关于vb.net程序实例的信息

VB.net生成单个实例应用程序

就是只允许启动单一个应用程序的实例, 试图启动第二次时不会产生新的实例,并激活已经启动的实例.

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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中类的实例化

1.不正确

Dim abc As myClass，定义一个可以引用myClass类型对象的变量abc。这个abc变量存在于栈上。

abc=New myClass。New myClass创建myClass实例对象，这个对象存在于托管堆上。然后（同时）让abc引用（指向）这个对象。

abc变量在栈上，而对象在托管堆上。

abc储存的是对象的地址，而不是对象本身。

看下面的代码

Dim a As myClass,b As myClass,c As myClass

a=New myClass

b=a

c=a

整个过程中只创建了一个myClass对象，位于托管堆上。

三个myClass类型的变量a、b、c位于栈上，都指向了这一个myClass对象

2.类的成员分实例成员和静态成员

实例成员必须在实例对象上调用

静态成员可以直接调用，不需要实例对象。

用VB.NET程序编写代码

Delphi代码如下：

procedure TForm1.Button1Click(Sender: TObject);

var

购物总价:Integer;

折扣:Extended;

begin

购物总价:=StrToInt(Edit1.Text);

if 购物总价250 then

begin

折扣:=0;

end

else if 购物总价500 then

begin

折扣:=0.05;

end

else if 购物总价1000 then

begin

折扣:=0.075;

end

else if 购物总价2000 then

begin

折扣:=0.1;

end

{

此段的折扣是多少？

else if 购物总价3000 then

begin

折扣:=0.05;

end

}

else if 购物总价=3000 then

begin

折扣:=0.15;

end;

ShowMessage('您享受的折扣是：'+FloatToStr(折扣)

+' 原价：'+IntToStr(购物总价)

+' 折后总价：'+FloatToStr(购物总价*(1-折扣)));

end;

关于VB.NET进度条的实例

该实例有很多实现方法,下面介绍一种不同的给你:

首先要在窗体中载入以下控件:progressbar(进度条),label(用来实时显示文本提示),两个timer(分别控制进度条进度的增减),然后用以下代码就能实现:

Public Class Form1

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

Timer1.Enabled = True

Timer1.Interval = 500

Timer2.Interval = 500

ProgressBar1.Value = 0

ProgressBar1.Maximum = 100

ProgressBar1.Minimum = 0

End Sub

'上述过程是设置控件的初始值,也可以在属性面板设置

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

ProgressBar1.Value += 1

Label1.Text = "当前完成" ProgressBar1.Value "%"

If (ProgressBar1.Value = 100) Then

Timer1.Enabled = False

Timer2.Enabled = True

End If

End Sub

'timer1用来控制进度的增加

Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick

ProgressBar1.Value -= 1

Label1.Text = "当前完成" ProgressBar1.Value "%"

If (ProgressBar1.Value = 0) Then

Timer1.Enabled = True

Timer2.Enabled = False

End If

End Sub

'time2用来控制进度的减少

End Class

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()

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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关于vb.net程序实例的信息

VB.net生成单个实例应用程序

VB.net实例

VB.net中类的实例化

用VB.NET程序编写代码

关于VB.NET进度条的实例

求vb.net句柄实例，实现操作其他程序窗口。如我给的例子

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