ObjectDataSourceDisposingEventArgs 類別

參考

定義

命名空間:: System.Web.UI.WebControls

組件:: System.Web.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

提供 ObjectDisposing 控制項的 ObjectDataSource 事件資料。

public ref class ObjectDataSourceDisposingEventArgs : System::ComponentModel::CancelEventArgs

public class ObjectDataSourceDisposingEventArgs : System.ComponentModel.CancelEventArgs

type ObjectDataSourceDisposingEventArgs = class
    inherit CancelEventArgs

Public Class ObjectDataSourceDisposingEventArgs
Inherits CancelEventArgs

繼承: Object

EventArgs

CancelEventArgs
ObjectDataSourceDisposingEventArgs

範例

本節包含兩個程式碼範例。第一個程式碼範例示範如何使用 ObjectDataSource 控制項搭配商務物件和 GridView 控制項來顯示資訊。第二個程式碼範例提供第一個程式碼範例所使用的中介層商務物件。

下列程式碼範例示範如何使用 ObjectDataSource 控制項搭配商務物件和 GridView 控制項來顯示資訊。您可以針對網頁執行的每個資料作業，使用) (成本很高 (的商務物件。使用昂貴物件的其中一種方式可能是建立一次實例，然後快取它以進行後續作業，而不是針對每個資料作業建立和終結它。此範例示範此模式。您可以處理 ObjectCreating 事件，先檢查物件的快取，然後建立實例，只有在尚未快取一個實例時。然後，處理 ObjectDisposing 事件來快取商務物件以供日後使用，而不是終結它。在此範例中 CancelEventArgs.Cancel ，物件的屬性 ObjectDataSourceDisposingEventArgs 會設定為 true ，以指示 ObjectDataSource 不要在實例上呼叫 Dispose 方法。

<%@ Import namespace="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

// Instead of creating and destroying the business object each time, the 
// business object is cached in the ASP.NET Cache.
private void GetEmployeeLogic(object sender, ObjectDataSourceEventArgs e)
{
    // First check to see if an instance of this object already exists in the Cache.
    EmployeeLogic cachedLogic;
    
    cachedLogic = Cache["ExpensiveEmployeeLogicObject"] as EmployeeLogic;
    
    if (null == cachedLogic) {
            cachedLogic = new EmployeeLogic();            
    }
        
    e.ObjectInstance = cachedLogic;     
}

private void ReturnEmployeeLogic(object sender, ObjectDataSourceDisposingEventArgs e)
{    
    // Get the instance of the business object that the ObjectDataSource is working with.
    EmployeeLogic cachedLogic = e.ObjectInstance as EmployeeLogic;        
    
    // Test to determine whether the object already exists in the cache.
    EmployeeLogic temp = Cache["ExpensiveEmployeeLogicObject"] as EmployeeLogic;
    
    if (null == temp) {
        // If it does not yet exist in the Cache, add it.
        Cache.Insert("ExpensiveEmployeeLogicObject", cachedLogic);
    }
    
    // Cancel the event, so that the object will 
    // not be Disposed if it implements IDisposable.
    e.Cancel = true;
}
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"          
          datasourceid="ObjectDataSource1">
        </asp:gridview>

        <asp:objectdatasource 
          id="ObjectDataSource1"
          runat="server"          
          selectmethod="GetCreateTime"          
          typename="Samples.AspNet.CS.EmployeeLogic"
          onobjectcreating="GetEmployeeLogic"
          onobjectdisposing="ReturnEmployeeLogic" >
        </asp:objectdatasource>        

    </form>
  </body>
</html>

<%@ Import namespace="Samples.AspNet.VB" %>
<%@ Page language="vb" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

' Instead of creating and destroying the business object each time, the 
' business object is cached in the ASP.NET Cache.
Sub GetEmployeeLogic(sender As Object, e As ObjectDataSourceEventArgs)

    ' First check to see if an instance of this object already exists in the Cache.
    Dim cachedLogic As EmployeeLogic 
    
    cachedLogic = CType( Cache("ExpensiveEmployeeLogicObject"), EmployeeLogic)
    
    If (cachedLogic Is Nothing) Then
            cachedLogic = New EmployeeLogic            
    End If
        
    e.ObjectInstance = cachedLogic
    
End Sub ' GetEmployeeLogic

Sub ReturnEmployeeLogic(sender As Object, e As ObjectDataSourceDisposingEventArgs)
    
    ' Get the instance of the business object that the ObjectDataSource is working with.
    Dim cachedLogic  As EmployeeLogic  
    cachedLogic = CType( e.ObjectInstance, EmployeeLogic)
    
    ' Test to determine whether the object already exists in the cache.
    Dim temp As EmployeeLogic 
    temp = CType( Cache("ExpensiveEmployeeLogicObject"), EmployeeLogic)
    
    If (temp Is Nothing) Then
        ' If it does not yet exist in the Cache, add it.
        Cache.Insert("ExpensiveEmployeeLogicObject", cachedLogic)
    End If
    
    ' Cancel the event, so that the object will 
    ' not be Disposed if it implements IDisposable.
    e.Cancel = True
End Sub ' ReturnEmployeeLogic
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"          
          datasourceid="ObjectDataSource1">
        </asp:gridview>

        <asp:objectdatasource 
          id="ObjectDataSource1"
          runat="server"          
          selectmethod="GetCreateTime"          
          typename="Samples.AspNet.VB.EmployeeLogic"
          onobjectcreating="GetEmployeeLogic"
          onobjectdisposing="ReturnEmployeeLogic" >
        </asp:objectdatasource>        

    </form>
  </body>
</html>

下列程式碼範例提供上述程式碼範例所使用的中介層商務物件。程式碼範例是由類別所 EmployeeLogic 定義的基本商務物件所組成，此類別是維護狀態並封裝商務邏輯的類別。如需完整的工作範例，您必須將此程式碼編譯為程式庫，然後從 ASP 頁面使用這些類別。

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Web.UI;
using System.Web.UI.WebControls;
  //
  // EmployeeLogic is a stateless business object that encapsulates
  // the operations you can perform on a NorthwindEmployee object.
  //
  public class EmployeeLogic {

    public EmployeeLogic () : this(DateTime.Now) {        
    }
    
    public EmployeeLogic (DateTime creationTime) { 
        _creationTime = creationTime;
    }

    private DateTime _creationTime;
    
    // Returns a collection of NorthwindEmployee objects.
    public ICollection GetCreateTime () {
      ArrayList al = new ArrayList();
      
      // Returns creation time for this example.      
      al.Add("The business object that you are using was created at " + _creationTime);
      
      return al;
    }
  }
}

Imports System.Collections
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB

  Public Class EmployeeLogic
    
    
    Public Sub New() 
        MyClass.New(DateTime.Now)
    
    End Sub
    
    
    Public Sub New(ByVal creationTime As DateTime) 
        _creationTime = creationTime
    
    End Sub
    
    Private _creationTime As DateTime
    
    
    ' Returns a collection of NorthwindEmployee objects.
    Public Function GetCreateTime() As ICollection 
        Dim al As New ArrayList()
        
        ' Returns creation time for this example.      
        al.Add("The business object that you are using was created at " + _creationTime)
        
        Return al
    
    End Function 'GetCreateTime
  End Class
End Namespace ' Samples.AspNet.VB

備註

類別 ObjectDataSourceDisposingEventArgs 用於方法中 OnObjectDisposing ，可在執行使用 ObjectDataSource 控制項和商務物件的任何資料作業之後，但在終結商務物件之前，提供對商務物件實例的存取權。商務物件是使用 ObjectInstance 屬性來存取。藉由新增委派來處理 ObjectDisposing 事件，您可以存取任何公開的商務物件成員，以執行任何最終工作或清除。

OnObjectDisposing如果執行資料作業的方法是 static 方法，則控制項不會呼叫 ObjectDataSource 方法。當方法為靜態時，不會建立任何商務物件實例。

控制項 ObjectDataSource 會公開許多事件，您可以在其生命週期中處理基礎商務物件。下表列出事件和相關聯的 EventArgs 類別和事件處理常式委派。

事件	EventArgs	EventHandler
ObjectCreating. 會在建立商務物件的實例之前立即發生。	ObjectDataSourceEventArgs	ObjectDataSourceObjectEventHandler
ObjectCreated. 會在建立商務物件的實例之後立即發生。	ObjectDataSourceEventArgs	ObjectDataSourceObjectEventHandler
Selecting. 發生在擷取資料之前。	ObjectDataSourceSelectingEventArgs	ObjectDataSourceSelectingEventHandler
Inserting Updating和 Deleting。會在執行插入、更新或刪除作業之前發生。	ObjectDataSourceMethodEventArgs	ObjectDataSourceMethodEventHandler
Selected 在擷取資料之後發生。	ObjectDataSourceStatusEventArgs	ObjectDataSourceStatusEventHandler
Inserted Updated和 Deleted。在插入、更新或刪除作業完成之後發生。	ObjectDataSourceStatusEventArgs	ObjectDataSourceStatusEventHandler
ObjectDisposing. 在終結商務物件之前發生。	ObjectDataSourceDisposingEventArgs	ObjectDataSourceDisposingEventHandler

建構函式

ObjectDataSourceDisposingEventArgs(Object)

使用指定的物件，初始化 ObjectDataSourceDisposingEventArgs 類別的新執行個體。

屬性

Cancel	取得或設定值，這個值表示是否應該取消事件。 (繼承來源 CancelEventArgs)
ObjectInstance	取得物件，表示 ObjectDataSource 控制項用於執行資料作業的商務物件。

方法

Equals(Object)	判斷指定的物件是否等於目前的物件。 (繼承來源 Object)
GetHashCode()	做為預設雜湊函式。 (繼承來源 Object)
GetType()	取得目前執行個體的 Type。 (繼承來源 Object)
MemberwiseClone()	建立目前 Object 的淺層複製。 (繼承來源 Object)
ToString()	傳回代表目前物件的字串。 (繼承來源 Object)

適用於

ObjectDataSourceDisposingEventArgs 類別

定義

範例

備註

建構函式

屬性

方法

適用於

另請參閱

意見反應

其他資源