事件与委托

Posted 2020-08-30 墨尔本

参考文章：http://blog.csdn.net/wufeng4552/article/details/6261779

代码实现以下功能：主人回来了，猫叫了一声，老鼠被吓跑了同事吵醒了小孩。

以下是类图：

 

以下是实现代码：

\'\'\' <summary>
\'\'\' 主人
\'\'\' </summary>
\'\'\' <remarks></remarks>
Public Class Master
    \'\'\' <summary>
    \'\'\' 主人到家事件
    \'\'\' </summary>
    \'\'\' <remarks></remarks>
    Public Event ReachHomeEvent As ReachHomeEventHandler

    \'\'\' <summary>
    \'\'\' 主人回家过程
    \'\'\' </summary>
    \'\'\' <remarks></remarks>
    Public Sub BackHome()
        Walk()
        RaiseEvent ReachHomeEvent(Me)
    End Sub

    \'\'\' <summary>
    \'\'\' 步行
    \'\'\' </summary>
    \'\'\' <remarks></remarks>
    Public Sub Walk()
        Console.WriteLine("步行回家")
        Threading.Thread.Sleep(800)
    End Sub
End Class

Public Delegate Sub ReachHomeEventHandler(ByVal sender As Object)

 

\'\'\' <summary>
\'\'\' 猫
\'\'\' </summary>
\'\'\' <remarks></remarks>
Public Class Cat
    \'\'\' <summary>
    \'\'\' 猫叫
    \'\'\' Master.ReachHomeEvent事件的事件处理程序
    \'\'\' </summary>
    \'\'\' <remarks></remarks>
    Public Sub Mao(ByVal sender As Object)
        Console.WriteLine("Miao")
        RaiseEvent MaoEvent(Me, New EventArgs())
    End Sub

    \'\'\' <summary>
    \'\'\' 猫叫事件
    \'\'\' </summary>
    \'\'\' <remarks></remarks>
    Public Event MaoEvent As EventHandler

End Class

 

Public Class Mouse

    Public Sub Escape(ByVal sender As Object, ByVal e As EventArgs)
        Console.WriteLine("猫来了，赶紧跑！")
    End Sub

End Class

 

Public Class Children



    \'\'\' <summary>
    \'\'\' 小孩哭
    \'\'\' Master.ReachHomeEvent的事件处理程序
    \'\'\' </summary>
    \'\'\' <remarks></remarks>
    Public Sub Cry()
        Console.WriteLine("呜呜呜")
    End Sub

    \'\'\' <summary>
    \'\'\' 小孩醒来
    \'\'\' </summary>
    \'\'\' <param name="sender"></param>
    \'\'\' <param name="e"></param>
    \'\'\' <remarks></remarks>
    Public Sub WakeUp(ByVal sender As Object, ByVal e As EventArgs)
        Cry()
    End Sub

End Class

 

Module Module1
    Private WithEvents _master As Master
    Private WithEvents _cat As Cat
    Private WithEvents _child As Children
    Sub Main()
        Dim _mouse As Mouse
        _master = New Master()
        _cat = New Cat()
        _child = New Children()
        _mouse = New Mouse()

        \'_cat监视_master
        AddHandler _master.ReachHomeEvent, AddressOf _cat.Mao
        \'_mouse监视_cat
        AddHandler _cat.MaoEvent, AddressOf _mouse.Escape

        \'_child监视_cat
        AddHandler _cat.MaoEvent, AddressOf _child.WakeUp

        _master.BackHome()

        Console.ReadKey()
    End Sub

End Module