在自定义任务中引发和定义事件
Integration Services 运行时引擎提供了一个事件集合，该集合可在任务验证和执行时提供任务进度的状态。IDTSComponentEvents 接口用于定义这些事件，并且该接口可作为 Validate 和 Execute 方法的参数提供给任务。
此外，还有另一组在 IDTSEvents 接口中定义的事件，TaskHost 可代表任务引发这些事件。TaskHost 将引发在验证和执行之前或之后发生的事件，而任务则引发在执行和验证期间发生的事件。
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
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