ControlBuilderAttribute 类

参考

定义

命名空间:: System.Web.UI

程序集:: System.Web.dll

重要

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指定用于在 ASP.NET 分析器内生成自定义控件的 ControlBuilder 类。此类不能被继承。

public ref class ControlBuilderAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Class)]
public sealed class ControlBuilderAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Class)>]
type ControlBuilderAttribute = class
    inherit Attribute

Public NotInheritable Class ControlBuilderAttribute
Inherits Attribute

继承: Object

Attribute
ControlBuilderAttribute

属性: AttributeUsageAttribute

示例

下面的代码示例创建一个自定义的选择列表，该列表用于根据 SelectedIndex 运行时定义的值 Message 显示消息。以下命令行用于生成可执行文件。

vbc /r:System.dll /r:System.Web.dll /r:System.Drawing.dll /t:library /out:myWebAppPath/Bin/vb_MyControlBuilderAtt.dll ControlBuilderAtt.vb

csc /t:library /out:myWebAppPath/Bin/cs_MyControlBuilderAtt.dll ControlBuilderAtt.cs


/* File name: controlBuilderAttribute.cs. */

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

namespace CustomControls

{
  public class MyCS_Item : Control 
  /* Class name: MyCS_Item. 
   * Defines the child control class.
   */
    {

      private String _message;

      public String Message 
      {
        get 
        {
          return _message;
        }
        set 
        {
           _message = value;
        }
     }
    }

    public class CustomParseControlBuilder : ControlBuilder 
    /* Class name: CustomParserControlBuilder.
     * Defines the functions and data to be used in building custom controls. 
     * This class is referenced using the ControlBuilderAttribute class. See class below.
     */
    {
      [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
      public override Type GetChildControlType(String tagName, IDictionary attributes) 
      {
        if (String.Compare(tagName, "customitem", true) == 0) 
        {
           return typeof(MyCS_Item);
        }
        return null;
      }
    }

    [ 
       ControlBuilderAttribute(typeof(CustomParseControlBuilder)) 
    ]
    public class MyCS_CustomParse : Control 
    /* Class name: MyCS_CustomParse.
     * Performs custom parsing of a MyCS_CustomParse control type 
     * child control. 
     * If the child control is of the allowed type, it is added to an 
     * array list. This list is accessed, using the container control attribute 
     * SelectedIndex, to obtain the related child control Message attribute to be displayed.
     */
    {

       private ArrayList _items         = new ArrayList();
       private int       _selectedIndex = 0;

       public int SelectedIndex 
       { 
           get 
           {
              return _selectedIndex;
           }
           set 
           {
              _selectedIndex = value;
           }
       }

       [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
       protected override void AddParsedSubObject(Object obj) 
       /* Function name: AddParsedSubObject.
        * Updates the array list with the allowed child objects.
        * This function is called during the parsing of the child controls and 
        * after the GetChildControlType function defined in the associated control 
        * builder class.
        */
       {
          if (obj is MyCS_Item) 
         {
              _items.Add(obj);
           }
       }

       [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
       protected override void Render(HtmlTextWriter output) 
       /* Function name: Render.
        * Establishes the rules to render the built control. In this case, a message is
        * rendered that is a function of the parent control SelectedIndex attribute and 
        * the related child Message attribute.
        */
       {
          if (SelectedIndex < _items.Count) 
         {
              output.Write("<span style='background-color:aqua; color:red; font:8pt tahoma, verdana;'><b>" +
              ((MyCS_Item) _items[SelectedIndex]).Message + "</b></span>" );
         }
       }
    }    
}


'File name: controlBuilderAttribute.vb.

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



Namespace CustomControls

Public Class MyVB_Item: Inherits Control
      
      Private _message As String
      
      Public Property Message() As String
         Get
            Return _message
         End Get
         Set
            _message = value
         End Set
      End Property
   End Class
   
   Public Class VB_CustomParseControlBuilder: Inherits ControlBuilder

      <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")>  _
      Public Overrides Function GetChildControlType(TagName As String, attributes As IDictionary) As Type
          If (TagName = "customitem")  Then
            Return GetType(CustomControls.MyVB_Item)
         End If
         Return Nothing
      End Function 'GetChildControlType
   End Class
   
   <ControlBuilderAttribute(GetType(VB_CustomParseControlBuilder))>  Public Class MyVB_CustomParse: Inherits Control
      
      Private _items As New ArrayList
      Private _selectedIndex As Integer = 0
      
      
      Public Property SelectedIndex() As Integer
         Get
            Return _selectedIndex
         End Get
         Set
            _selectedIndex = value
         End Set
      End Property
      
      <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
      Protected Overrides Sub AddParsedSubObject(obj As Object)
         If TypeOf obj Is MyVB_Item Then
            _items.Add(obj)
         End If
      End Sub
      
      <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
      Protected Overrides Sub Render(output As HtmlTextWriter)        
        output.Write(("<span style='background-color:aqua; color:red; font:8pt tahoma, verdana;'><b>" + CType(_items(SelectedIndex), MyVB_Item).Message + "</b></span>"))
      End Sub
   End Class
   
End Namespace 'CustomControls

以下示例使用上面定义的自定义控件。具体而言，它会在运行时分配 SelectedIndex 和 Message 值来确定要呈现的消息。请注意，指令中显示的 Register 值反映了上一个命令行。

<%@ Register TagPrefix="custom" Assembly="myControlBuilderAtt" Namespace="CustomControls" %>  
 <h4>Using ControlBuilderAttribute Class<h4>  
 <form runat="server">  
  <custom:MyVB_CustomParse SelectedIndex="3" runat=server>  
  <customitem Message="Visual Basic version. Item One selected"/>  
  <customitem Message="Visual Basic version. Item Two selected"/>  
  <customitem Message="Visual Basic version. Item Three selected"/>  
  <customitem Message="Visual Basic version. Item Four selected"/>  
  </custom:MyVB_CustomParse>  
 </form>

<%@ Register TagPrefix="custom" Assembly="myControlBuilderAtt" Namespace="CustomControls" %>  
 <h4>Using ControlBuilderAttribute Class<h4>  
 <form runat="server">  
  <custom:MyCS_CustomParse SelectedIndex="2" runat=server>  
  <customitem Message="C# version. Item One selected"/>  
  <customitem Message="C# version. Item Two selected"/>  
  <customitem Message="C# version. Item Three selected"/>  
  <customitem Message="C# version. Item Four selected"/>  
  </custom:MyCS_CustomParse>  
 </form>

注解

此属性指定要用于创建自定义控件的生成器 Type ，如以下代码所示：

[ControlBuilderAttribute(typeof(ControlBuilderType))]

构造函数

ControlBuilderAttribute(Type)

为自定义控件指定控件生成器。

字段

Default

指定新 ControlBuilderAttribute 对象。默认情况下，新对象设置为空。此字段为只读。

属性

BuilderType	获取与此特性关联的控件的 Type。此属性为只读。
TypeId	在派生类中实现时，获取此 Attribute 的唯一标识符。 (继承自 Attribute)

方法

Equals(Object)	获取一个值，该值指示当前的 ControlBuilderAttribute 是否与指定对象相同。
GetHashCode()	返回 ControlBuilderAttribute 对象的哈希代码。
GetType()	获取当前实例的 Type。 (继承自 Object)
IsDefaultAttribute()	确定当前控件生成器是否为默认生成器。
Match(Object)	当在派生类中重写时，返回一个指示此实例是否等于指定对象的值。 (继承自 Attribute)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
ToString()	返回表示当前对象的字符串。 (继承自 Object)

显式接口实现

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)	将一组名称映射为对应的一组调度标识符。 (继承自 Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)	检索对象的类型信息，然后可以使用该信息获取接口的类型信息。 (继承自 Attribute)
_Attribute.GetTypeInfoCount(UInt32)	检索对象提供的类型信息接口的数量（0 或 1）。 (继承自 Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)	提供对某一对象公开的属性和方法的访问。 (继承自 Attribute)

适用于

ControlBuilderAttribute 类

定义

示例

注解

构造函数

字段

属性

方法

显式接口实现

适用于

另请参阅

其他资源