怎样用VB写多线程 wxh zt

wxhwhmanshan

我们用的第一个API是CreateThread, VB的格式是:

private declare function CreateThread Lib "kernel32" (byval pThreadAttributes as any, byval dwStackSize as long, byval lpStartAddress as long, lpParameter as any, byval dwCreationFlags as long, lpThreadID as long) as long. (从vb API text viewer中拿是最真确的语法)

CreateThread的参数指出你将要创立的县城是什么样子的. CreateThread的返回值是一个县城的handle. 这里是vb的多县城初始化程序:

Public Sub Initialize(lpfnBasFunc as long)
dim dwStackSize as long
dim dwCreationFlags as long
dim lpThreadId as long
dim lpParameter as long
dim myNull as long
myNull = 0& ’create a null pointer
dwStackSize = 0 ’0表示用exe stack size
dwCreationFlags = 4 ’用4表示初始化后先不激活,让别人来激活.
Me.Thread = CreateThread(myNull, dwStackSize, lpfnBasFunc, myNull, dwCreationFlags, lpThreadId)
if Me.Thread = myNull then
Msgbox "create thread failed"
end if
end Sub
下面是两个API用来激活/暂定该线程.

private declare function ResumeThread lib "kernel32"(byval hThread as long)as longprivate declare function SuspendThread lib "kernel32"(byval hThread as long)as long

让我们来用一个变量表示当前县城的状态.
public ThreadStatus as boolean
在vb里,可用property来实现ThreadStatus的管理.


Public property Let Enabled(byval vNewValue as boolean)
if vNewValue = true and Me.ThreadStatus = false then
ResumeThread Me.Thread
Me.ThreadStatus = True
elseif Me.ThreadStatus = true then
SuspendThread Me.Thread
Me.ThreadStatus = False
endif
end Property

这个简单的类可以用New Object来引用:
’make new thread object
dim myThread as New clsThreads
’创建县城 Foo
myThread.Initialize AddressOf Foo
’激活县城
myThread.Enabled = True

执行后,你可以用PVIEW95.EXE看到你的线程.
你还可以提高你的线程的优先级.
SetThreadPriority ’设优先级GetThreadPriority ’查优先级

你把以上的程序加入timer例子,就会看到两个timer同时运行.
这里要提醒一下. vb5的开发环境是单县城的.如果你的程序写错,或中断后试图恢复,往往会出错,有时是GPF错.总之,用vb写多线程可以写出和VC一样快的程序.而且开发容易的多,开发速度也快得多.

抛砖引玉.希望能看到兽经,虎经,鳖经

Lv_Ximing

还是用VB.Net吧，做线程太方便了。