事件2 (标准 EventHandler)

标签：

• EventHandler: 能提供一个对于所有事件和事件处理器都通用的签名,只允许两个参数,(而不是各自都有不同签名)
  • Object sender , //用来保存除非时间的对象引用,由于为object类型的,所以可以匹配任何类型的参数
  • EventArgs e , //用来保存状态信息,(或用户传递数据,需继承该类)

    namespace System

    {

    // Summary:

    // Represents the method that will handle an event.

    //

    // Parameters:

    // sender:

    // The source of the event.

    //

    // e:

    // An System.EventArgs that contains the event data.

    //

    // Type parameters:

    // TEventArgs:

    // The type of the event data generated by the event.

    [Serializable]

    public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e); //注意这个是模板

    }

    ? ? ?

  • EventArgs

    namespace System

    {

    // Summary:

    // System.EventArgs is the base class for classes containing event data.

    [Serializable]

    [ComVisible(true)]

    public class EventArgs

    {

    // Summary:

    // Represents an event with no event data.

    public static readonly EventArgs Empty;

    ? ? ?

    // Summary:

    // Initializes a new instance of the System.EventArgs class.

    public EventArgs();

    }

    }

  • 扩展EventArgs来传递数据

    

    ? ? ?

    /////////////////////////////////////////////////////////////////

  • 示例:

    public class IncrementerEventArgs : EventArgs // Custom class derived from EventArgs

    {

    public int IterationCount { get; set; } // Stores an integer

    }

    ? ? ?

    class Incrementer

    {

    public event EventHandler<IncrementerEventArgs> CountedADozen;

    ? ? ?

    public void DoCount()

    {

    IncrementerEventArgs args = new IncrementerEventArgs();

    for ( int i=1; i < 100; i++ )

    if ( i % 12 == 0 && CountedADozen != null )

    {

    args.IterationCount = i;

    CountedADozen( this, args );

    }

    }

    }

    ? ? ?

    class Dozens

    {

    public int DozensCount { get; private set; }

    ? ? ?

    public Dozens( Incrementer incrementer )

    {

    DozensCount = 0;

    incrementer.CountedADozen += IncrementDozensCount;

    }

    ? ? ?

    void IncrementDozensCount( object source, IncrementerEventArgs e )

    {

    Console.WriteLine( "Incremented at iteration: {0} in {1}",

    e.IterationCount, source.ToString() );

    DozensCount++;

    }

    }

    ? ? ?

    class Program

    {

    static void Main()

    {

    Incrementer incrementer = new Incrementer();

    Dozens dozensCounter = new Dozens( incrementer );

    ? ? ?

    incrementer.DoCount();

    Console.WriteLine( "Number of dozens = {0}",

    dozensCounter.DozensCount );

    }

    }

  • ?

事件2 (标准 EventHandler)

标签：

原文地址：http://www.cnblogs.com/InspiringMind/p/5858241.html