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利用windows api获得系统高级功能
vb无疑是最先进的编程工具之一，但在涉及windows 32位系统的核心编程方面——譬如一些高级功能的实现上，它仍然显得有些力不从心，这需要我们充分利用vb的强大的windows api函数调用能力来弥补。以下代码将向您展示如何利用windows api控制系统托盘（图标）区、开始菜单、任务栏以及禁用/起用ctrl-alt-del、退出网络登录、立即关机、重新启动等系统高级功能。
启动vb6，建立一个标准exe工程，添加14个command按钮，caption属性依次为 “隐藏开始菜单”、“显示开始菜单”、“隐藏系统托盘”、“显示系统托盘”、“禁用 ctrl-alt-del”、“起用 ctrl-alt-del”、“隐藏任务栏”、“显示任务栏”、“立即重新启动”、“关机”、“退出网络登陆”、“显示关机对话框”，调整上述控件到适当位置，双击窗体，写入以下代码：
option explicit
private declare function findwindow lib "user32" alias "findwindowa" (byval lpclassname as string, byval lpwindowname as string) as long
'寻找窗口列表中第一个符合指定条件的顶级窗口
'lpclassname指向包含了窗口类名的空中止（c语言）字串的指针；或设为零，'表示接收任何类
'lpwindowname指向包含了窗口文本（或标签）的空中止（c语言）字串的指针；'或设为零，表示接收任何窗口标题
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private declare function showwindow lib "user32" (byval hwnd as long, byval ncmdshow as long) as long
'控制窗口的可见性
'hwnd窗口句柄，要向这个窗口应用由ncmdshow指定的命令
'ncmdshow为窗口指定可视性方面的一个命令
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private declare function findwindowex lib "user32" alias "findwindowexa" (byval hwnd1 as long, byval hwnd2 as long, byval lpsz1 as string, byval lpsz2 as string) as long
'在窗口列表中寻找与指定条件相符的第一个子窗口
'hwnd1在其中查找子的父窗口
'hwnd2从这个窗口后开始查找。这样便可利用对findwindowex的多次调用找到符合条件的所有子窗口。如设为零，表示从第一个子窗口开始搜索
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private declare function exitwindowsex lib "user32" (byval uflags as long, byval dwreserved as long)
'退出windows，并用特定的选项重新启动
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private declare function systemparametersinfo lib "user32" alias "systemparametersinfoa" (byval uaction as long, byval uparam as long, byref lpvparam as any, byval fuwinini as long) as long
'允许获取和设置数量众多的windows系统参数
'uaction指定要设置的参数
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private const ewx_logoff = 0'中止进程，然后注销
private const ewx_shutdown = 1'关掉系统电源
private const ewx_reboot = 2'重新引导系统
private const ewx_force = 4'强迫中止没有响应的进程
private const spi_screensaverrunning = 97
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private sub command1_click() '隐藏开始菜单
dim handle as long, findclass as long
findclass = findwindow("shell_traywnd", "")
handle = findwindowex(findclass, 0, "button", vbnullstring)
showwindow handle, 0
end sub
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private sub command11_click() '起用 ctrl-alt-del
dim ret as integer
dim pold as boolean
ret = systemparametersinfo(spi_screensaverrunning, true, pold, 0)
end sub
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private sub command12_click() '禁用 ctrl-alt-del
dim ret as integer
dim pold as boolean
ret = systemparametersinfo(spi_screensaverrunning, false, pold, 0)
end sub
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private sub command13_click() '立即重新启动
exitwindowsex ewx_reboot, 0
end sub
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private sub command14_click() '关机
exitwindowsex ewx_shutdown, 0
end sub
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private sub command15_click() '退出网络登陆
exitwindowsex ewx_logoff, 0
end sub
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private sub command16_click() '显示关机对话框
exitwindowsex ewx_force, 0
end sub
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private sub command2_click() '显示开始菜单
dim handle as long, findclass as long
findclass = findwindow("shell_traywnd", "")
handle = findwindowex(findclass, 0, "button", vbnullstring)
showwindow handle, 1
end sub
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private sub command5_click() '隐藏系统托盘
dim findclass as long, handle as long
findclass = findwindow("shell_traywnd", "")
handle = findwindowex(findclass, 0, "traynotifywnd", vbnullstring)
showwindow handle, 0
end sub
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private sub command6_click() '显示系统托盘
dim findclass as long, handle as long
findclass = findwindow("shell_traywnd", "")
handle = findwindowex(findclass, 0, "traynotifywnd", vbnullstring)
showwindow handle, 1
end sub
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private sub command7_click() '显示任务栏
dim findclass as long, findclass2 as long, parent as long, handle as long
findclass = findwindow("shell_traywnd", "")
findclass2 = findwindowex(findclass, 0, "rebarwindow32", vbnullstring)
parent = findwindowex(findclass2, 0, "mstaskswwclass", vbnullstring)
handle = findwindowex(parent, 0, "systabcontrol32", vbnullstring)
showwindow handle, 0
end sub
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private sub command8_click() '隐藏任务栏
dim findclass as long, findclass2 as long, parent as long, handle as long
findclass = findwindow("shell_traywnd", "")
findclass2 = findwindowex(findclass, 0, "rebarwindow32", vbnullstring)
parent = findwindowex(findclass2, 0, "mstaskswwclass", vbnullstring)
handle = findwindowex(parent, 0, "systabcontrol32", vbnullstring)
showwindow handle, 1
end sub
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private sub form_queryunload(cancel as integer, unloadmode as integer)
end
end sub
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本文中的部分api函数及其相应的常数较少用到，希望编程爱好者能够有所借鉴和斧正，如果有问题欢迎与我联系zouhero@china.com。
