EmptyControlCollection 类

定义

public ref class EmptyControlCollection : System::Web::UI::ControlCollection

public class EmptyControlCollection : System.Web.UI.ControlCollection

type EmptyControlCollection = class
    inherit ControlCollection

Public Class EmptyControlCollection
Inherits ControlCollection

继承

Object

ControlCollection

EmptyControlCollection

示例

/* File name: emptyControlCollection.cs. */

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;

namespace CustomControls
{

  // Defines a simple custom control.
  public class MyCS_EmptyControl : Control
  {
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
    protected override ControlCollection CreateControlCollection() 
    /*
     * Function Name: CreateControlCollection.
     * Denies the creation of any child control by creating an empty collection.
     * Generates an exception if an attempt to create a child control is made.
     */
     {
       return new EmptyControlCollection(this);
     }
     
     [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
     protected override void CreateChildControls()
     /*
      * Function Name: CreateChildControls.
      * Populates the child control collection (Controls). 
      * Note: This function will cause an exception because the control does not allow 
      * child controls.
      */
      {
        // Create a literal control to contain the header and add it to the collection.
        LiteralControl text;
        text = new LiteralControl("<h5>Composite Controls</h5>");
        Controls.Add(text);
      }
   }
}

' File name: emptyControlCollection.vb.

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


Namespace CustomControls 

  Public Class MyVB_EmptyControl 
    Inherits Control
    
    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
    Protected Overrides Function CreateControlCollection() As ControlCollection
    ' Function Name: CreateControlCollection.
    ' Denies the creation of any child control by creating an empty collection.
    ' Generates an exception if an attempt to create a child control is made.
      Return New EmptyControlCollection(Me)
    End Function 
    
    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _  
    Protected Overrides Sub CreateChildControls()
    ' Sub Name: CreateChildControls.
    ' Populates the child control collection (Controls). 
    ' Note: This function will cause an exception because the control does not allow 
    ' child controls.
      Dim text As LiteralControl
      text = New LiteralControl("<h5>Composite Controls</h5>")
      Controls.Add(text)
    End Sub 
  End Class 

End Namespace

注解

如果要定义不允许子控件的自定义控件，则使用此类。