MdbDataFileEditor 类

定义

public ref class MdbDataFileEditor : System::Web::UI::Design::UrlEditor

public class MdbDataFileEditor : System.Web.UI.Design.UrlEditor

type MdbDataFileEditor = class
    inherit UrlEditor

Public Class MdbDataFileEditor
Inherits UrlEditor

继承

Object

UITypeEditor

UrlEditor

MdbDataFileEditor

示例

下面的代码示例演示如何将 类的 MdbDataFileEditor 实例与自定义控件中包含的属性相关联。 在设计图面上编辑控件属性时， MdbDataFileEditor 类提供用户界面，用于选择和编辑属性值的 Access 数据库文件名。

using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Web.UI;
using System.Web.UI.Design;
using System.Web.UI.Design.WebControls;
using System.Web.UI.WebControls;
using System.IO;

namespace ControlDesignerSamples.CS
{
    // Define a simple text control, derived from the 
    // System.Web.UI.WebControls.Label class.
    [
        Designer(typeof(TextControlDesigner))
    ]
    public class SimpleTextControl : Label
    {
        // Define a private member to store the file name value in the control.
        private string _filename = "";
        private string _internalText = "";

        // Define the public MDB data file name property.  Indicate that the
        // property can be edited at design-time with the MdbDataFileEditor class.
        [EditorAttribute(typeof(System.Web.UI.Design.MdbDataFileEditor), 
                         typeof(System.Drawing.Design.UITypeEditor))]
        public string MdbFileName
        {
            get
            {
                return _filename;
            }
            set
            {
                _filename = value;
            }
        }

        // Define a property that returns the timestamp
        // for the selected file.
        public string LastChanged
        {
            get
            {
                if ((_filename != null) && (_filename.Length > 0))
                {
                    if (File.Exists(_filename))
                    {
                        DateTime lastChangedStamp = File.GetLastWriteTime(_filename);
                        return lastChangedStamp.ToLongDateString();
                    }
                }
                return "";
            }
        }

        // Override the control Text property, setting the default
        // text to the LastChanged string value for the selected
        // file name.  If the file name has not been set in the
        // design view, then default to an empty string.
        public override string Text
        {
            get
            {
                if ((_internalText == "") && (LastChanged.Length > 0))
                {
                    // If the internally stored value hasn't been set,
                    // and the file name property has been set,
                    // return the last changed timestamp for the file.
                    _internalText = LastChanged;
                } 
                return _internalText;
            }

            set
            {
                if ((value != null) && (value.Length > 0))
                {
                    _internalText = value;
                }
                else {
                    _internalText = "";
                }
            }
        }
    }
}

Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Web.UI
Imports System.Web.UI.Design
Imports System.Web.UI.Design.WebControls
Imports System.Web.UI.WebControls
Imports System.IO

Namespace ControlDesignerSamples.VB


    ' Define a simple text control, derived from the 
    ' System.Web.UI.WebControls.Label class.

    <Designer(GetType(TextControlDesigner))> _
    Public Class SimpleTextControl
        Inherits Label

        ' Define a private member to store the file name value in the control.
        Private _filename As String = ""
        Private _internalText As String = ""

        ' Define the public MDB data file name property.  Indicate that the
        ' property can be edited at design-time with the MdbDataFileEditor class.
        <EditorAttribute(GetType(System.Web.UI.Design.MdbDataFileEditor), _
                         GetType(System.Drawing.Design.UITypeEditor))> _
        Public Property MdbFileName() As String
            Get
                Return _filename
            End Get

            Set(ByVal value As String)
                _filename = value
            End Set
        End Property

        ' Define a property that returns the timestamp
        ' for the selected file.
        Public ReadOnly Property LastChanged() As String
            Get
                If Not _filename Is Nothing AndAlso _filename.Length > 0 Then
                    If File.Exists(_filename) Then
                        Dim lastChangedStamp As DateTime
                        lastChangedStamp = File.GetLastWriteTime(_filename)
                        Return lastChangedStamp.ToLongDateString()
                    End If
                End If

                Return String.Empty

            End Get

        End Property

        ' Override the control Text property, setting the default
        ' text to the LastChanged string value for the selected
        ' file name.  If the file name has not been set in the
        ' design view, then default to an empty string.
        Public Overrides Property Text() As String
            Get
                If _internalText.Length = 0 And LastChanged.Length > 0 Then
                    ' If the internally stored value hasn't been set,
                    ' and the file name property has been set,
                    ' return the last changed timestamp for the file.

                    _internalText = LastChanged
                End If
                Return _internalText
            End Get

            Set(ByVal value As String)
                If Not value Is Nothing AndAlso value.Length > 0 Then
                    _internalText = value
                Else
                    _internalText = String.Empty
                End If

            End Set
        End Property

    End Class
End Namespace

注解

MdbDataFileEditor在设计时使用 对象来选择和编辑 Microsoft Access 数据库文件的 URL (.mdb) ，然后将该 URL 分配给控件属性。 例如， AccessDataSource 控件在设计时使用 MdbDataFileEditor 类来设置 属性的值 DataFile 。

EditorAttribute使用 特性将 与 属性相关联MdbDataFileEditor。 在设计图面上编辑关联的属性时，设计器宿主将调用 EditValue 方法。 方法 EditValue 使用 BuildUrl 方法，该方法反过来显示用于选择 URL 的用户界面，然后返回用户选择的 URL。 方法 GetEditStyle 指示用户界面的显示样式。

从 MdbDataFileEditor 派生类，为 Access 数据库 URL 属性定义自定义编辑器。 例如，派生类可以重写 EditValue 方法，然后使用自定义 Filter 或 Caption 值调用 BuildUrl 方法。

另请参阅

• UrlEditor
• EditorAttribute
• DataFile