vb.net简单的实例的简单介绍

VB.net实例

1 生成txt文件。

DimSaveFileDialog1AsNewSaveFileDialog() '创建一个保存对话框

SaveFileDialog1.Filter ="txt files (*.txt)|*.txt" '设置扩展名

IfSaveFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OKThen '如果确定保存

My.Computer.FileSystem.WriteAllText(SaveFileDialog1.Filename, Textbox1.Text,False) '保存文本,False表示不追加文本，直接覆盖其内容

EndIf

原文链接：

vb.net中如何用事件和委托，会C#中的事件和委托，但不知VB.net中的语法，望给个简单的例子熟悉语法。

一委托：此示例演示如何将方法与委托关联然后通过委托调用该方法。

创建委托和匹配过程

创建一个名为 MySubDelegate 的委托。

Delegate Sub MySubDelegate(ByVal x As Integer)

声明一个类，该类包含与该委托具有相同签名的方法。

Class class1

Sub Sub1(ByVal x As Integer)

MsgBox("The value of x is: " CStr(x))

End Sub

End Class

定义一个方法，该方法创建该委托的实例并通过调用内置的 Invoke 方法调用与该委托关联的方法。

Protected Sub DelegateTest()

Dim c1 As New class1

' Create an instance of the delegate.

Dim msd As MySubDelegate = AddressOf c1.Sub1

' Call the method.

msd.Invoke(10)

End Sub

二、事件

下面的示例程序阐释如何在一个类中引发一个事件，然后在另一个类中处理该事件。AlarmClock 类定义公共事件 Alarm，并提供引发该事件的方法。AlarmEventArgs 类派生自 EventArgs，并定义 Alarm 事件特定的数据。WakeMeUp 类定义处理 Alarm 事件的 AlarmRang 方法。AlarmDriver 类一起使用类，将使用 WakeMeUp 的 AlarmRang 方法设置为处理 AlarmClock 的 Alarm 事件。

该示例程序使用事件和委托和引发事件中详细说明的概念。

示例

' EventSample.vb.

'

Option Explicit

Option Strict

Imports System

Imports System.ComponentModel

Imports Microsoft.VisualBasic

Namespace EventSample

' Class that contains the data for

' the alarm event. Derives from System.EventArgs.

'

Public Class AlarmEventArgs

Inherits EventArgs

Private _snoozePressed As Boolean

Private nrings As Integer

'Constructor.

'

Public Sub New(snoozePressed As Boolean, nrings As Integer)

Me._snoozePressed = snoozePressed

Me.nrings = nrings

End Sub

' The NumRings property returns the number of rings

' that the alarm clock has sounded when the alarm event

' is generated.

'

Public ReadOnly Property NumRings() As Integer

Get

Return nrings

End Get

End Property

' The SnoozePressed property indicates whether the snooze

' button is pressed on the alarm when the alarm event is generated.

'

Public ReadOnly Property SnoozePressed() As Boolean

Get

Return _snoozePressed

End Get

End Property

' The AlarmText property that contains the wake-up message.

'

Public ReadOnly Property AlarmText() As String

Get

If _snoozePressed Then

Return "Wake Up!!! Snooze time is over."

Else

Return "Wake Up!"

End If

End Get

End Property

End Class

' Delegate declaration.

'

Public Delegate Sub AlarmEventHandler(sender As Object, _

e As AlarmEventArgs)

' The Alarm class that raises the alarm event.

'

Public Class AlarmClock

Private _snoozePressed As Boolean = False

Private nrings As Integer = 0

Private stopFlag As Boolean = False

' The Stop property indicates whether the

' alarm should be turned off.

'

Public Property [Stop]() As Boolean

Get

Return stopFlag

End Get

Set

stopFlag = value

End Set

End Property

' The SnoozePressed property indicates whether the snooze

' button is pressed on the alarm when the alarm event is generated.

'

Public Property SnoozePressed() As Boolean

Get

Return _snoozePressed

End Get

Set

_snoozePressed = value

End Set

End Property

' The event member that is of type AlarmEventHandler.

'

Public Event Alarm As AlarmEventHandler

' The protected OnAlarm method raises the event by invoking

' the delegates. The sender is always this, the current instance

' of the class.

'

Protected Overridable Sub OnAlarm(e As AlarmEventArgs)

RaiseEvent Alarm(Me, e)

End Sub

' This alarm clock does not have

' a user interface.

' To simulate the alarm mechanism it has a loop

' that raises the alarm event at every iteration

' with a time delay of 300 milliseconds,

' if snooze is not pressed. If snooze is pressed,

' the time delay is 1000 milliseconds.

'

Public Sub Start()

Do

nrings += 1

If stopFlag Then

Exit Do

Else

If _snoozePressed Then

System.Threading.Thread.Sleep(1000)

If (True) Then

Dim e As New AlarmEventArgs(_snoozePressed, nrings)

OnAlarm(e)

End If

Else

System.Threading.Thread.Sleep(300)

Dim e As New AlarmEventArgs(_snoozePressed, nrings)

OnAlarm(e)

End If

End If

Loop

End Sub

End Class

' The WakeMeUp class has a method AlarmRang that handles the

' alarm event.

'

Public Class WakeMeUp

Public Sub AlarmRang(sender As Object, e As AlarmEventArgs)

Console.WriteLine((e.AlarmText + ControlChars.Cr))

If Not e.SnoozePressed Then

If e.NumRings Mod 10 = 0 Then

Console.WriteLine(" Let alarm ring? Enter Y")

Console.WriteLine(" Press Snooze? Enter N")

Console.WriteLine(" Stop Alarm? Enter Q")

Dim input As String = Console.ReadLine()

If input.Equals("Y") Or input.Equals("y") Then

Return

Else

If input.Equals("N") Or input.Equals("n") Then

CType(sender, AlarmClock).SnoozePressed = True

Return

Else

CType(sender, AlarmClock).Stop = True

Return

End If

End If

End If

Else

Console.WriteLine(" Let alarm ring? Enter Y")

Console.WriteLine(" Stop Alarm? Enter Q")

Dim input As String = Console.ReadLine()

If input.Equals("Y") Or input.Equals("y") Then

Return

Else

CType(sender, AlarmClock).Stop = True

Return

End If

End If

End Sub

End Class

' The driver class that hooks up the event handling method of

' WakeMeUp to the alarm event of an Alarm object using a delegate.

' In a forms-based application, the driver class is the

' form.

'

Public Class AlarmDriver

Public Shared Sub Main()

' Instantiates the event receiver.

Dim w As New WakeMeUp()

' Instantiates the event source.

Dim clock As New AlarmClock()

' Wires the AlarmRang method to the Alarm event.

AddHandler clock.Alarm, AddressOf w.AlarmRang

clock.Start()

End Sub

End Class

End Namespace

求vb.net句柄实例，实现操作其他程序窗口。如我给的例子

Imports System.Text

Imports System.Runtime.InteropServices

Public Class Form1

    ' 相关API函数声明,注释掉的这里没用到，但是也比较常用吧，这些函数的功能都能搜到。

    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr

    Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As IntPtr, ByVal hWnd2 As IntPtr, ByVal lpsz1 As String, ByVal lpsz2 As String) As IntPtr

    Private Delegate Function EnumChildProc(ByVal hWnd As IntPtr, ByVal lParam As Integer) As Boolean

    Private Declare Function EnumChildWindows Lib "user32.dll" (ByVal hWndParent As IntPtr, ByVal lpEnumFunc As EnumChildProc, ByVal lParam As Integer) As Boolean

    Private Declare Auto Function SendMessage Lib "User32.dll" (ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByVal lParam As String) As Integer

    'Private Declare Function CheckDlgButton Lib "user32" Alias "CheckDLGButtonA" (ByVal hDlg As IntPtr, ByVal nIDButton As IntPtr, ByVal wCheck As Integer) As Integer

    Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hWnd As IntPtr, ByVal lpClassName As StringBuilder, ByVal nMaxCount As Integer) As Integer

    'Private Declare Function GetWindowThreadProcessId Lib "user32" Alias "GetWindowThreadProcessId" (ByVal hwnd As IntPtr, ByVal lpdwProcessId As Long) As Integer

    Private Declare Auto Function GetWindowTextLength Lib "user32" Alias "GetWindowTextLength" (ByVal hwnd As IntPtr) As Integer

    Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As IntPtr, ByVal lpString As StringBuilder, ByVal cch As Integer) As Integer

    ' 相关消息定义，也有没用到的

    Const WM_SETTEXT = HC

    Const WM_GETTEXT = HD

    'Const WM_SETFOCUS = H7

    'Const WM_KILLFOCUS = H8

    'Const WM_CLOSE = H10

    'Const WM_SYSCOMMAND = H112

    'Const SC_CLOSE = HF060

    'Const SC_MINIMIZE = HF020

    Const BM_GETCHECK = HF0

    Const BM_SETCHECK = HF1

    Const BM_GETSTATE = HF2

    Const BM_SETSTATE = HF3

    Const BM_SETSTYLE = HF4

    Const BM_CLICK = HF5

    'Const BM_GETIMAGE = HF6

    'Const BM_SETIMAGE = HF7

    Const BST_UNCHECKED = O0

    Const BST_CHECKED = O1

    Const BST_INDETERMINATE = O2

    ' 储存窗口句柄

    Dim WindowHandle As IntPtr

    ' 储存两个（或者多个）编辑框句柄

    Dim EditHandle As New List(Of IntPtr)

    Dim EditWindowsText As List(Of String)

    ' 储存复选框句柄

    Dim CheckHandle As IntPtr = 0

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Button1_Click(sender, e)

    End Sub

    ' EnumChildWindows 回调函数，该函数名作为API函数EnumChildWindows 的一个参数

    ' 该函数实现了枚举各个子窗口，找出编辑框属性的功能

    Public Function EnumChildProcC(ByVal hwnd As IntPtr, ByVal lParam As Integer) As Boolean

        Dim dwWindowClass As StringBuilder = New StringBuilder(100)

        ' 获得某一个句柄的类名

        GetClassName(hwnd, dwWindowClass, 100)

        If dwWindowClass.ToString.Contains("EDIT") Or dwWindowClass.ToString.Contains("Edit") Then     ' 类名包含EDIT的为编辑框

            EditHandle.Add(hwnd)                        ' 存储该句柄

        End If

        ' 返回 True 一直枚举完

        Return True

    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        WindowHandle = FindWindow(vbNullString, "登陆")

        If WindowHandle.ToInt32 = 0 Then

            MsgBox("未捕获到窗口" + "登陆")

            Return

        End If

        ' 枚举所有主窗口的子窗口（控件），枚举时自动调用回调函数，完成编辑框句柄的获取

        EnumChildWindows(WindowHandle, AddressOf EnumChildProcC, 0)

        ' 寻找复选框

        CheckHandle = FindWindowEx(WindowHandle, IntPtr.Zero, vbNullString, "记住密码")

        Dim str As New StringBuilder

        Dim j As Integer = 0

        ' 对编辑框文本赋值

        For j = 0 To EditHandle.Count - 1

            SendMessage(EditHandle(j), WM_SETTEXT, 0, "Text")

            'GetWindowText(EditHandle(j), str, 20)

            'EditWindowsText.Add(Str.ToString)

            'Str.Clear()

        Next

        If EditHandle.Count = 0 Then

            MsgBox("未找到输入框！")

        End If        

        If CheckHandle.ToInt32  0 Then

            'CheckDlgButton(WindowHandle, id, 1)

            ' 对复选框进行鼠标单击操作

            SendMessage(CheckHandle, BM_CLICK, 0, 0)

            'SendMessage(CheckHandle, BM_SETCHECK, True, 0)

        End If

    End Sub

    

End Class

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