关于Events事件的简单Demo.

目录结构：

Program.cs

1 using System; 2 namespace EventsDemo 3 { 4     class Program 5     { 6         static void Main(string[] args) 7         { 8             Book book = new Book(); 9             book.BookAdded += OnBookAdded;10             book.AddBook("One");11             book.BookAdded -= OnBookAdded;12             book.AddBook("Two");13             book.BookAdded += OnBookAdded;14             book.AddBook("Three");15             book.BookAdded -= OnBookAdded;16             book.AddBook("Four");17         }18         static void OnBookAdded(object sender, EventArgs args)19         {20             System.Console.WriteLine("A book was added");21         }22     }23 }

Book.cs

1 using System; 2 namespace EventsDemo 3 { 4     public delegate void BookAddedDelegate(object sender, EventArgs args); 5     class Book 6     { 7         public void AddBook(string bookname) 8         { 9             if (BookAdded != null)10             {11                 BookAdded(this, new EventArgs());12                 System.Console.WriteLine($"BookName:{bookname}");13             }14         }15         public event BookAddedDelegate BookAdded;16     }17 }

输出：