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用Visual Basic创建多线程应用程序

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有时候我们做程序时有这样的需求：有一个需要运行时间很长的循环

作者：chenyu5188 来源：BLOG 2007年10月14日

关键字：

代码如下

　　窗体中的代码：

Option Explicit

'开始

Private Sub Command1_Click()

　On Error Resume Next

　With myThreadleft
　　.Initialize AddressOf Fillleft '传递过程地址给线程
　　.ThreadEnabled = True
　End With

　With myThreadright
　　.Initialize AddressOf Fillright
　　.ThreadEnabled = True
　End With

　With myThreadbottom
　　.Initialize AddressOf Fillbottom
　　.ThreadEnabled = True
　End With

　MsgBox "多线程正在运行...，看看图片框控件的变色效果！", 64, "信息"

　'终止线程运行

　Set myThreadleft = Nothing
　Set myThreadright = Nothing
　Set myThreadbottom = Nothing

End Sub

'结束

Private Sub Command2_Click()
　Unload Me
End Sub

模块中的代码：

Option Explicit

'时间计数API

Private Declare Function GetTickCount Lib "kernel32" () As Long

'声明cls_thread类的对象变量
Public myThreadleft As New cls_thread, myThreadright As New cls_thread, myThreadbottom As New cls_thread

Sub Main()
　Load Form1
　Form1.Show
End Sub

Public Sub Fillleft()
　Static Bkgcolor As Long
　Dim LongTick As Long, Longcounter As Long
　On Error Resume Next
　For Longcounter = 0 To 3000
　　DoEvents
　　Bkgcolor = Longcounter Mod 256
　　Form1.Picture1.BackColor = RGB(Bkgcolor, 0, 0)
　　LongTick = GetTickCount
　　While GetTickCount - LongTick < 10 '延时10毫秒,下同
　　Wend
　Next
　Set myThreadleft = Nothing '如果循环结束则终止当前线程运行，下同
End Sub

Public Sub Fillright()
　Static Bkgcolor As Long
　Dim LongTickValue As Long, Longcounter As Long
　On Error Resume Next
　For Longcounter = 0 To 3000
　　DoEvents
　　Bkgcolor = Longcounter Mod 256
　　Form1.Picture2.BackColor = RGB(0, Bkgcolor, 0)
　　LongTickValue = GetTickCount
　　While GetTickCount - LongTickValue < 10
　　Wend
　Next
　Set myThreadright = Nothing
End Sub

Public Sub Fillbottom()
　Static Bkgcolor As Long
　Dim LongTick As Long, Longcounter As Long
　On Error Resume Next
　For Longcounter = 0 To 3000
　　DoEvents
　　Bkgcolor = Longcounter Mod 256
　　Form1.Picture3.BackColor = RGB(0, 0, Bkgcolor)
　　LongTick = GetTickCount
　　While GetTickCount - LongTick < 10
　　Wend
　Next
　Set myThreadright = Nothing
End Sub

类模块中的代码：

'功能：创建多线程类，用于初始化线程。类名：cls_Thread

'参数：LongPointFunction 用于接收主调过程传递过来的函数地址值

'调用方法：1.声明线程类对象变量 Dim mythread as cls_Thread

' 2.调用形式：With mythread

' .Initialize AddressOf 自定义过程或函数名 '(初始化线程) .

' .ThreadEnabled = True '(设置线程是否激活)

' End With

' 3.终止调用： Set mythread = Nothing

' Crate By : 陈宇 On 2004.5.10 Copyright(C).Ldt By CY-soft 2001--2004

' Email:4y4ycoco@163.com　　　　　　　　　　

' Test On： VB6.0+Win98 AND VB6.0+WinXP It's Pass ！

Option Explicit

'创建线程API

'此API经过改造，lpThreadAttributes改为Any型，lpStartAddress改为传值引用：

'因为函数的入口地址由形参变量传递，如果用传址那将传递形参变量的地址而不是函数的入口地址

Private Declare Function CreateThread Lib "kernel32" (ByVal lpThreadAttributes As Any, ByVal dwStackSize As Long, ByVal lpStartAddress As Long, lpParameter As Any, ByVal dwCreationFlags As Long, LpthreadId As Long) As Long

'终止线程API

Private Declare Function TerminateThread Lib "kernel32" (ByVal hThread As Long, ByVal dwExitCode As Long) As Long

'激活线程API

Private Declare Function ResumeThread Lib "kernel32" (ByVal hThread As Long) As Long

'挂起线程API

Private Declare Function SuspendThread Lib "kernel32" (ByVal hThread As Long) As Long
Private Const CREATE_SUSPENDED = &H4 '线程挂起常量

'自定义线程结构类型

Private Type udtThread
　Handle As Long
　Enabled As Boolean
End Type

Private meTheard As udtThread

'初始化线程
Public Sub Initialize(ByVal LongPointFunction As Long)

　Dim LongStackSize As Long, LongCreationFlags As Long, LpthreadId As Long, LongNull As Long
　On Error Resume Next
　LongNull = 0
　LongStackSize = 0
　LongCreationFlags = CREATE_SUSPENDED '创建线程后先挂起，由程序激活线程
　'创建线程并返线程句柄
　meTheard.Handle = CreateThread(LongNull, LongStackSize, ByVal LongPointFunction, LongNull, LongCreationFlags, LpthreadId)

　If meTheard.Handle = LongNull Then
　　MsgBox "线程创建失败！", 48, "错误"
　End If
End Sub

'获取线程是否激活属性

Public Property Get ThreadEnabled() As Boolean
　On Error Resume Next
　Enabled = meTheard.Enabled
End Property

'设置线程是否激活属性

Public Property Let ThreadEnabled(ByVal Newvalue As Boolean)
　On Error Resume Next
　'若激活线程（Newvalue为真）设为TRUE且此线程原来没有激活时激活此线程

　If Newvalue And (Not meTheard.Enabled) 　Then
　　ResumeThread meTheard.Handle
　　meTheard.Enabled = True
　Else '若激活线程（Newvalue为真）且此线程原来已激活则挂起此线程
　　If meTheard.Enabled Then
　　　SuspendThread meTheard.Handle
　　　meTheard.Enabled = False
　　End If
　End If
End Property

'终止线程事件

Private Sub Class_Terminate()
　On Error Resume Next
　Call TerminateThread(meTheard.Handle, 0)
End Sub

　　总结：

　　本程序的缺点是程序运行时CPU占用率高。

　　至此全部源代码结束，在实例的基础上可以根据个人需要做出不同的多线程应用程序，可以用此类模块创建ActiveX DLL，然后引用这个DLL来进行调用。

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