基于泛型的事件处理演示与净值2005

Posted 2021-02-27

Annotated version of the Microsoft/GotDotNet demo from the MSDN Wiki.

//Define a custom EventArgs class to contain your data.  
  public class MyEventArgs : EventArgs
  {
    public string info = "data";
  }
 
//Declare the event as visible to users of the class
 
  public event EventHandler<MyEventArgs> MyEvent;
 
 
//Send the event, note that this will throw a nullref if there are no subscribers 
 
  //Internal version prevents outsiders from needing to know about the contents of MyEventArgs
  protected virtual void InternalSendMyEvent(CustomEventArgs e)
  {
    if(MyEvent != null)
    {
      e.info = "Hello Events!"; 
      //This calls all registered subscribers with the following parameters.   
      MyEvent(this, e);
    }
  }
 
  //Public version to allow outsiders to trigger the event, not typical implementation.   
  public void CreateEvent()
  {
    InternalSendMyEvent(new MyEventArgs());
  }
 
 
 
//Consumer
//Register the Handler
 
  eventRaiser.MyEvent += new EventHandler<CustomEventArgs>(HandleEvent);
 
//Define the Handler
  private void HandleEvent(object sender, MyEventArgs e)
  {
    MessageBox.Show("Event handled:" + e.info);
  }
 
 
//Cause the Event
  eventRaiser.CreateEvent();