在自定义任务中引发和定义事件

创建自定义事件

自定义任务开发人员可通过在其 InitializeTask 方法的重写实现中创建新的 EventInfo 来定义新的自定义事件。创建 EventInfo 后，可使用 Add 方法将其添加到 EventInfos 集合。Add 方法的方法签名如下所示：

public void Add(string eventName, string description, bool allowEventHandlers, string[] parameterNames, TypeCode[] parameterTypes, string[] parameterDescriptions);

下面的代码示例演示自定义任务的 InitializeTask 方法，在该自定义任务中，创建了两个自定义事件并设置了其属性。然后，将新事件添加到 EventInfos 集合。

第一个自定义事件的 eventName 为“OnBeforeIncrement”，description 为“Fires after the initial value is updated”。下一个参数为 true 值，指示此事件应允许创建用于处理事件的事件处理程序容器。事件处理程序是一个可向任务提供包和服务中的结构的容器，像其他诸如包、序列、ForLoop 和 ForEachLoop 的其他容器一样。如果 allowEventHandlers 参数为 true，则将创建事件的 DtsEventHandler 对象。为事件定义的所有参数现在均可在 DtsEventHandler 的变量集合中用于 DtsEventHandler。

public override void InitializeTask(Connections connections,
   VariableDispenser variables, IDTSInfoEvents events,
   IDTSLogging log, EventInfos eventInfos,
   LogEntryInfos logEntryInfos, ObjectReferenceTracker refTracker)
{
    this.eventInfos = eventInfos;
    string[] paramNames = new string[1];
    TypeCode[] paramTypes = new TypeCode[1]{TypeCode.Int32};
    string[] paramDescriptions = new string[1];

    paramNames[0] = "InitialValue";
    paramDescriptions[0] = "The value before it is incremented.";

    this.eventInfos.Add("OnBeforeIncrement", 
      "Fires before the task increments the value.",
      true,paramNames,paramTypes,paramDescriptions);
    this.onBeforeIncrement = this.eventInfos["OnBeforeIncrement"];

    paramDescriptions[0] = "The value after it has been incremented.";
    this.eventInfos.Add("OnAfterIncrement",
      "Fires after the initial value is updated.",
      true,paramNames, paramTypes,paramDescriptions);
    this.onAfterIncrement = this.eventInfos["OnAfterIncrement"];
}

Public Overrides Sub InitializeTask(ByVal connections As Connections, _
ByVal variables As VariableDispenser, ByVal events As IDTSInfoEvents, _
ByVal log As IDTSLogging, ByVal eventInfos As EventInfos, _
ByVal logEntryInfos As LogEntryInfos, ByVal refTracker As ObjectReferenceTracker) 

    Dim paramNames(0) As String
    Dim paramTypes(0) As TypeCode = {TypeCode.Int32}
    Dim paramDescriptions(0) As String

    Me.eventInfos = eventInfos

    paramNames(0) = "InitialValue"
    paramDescriptions(0) = "The value before it is incremented."

    Me.eventInfos.Add("OnBeforeIncrement", _
      "Fires before the task increments the value.", _
      True, paramNames, paramTypes, paramDescriptions)
    Me.onBeforeIncrement = Me.eventInfos("OnBeforeIncrement")

    paramDescriptions(0) = "The value after it has been incremented."
    Me.eventInfos.Add("OnAfterIncrement", _
      "Fires after the initial value is updated.", True, _
      paramNames, paramTypes, paramDescriptions)
    Me.onAfterIncrement = Me.eventInfos("OnAfterIncrement")

End Sub

引发自定义事件

通过调用 FireCustomEvent 方法引发自定义事件。下面的代码行引发了一个自定义事件。

componentEvents.FireCustomEvent(this.onBeforeIncrement.Name,
   this.onBeforeIncrement.Description, ref arguments,
   null, ref bFireOnBeforeIncrement);

componentEvents.FireCustomEvent(Me.onBeforeIncrement.Name, _
Me.onBeforeIncrement.Description, arguments, _
Nothing,  bFireOnBeforeIncrement)

示例

下面的示例演示了一个任务，该任务在 InitializeTask 方法中定义了一个自定义事件，再将该自定义事件添加到 EventInfos 集合，然后通过调用 FireCustomEvent 方法在其 Execute 方法中引发该自定义事件。

[DtsTask(DisplayName = "CustomEventTask")]
    public class CustomEventTask : Task
    {
        public override DTSExecResult Execute(Connections connections, 
          VariableDispenser variableDispenser, IDTSComponentEvents componentEvents,
           IDTSLogging log, object transaction)
        {
            bool fireAgain;
            object[] args = new object[1] { "The value of the parameter." };
            componentEvents.FireCustomEvent( "MyCustomEvent", 
              "Firing the custom event.", ref args,
              "CustomEventTask" , ref fireAgain );
            return DTSExecResult.Success;
        }

        public override void InitializeTask(Connections connections,
          VariableDispenser variableDispenser, IDTSInfoEvents events,
          IDTSLogging log, EventInfos eventInfos,
          LogEntryInfos logEntryInfos, ObjectReferenceTracker refTracker)
        {
            string[] names = new string[1] {"Parameter1"};
            TypeCode[] types = new TypeCode[1] {TypeCode.String};
            string[] descriptions = new string[1] {"Parameter description." };

            eventInfos.Add("MyCustomEvent",
             "Fires when my interesting event happens.",
             true, names, types, descriptions);

        }
   }

<DtsTask(DisplayName = "CustomEventTask")> _ 
    Public Class CustomEventTask
     Inherits Task
        Public Overrides Function Execute(ByVal connections As Connections, _
          ByVal variableDispenser As VariableDispenser, _
          ByVal componentEvents As IDTSComponentEvents, _
          ByVal log As IDTSLogging, ByVal transaction As Object) _
          As DTSExecResult

            Dim fireAgain As Boolean
            Dim args() As Object =  New Object(1) {"The value of the parameter."}

            componentEvents.FireCustomEvent("MyCustomEvent", _
              "Firing the custom event.", args, _
              "CustomEventTask" ,  fireAgain)
            Return DTSExecResult.Success
        End Function
 
        Public Overrides  Sub InitializeTask(ByVal connections As Connections, _
          ByVal variableDispenser As VariableDispenser,
          ByVal events As IDTSInfoEvents,
          ByVal log As IDTSLogging, ByVal eventInfos As EventInfos, ByVal logEnTryInfos As LogEnTryInfos, ByVal refTracker As ObjectReferenceTracker)

            Dim names() As String =  New String(1) {"Parameter1"}
            Dim types() As TypeCode =  New TypeCode(1) {TypeCode.String}
            Dim descriptions() As String =  New String(1) {"Parameter description."}

            eventInfos.Add("MyCustomEvent", _
              "Fires when my interesting event happens.", _
              True, names, types, descriptions)

        End Sub

    End Class

请参阅

任务

概念