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我正在使用此处找到的以下类在我的应用程序中全局挂钩键盘组合。

Imports System.Runtime.InteropServices

Public Class KeyboardHook

<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)> _
Private Overloads Shared Function SetWindowsHookEx(ByVal idHook As Integer, ByVal HookProc As KBDLLHookProc, ByVal hInstance As IntPtr, ByVal wParam As Integer) As Integer
End Function
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)> _
Private Overloads Shared Function CallNextHookEx(ByVal idHook As Integer, ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
End Function
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)> _
Private Overloads Shared Function UnhookWindowsHookEx(ByVal idHook As Integer) As Boolean
End Function

<StructLayout(LayoutKind.Sequential)> _
Private Structure KBDLLHOOKSTRUCT
    Public vkCode As UInt32
    Public scanCode As UInt32
    Public flags As KBDLLHOOKSTRUCTFlags
    Public time As UInt32
    Public dwExtraInfo As UIntPtr
End Structure

<Flags()> _
Private Enum KBDLLHOOKSTRUCTFlags As UInt32
    LLKHF_EXTENDED = &H1
    LLKHF_INJECTED = &H10
    LLKHF_ALTDOWN = &H20
    LLKHF_UP = &H80
End Enum

Public Shared Event KeyDown(ByVal Key As Keys)
Public Shared Event KeyUp(ByVal Key As Keys)

Private Const WH_KEYBOARD_LL As Integer = 13
Private Const HC_ACTION As Integer = 0
Private Const WM_KEYDOWN = &H100
Private Const WM_KEYUP = &H101
Private Const WM_SYSKEYDOWN = &H104
Private Const WM_SYSKEYUP = &H105

Private Delegate Function KBDLLHookProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer

Private KBDLLHookProcDelegate As KBDLLHookProc = New KBDLLHookProc(AddressOf KeyboardProc)
Private HHookID As IntPtr = IntPtr.Zero

Private Function KeyboardProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
    If (nCode = HC_ACTION) Then
        Dim struct As KBDLLHOOKSTRUCT
        Select Case wParam
            Case WM_KEYDOWN, WM_SYSKEYDOWN
                RaiseEvent KeyDown(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
            Case WM_KEYUP, WM_SYSKEYUP
                RaiseEvent KeyUp(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
        End Select
    End If
    Return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam)
End Function

Public Sub New()
    HHookID = SetWindowsHookEx(WH_KEYBOARD_LL, KBDLLHookProcDelegate, System.Runtime.InteropServices.Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly.GetModules()(0)).ToInt32, 0)
    If HHookID = IntPtr.Zero Then
        Throw New Exception("Could not set keyboard hook")
    End If
End Sub

Protected Overrides Sub Finalize()
    If Not HHookID = IntPtr.Zero Then
        UnhookWindowsHookEx(HHookID)
    End If
    MyBase.Finalize()
End Sub

End Class

即使应用程序有焦点，它也能很好地工作，但我有问题。我的应用程序正在使用

 My.Computer.Network.UploadFile

在上传过程中，kayboard 笔画停止响应。鼠标没问题。

如何在我的应用程序中进行其他操作时保持键盘处于活动状态？

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1 回答 1

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是的，这是自找麻烦。Windows 只能在您的程序泵送消息循环时调用您的挂钩回调方法。Windows 没有其他可用的机制来调用主线程而不会导致严重的重入问题。

当您的主线程停止执行其他操作（例如上传文件）时，这将停止正常工作。这是 GUI 应用程序的一般要求，其他任务占用主 UI 线程会使用户界面紧张。它停止响应输入并停止绘画。几秒钟后，Windows 窗口管理器介入并用“幽灵窗口”替换您的主窗口，标题栏中显示“无响应”。你的鼻子更难揉搓，因为这现在也停止处理任何键盘输入，Window 不能调用钩子回调。

您需要在另一个线程上执行长时间运行的任务，以便 UI 线程可以保持响应。或者在您正在谈论的特定情况下，请改用 UploadFileAsync() 。

于 2012-04-29T14:19:26.777 回答