学习用户自定义控件
作者：佚名 文章来源：本站原创 更新时间：2007-2-1
以下是我作的一个一个练习，来看vb.net 入门经典。
一、建立一个打开文件的用户控件
在VS2005中，新建一个Window 控件库项目，然后创建一个用户控件。
Imports System.IO
Imports System.ComponentModel
Public Class FileButton
Inherits System.Windows.Forms.Button
'event...
Public Event OpenFile(ByVal sender As Object, ByVal e As OpenFileEventArgs)
'memebers...
Private _buddyBoxName As String
'BuddyBoxName Property
Property BuddyBoxName() As String
Get
Return _buddyBoxName
End Get
Set(ByVal value As String)
_buddyBoxName = value
End Set
End Property
'GetBuddyBox-return the actual TextBox control by looking through
'the parent's Controls property
Public Function GetBuddyBox() As TextBox
'serch name...
Dim searchFor As String = BuddyBoxName.ToLower
'look through each control...
Dim control As Control
For Each control In Parent.Controls
'does the name match?
If control.Name.ToLower = searchFor Then
'we have a match... now,cast the control
'to a text box and return...
Return CType(control, TextBox)
End If
Next
End Function
Private Sub FileButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Click
'try and get the buddy box...
Dim buddyBox As TextBox = GetBuddyBox()
If buddyBox Is Nothing Then
MessageBox.Show("The buddy box could not be found.")
Else
'open the file and return the results...
Dim stream As Stream = File.Open(buddyBox.Text, FileMode.Open)
Dim reader As New StreamReader(stream)
'load the entire file...
Dim contents As String = reader.ReadToEnd
'close the stream and the reader...
stream.Close()
reader.Close()
'do something with the contents
'raise the OpenFile event
Dim args As New OpenFileEventArgs
args.FileName = buddyBox.Text
args.FileText = contents
RaiseEvent OpenFile(Me, args)
End If
End Sub
End Class
二、测试
建立Window工程，加一个窗体，加一个TextBox,再引用上面生成的.dll
然后从选项卡中添加上面的控件FileButton，然后将它拖到画面上。将FileButton的属性BuddyBoxName设为TextBox.name.
加上代码：
Private Sub FileButton1_OpenFile(ByVal sender As System.Object, ByVal e As UserControl.OpenFileEventArgs) Handles FileButton1.OpenFile
MessageBox.Show(e.FileName & Chr(13) & e.FileText)
End Sub
运行，设一下TextBox中的文件路径,单击FileButton1可以打开些文件了。
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