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Unity 1.x 中文文档：7.2 - 漫游：Unity 事件拦截扩展快速入门

• EventBroker。该项目实现了一个简单的支持多事件的发布和订阅功能。
• EventBrokerExtension。该项目允许在应用程序种使用自定义的容器扩展来发布和订阅事件。
• StopLight。该项目和 Unity StopLight 快速入门相同，但是这里它使用了自定义的用户容器来管理事件的发布和订阅。

图1 EventBroker 扩展快速入门的架构、类和结构

• Program类在容器组件中注册了类型的映射,并且调用Resolve 方法来实例化StopLight 窗体,并且将SimpleEventBrokerExtension 添加至容器组件中。
• SimpleEventBrokerExtension继承自UnityContainerExtension 基类,创建了EventBroker类的实例,EventBroker类发布和订阅了分布式事件。
• EventBroker 类创建了PublishedEvent 类的实例,PublishedEvent 类则为维护事件订阅队列和事件订阅者提供了一个操作的方式。
• StopLightPresenter,StopLightSchedule和RealTimeTimer 类用SimpleEventBrokerExtension类 为事件订阅者和事件发布提供了一些特性。

• 创建自定义Unity 容器的扩展
• 在运行时将扩展加入到Unity 容器
• 使用事件捕获的扩展范例

public class SimpleEventBrokerExtension : UnityContainerExtension,
                                          ISimpleEventBrokerConfiguration
{
  private EventBroker broker = new EventBroker();

  protected override void Initialize()
  {
    Context.Locator.Add(typeof(EventBroker), broker);
    Context.Strategies.AddNew<EventBrokerReflectionStrategy>(UnityBuildStage.PreCreation);
    Context.Strategies.AddNew<EventBrokerWireupStrategy>(UnityBuildStage.Initialization);
  }

  public EventBroker Broker
  {
    get { return broker; }
  }
}

Public Class SimpleEventBrokerExtension
    Inherits UnityContainerExtension
    Implements ISimpleEventBrokerConfiguration

  Private _broker As New EventBroker()

  Protected Overloads Overrides Sub Initialize()
    Context.Locator.Add(GetType(EventBroker), _broker)
    Context.Strategies.AddNew(Of EventBrokerReflectionStrategy)(UnityBuildStage.PreCreation)
    Context.Strategies.AddNew(Of EventBrokerWireupStrategy)(UnityBuildStage.Initialization)
  End Sub

  Public ReadOnly Property Broker() As EventBroker _
         Implements ISimpleEventBrokerConfiguration.Broker 
    Get
      Return _broker
    End Get
  End Property

End Class

private void OnPublisherFiring(Object sender, EventArgs e)
{
  foreach(EventHandler subscriber in subscribers)
  {
    subscriber(sender, e);
  }
}

Private Sub OnPublisherFiring(sender As Object, e As EventArgs)
  For Each subscriber As EventHandler in _subscribers
    subscriber.Invoke(sender, e)
  Next
End Sub

IUnityContainer container = new UnityContainer()
           .AddNewExtension<SimpleEventBrokerExtension>()
           .RegisterType<ILogger, TraceLogger>()
           .RegisterType<IStoplightTimer, RealTimeTimer>();

Dim container As IUnityContainer = New UnityContainer() _
           .AddNewExtension(Of SimpleEventBrokerExtension)() _
           .RegisterType(Of ILogger, TraceLogger)() _
           .RegisterType(Of IStoplightTimer, RealTimeTimer)()

• RealTimeTimer类发布TimerTick 事件,该事件在计数器变成零的时候产生这个事件,StoplightSchedule 类订阅这个事件.在事件处理中,他更新lightTimes 数组中的索引(TimeSpan 数组保存了不同颜色的时间段),并设置交通灯的时间,然后再次重新计时.
• StoplightSchedule类发布ChangeLight 事件,该事件在时间段改变和计数器重新计数之前发生.StoplightPresenter 类是该事件订阅者.在事件处理中,StoplightPresent调用 StopLight 类的Next方法来改变交通等待颜色,并且将信息写入TraceLogger.

[Publishes("TimerTick")]
public event EventHandler Expired;
private void OnTick(Object sender, EventArgs e)
{
  timer.Stop();
  OnExpired(this);
}

<Publishes("TimerTick")> _
Public Event Expired As EventHandler Implements IStoplightTimer.Expired
Private Sub OnTick(sender As Object, e As EventArgs)
  timer.Stop()
  OnExpired(Me)
End Sub

protected virtual void OnExpired(object sender)
{
  EventHandler handlers = Expired;
  if(handlers != null)
  {
    handlers(this, EventArgs.Empty);
  }
}

Protected Overridable Sub OnExpired(ByVal sender As Object)
  Dim handlers As EventHandler = ExpiredEvent
  If Not handlers Is Nothing Then
    RaiseEvent Expired(Me, EventArgs.Empty)
  End If
End Sub

[SubscribesTo("TimerTick")]
public void OnTimerExpired(Object sender, EventArgs e)
{
  EventHandler handlers = ChangeLight;
  if(handlers != null)
  {
    handlers(this, EventArgs.Empty);
  }
  currentLight = ( currentLight + 1 ) % 3;
  timer.Duration = lightTimes[currentLight];
  timer.Start();
}

<SubscribesTo("TimerTick")> _
Public Sub OnTimerExpired(ByVal sender As Object, ByVal e As EventArgs)
  Dim handlers As EventHandler = ChangeLightEvent
  If Not handlers Is Nothing Then
    RaiseEvent ChangeLight(Me, EventArgs.Empty)
  End If
  currentLight = ( currentLight + 1 ) Mod 3
  _timer.Duration = lightTimes(currentLight)
  _timer.Start()
End Sub

[Publishes("ChangeLight")]
public event EventHandler ChangeLight;

<Publishes("ChangeLight")> _
Public Event ChangeLight As EventHandler

[SubscribesTo("ChangeLight")]
public void OnScheduledLightChange(Object sender, EventArgs e)
{
  stoplight.Next();
}

<SubscribesTo("ChangeLight")> _
Public Sub OnScheduledLightChange(ByVal sender As Object, ByVal e As EventArgs)
  _stoplight.Next()
End Sub