事件2 (标准 EventHandler)
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- 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
}
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- 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;
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// Summary:
// Initializes a new instance of the System.EventArgs class.
public EventArgs();
}
}
- 扩展EventArgs来传递数据
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/////////////////////////////////////////////////////////////////
- 示例:
public class IncrementerEventArgs : EventArgs // Custom class derived from EventArgs
{
public int IterationCount { get; set; } // Stores an integer
}
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class Incrementer
{
public event EventHandler<IncrementerEventArgs> CountedADozen;
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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 );
}
}
}
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class Dozens
{
public int DozensCount { get; private set; }
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public Dozens( Incrementer incrementer )
{
DozensCount = 0;
incrementer.CountedADozen += IncrementDozensCount;
}
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void IncrementDozensCount( object source, IncrementerEventArgs e )
{
Console.WriteLine( "Incremented at iteration: {0} in {1}",
e.IterationCount, source.ToString() );
DozensCount++;
}
}
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class Program
{
static void Main()
{
Incrementer incrementer = new Incrementer();
Dozens dozensCounter = new Dozens( incrementer );
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incrementer.DoCount();
Console.WriteLine( "Number of dozens = {0}",
dozensCounter.DozensCount );
}
}
- ?
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