FindWindowEx函数

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当你想控制一个现有的窗口程序时，就需要获取那个程序的窗口句柄。比如有一些黑客软件需要查找到窗口，然后修改窗口的标题。在外挂流行的今天，惊奇地发现它们也可以修改输入窗口的文字。这其中，就需要使用到FindWindowEx函数来定位窗口。下面就来使用这个函数来实现控制Windows里带的计算器程序。打开计算器程序，最小化在状态下面，运行本例子，点击创建按钮后，就可以点按钮，就会把计算器显示在最前面。

函数FindWindowEx声明如下：

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//C#
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className,  string windowTitle);

//VB
DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function FindWindowEx(ByVal parentHandle As IntPtr, _
                      ByVal childAfter As IntPtr, _
                      ByVal lclassName As String, _
                      ByVal windowTitle As String) As IntPtr
End Function

hWndParent是找查窗口的父窗口句柄，如果父窗口是桌面，就可以设置为NULL。

hWndChildAfter是子窗口开始位置。

lpszClass是窗口注册的类型。

lpszWindow是窗口的标题。

调用这个函数的例子如下：

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private IntPtr GetHandleToHorizontalScrollBar(Control parent)
{
    // Locals
    IntPtr childHandle;
    string appDomainHexedHash;

    // Get the hexadecimal value of AppDomain hash code.
    // This value is dynamically appended to the window class name of the child window
    // for .NET Windows Forms.  This name is viewable via the Spy++ tool.
    appDomainHexedHash = AppDomain.CurrentDomain.GetHashCode().ToString("x");

    // Find window handle
    childHandle = FindWindowEx(
        parent.Handle,    // Parent handle
        IntPtr.Zero,    // Child window after which to seek
        "WindowsForms10.SCROLLBAR.app.0." + appDomainHexedHash, // Class name to seek (viewable in the Spy++ tool)
        IntPtr.Zero);    // Window title to seek

    // Return handle
    return childHandle;
}

private string GetUrlFromIE()
{
    IntPtr windowHandle = GetForegroundWindow();
    IntPtr childHandle;
    String strUrlToReturn = "";

    //try to get a handle to IE's toolbar container
    childHandle = FindWindowEx(windowHandle,IntPtr.Zero,"WorkerW",IntPtr.Zero);
    if(childHandle != IntPtr.Zero)
    {
        //get a handle to address bar
        childHandle = FindWindowEx(childHandle,IntPtr.Zero,"ReBarWindow32",IntPtr.Zero);
        if(childHandle != IntPtr.Zero)
        {
            // get a handle to combo boxex
            childHandle = FindWindowEx(childHandle, IntPtr.Zero, "ComboBoxEx32", IntPtr.Zero);
            if(childHandle != IntPtr.Zero)
            {
                // get a handle to combo box
                childHandle = FindWindowEx(childHandle, IntPtr.Zero, "ComboBox", IntPtr.Zero);
                if(childHandle != IntPtr.Zero)
                {
                    //get handle to edit
                    childHandle = FindWindowEx(childHandle, IntPtr.Zero, "Edit", IntPtr.Zero);
                    if (childHandle != IntPtr.Zero)
                    {
                        strUrlToReturn = GetText(childHandle);
                    }
                }
            }
        }
    }
    return strUrlToReturn;
}