1 public class EventStandard 2  { 3 public class Clothes { 4  5 /// <summary> 6 /// 服装编码 7 /// </summary> 8 public string Id { get; set; } 9 10 /// <summary>11 /// 服装名称12 /// </summary>13 public string Name { get; set; }14 15 /// <summary>16 /// 服装价格17 /// </summary>18 private double _price;19 20 public double Price {21 get { return this._price; }22 set {23 PriceRiseHandler?.Invoke(this, new PriceEventArgs()24  {25 OldPrice = this._price,26 NewPrice = value27  });28 this._price = value;29  }30  }31 32 /// <summary>33 /// 服装价格变动事件34 /// </summary>35 public event EventHandler PriceRiseHandler;36 37  }38 39 /// <summary>40 /// 衣服价格事件参数 一般会为特定的事件去封装个参数类型41 /// </summary>42 public class PriceEventArgs : EventArgs43  {44 public double OldPrice { get; set; }45 public double NewPrice { get; set; }46  }47 48 public class TaoBao {49 /// <summary>50 /// 淘宝订户51 /// </summary>52 public void PublishPriceInfo(object sender, EventArgs e) {53 Clothes clothes = (Clothes)sender;54 PriceEventArgs args = (PriceEventArgs)e;55 if (args.NewPrice < args.OldPrice)56 Console.WriteLine($"淘宝：发布衣服价格下降的公告，{clothes.Name}服装直降{args.OldPrice - args.NewPrice}元，限时抢购！");57 else 58 Console.WriteLine("淘宝：价格悄悄上涨或价格未变化，啥也不做");59  }60 61  }62 63 public class Consumer64  {65 /// <summary>66 /// 消费者订户67 /// </summary>68 public void Buy(object sender, EventArgs e)69  {70 Clothes clothes = (Clothes)sender;71 PriceEventArgs args = (PriceEventArgs)e;72 if (args.NewPrice < args.OldPrice)73 Console.WriteLine($"消费者：之前价格{args.OldPrice}，现在价格{args.NewPrice},果断买了！");74 else 75 Console.WriteLine($"消费者：等等看，降价了再说");76  }77  }78 79 public static void Show()80  {81 Clothes clothes = new Clothes()82  {83 Id = "12111-XK",84 Name = "优衣库",85 Price = 12886  };87 //订阅：把订户和发布者的事件关联起来88 clothes.PriceRiseHandler += new TaoBao().PublishPriceInfo;89 clothes.PriceRiseHandler += new Consumer().Buy;90 //价格变化，自动触发订户订阅的事件91 clothes.Price = 300;92  }93 94 }

clothes.Price = 300; EventStandard.Show();

clothes.Price = 98; EventStandard.Show();