name){

        }
        public string AgencyName { get; set; }
        public List<Room> roomList = new List<Room>();
        public void FindRoom(RoomType type, int roomPrice)
        {
            Console.WriteLine(AgencyName + "中介开始找房子");
            Room room = null;
            foreach (Room r in roomList)
            {
                if (r.RoomType == type && r.Price <= roomPrice)
                {
                    room = r;
                }
            }
            if (room != null)
            {
                Console.WriteLine("找到一套：类型：" + room.RoomType + "价格：" + roomPrice);
            }
            else
            {
                Console.WriteLine("没有找到适合您的房子！");
            }
            Console.ReadLine();
        }
    }
}