c# - 调用 SendMessage (P/Invoke) 一直崩溃

Question

我必须编写一个与第三方程序通信的应用程序(AOL，对不起。:()

通过大量研究，我找到了一些使用 P/Invoke 来做到这一点的方法，并且在大多数情况下它工作没问题，但它会在随后的试验中崩溃，特别是 SendMessage。我在下面概述了崩溃代码。

所有这些都被移植到 .NET来自旧的、旧的 Visual Basic 文件。它可能已经过时了，如果它不可行，我也能理解 - 我只是希望有比 Visual Basic 4.0 更好的方法来完成这项工作。

[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CloseHandle(IntPtr hObject);

[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

[DllImport("user32.dll", SetLastError = true)]
public 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,
                                         IntPtr windowTitle);

[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr SendMessage(HandleRef hWnd,
                                        UInt32 Msg,
                                        IntPtr wParam,
                                        IntPtr lParam);

[DllImport("user32.dll", EntryPoint="SendMessageW")]
public static extern IntPtr SendMessageByString(HandleRef hWnd,
                                                UInt32 Msg,
                                                IntPtr wParam,
                                                StringBuilder lParam);

[DllImport("user32.dll", CharSet = CharSet.Unicode , EntryPoint = "SendMessageW")]
public static extern IntPtr SendMessageByString(HandleRef hWnd,
                                                UInt32 Msg,
                                                IntPtr wParam,
                                                String lParam);

public IntPtr FindClientWindow()
{
    IntPtr aol = IntPtr.Zero;
    IntPtr mdi = IntPtr.Zero;
    IntPtr child = IntPtr.Zero;
    IntPtr rich = IntPtr.Zero;
    IntPtr aollist = IntPtr.Zero;
    IntPtr aolicon = IntPtr.Zero;
    IntPtr aolstatic = IntPtr.Zero;

    aol = Invoke.FindWindow("AOL Frame25", null);
    mdi = Invoke.FindWindowEx(aol, IntPtr.Zero, "MDIClient", null);
    child = Invoke.FindWindowEx(mdi, IntPtr.Zero, "AOL Child", null);
    rich = Invoke.FindWindowEx(child, IntPtr.Zero, "RICHCNTL", null);
    aollist = Invoke.FindWindowEx(child, IntPtr.Zero, "_AOL_Listbox", null);
    aolicon = Invoke.FindWindowEx(child, IntPtr.Zero, "_AOL_Icon", null);
    aolstatic = Invoke.FindWindowEx(child, IntPtr.Zero, "_AOL_Static", null);

    if (rich != IntPtr.Zero &&
        aollist != IntPtr.Zero &&
        aolicon != IntPtr.Zero &&
        aolstatic != IntPtr.Zero)

        return child;
    do
    {
        child = Invoke.FindWindowEx(mdi, child, "AOL Child", null);
        rich = Invoke.FindWindowEx(child, IntPtr.Zero, "RICHCNTL", null);
        aollist = Invoke.FindWindowEx(child, IntPtr.Zero, "_AOL_Listbox", null);
        aolicon = Invoke.FindWindowEx(child, IntPtr.Zero, "_AOL_Icon", null);
        aolstatic = Invoke.FindWindowEx(child, IntPtr.Zero, "_AOL_Static", null);

        if (rich != IntPtr.Zero &&
            aollist != IntPtr.Zero &&
            aolicon != IntPtr.Zero &&
            aolstatic != IntPtr.Zero)

            return child;
    }
    while (child != IntPtr.Zero)
        ;

    return child;
}

IntPtr room = IntPtr.Zero;
IntPtr child = IntPtr.Zero;
IntPtr length = IntPtr.Zero;
IntPtr roomHandle = IntPtr.Zero;

child = FindClientWindow();
room = FindChildByClass(child, "RICHCNTLREADONLY");

HandleRef n = new HandleRef(IntPtr.Zero, room);

length = SendMessage(n, 0x000E, IntPtr.Zero, IntPtr.Zero);

// This is the line that keeps crashing on me.
SendMessageByString(n, 0x000D, new IntPtr( length.ToInt32() + 1 ), str);

public IntPtr FindChildByClass(IntPtr parent, string child)
{
    return Invoke.FindWindowEx(parent, IntPtr.Zero, child, null);
}

Answer 1

您正在使用宽字节 SendMessage..ie 用于宽字符，您是否尝试过正常的 Sendmessage.. public static extern int SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam);

我还注意到，就好像您正试图根据 richtextbox 控件的句柄更改值，因此在另一个进程中四处寻找 AOL 的客户端窗口……是否正确？

这可能是问题的根源，直接修改属于不属于您的窗口的控件(您的程序是托管的，修改非托管进程的窗口)......这可以解释它崩溃的原因。你能解释一下十六进制常量的用途吗？

编辑:当您使用 WM_GETTEXTLENGTH 和 WM_GETTEXT 时，它们是 Windows 消息的一部分，用于从控件中检索文本长度和实际文本。如果你看here看看 pinvoke.net 对它们有什么看法。当您使用 WM_GETTEXTLENGTH 和 WM_GETTEXT 发出“SendMessage”时，您是在告诉 Windows -“嘿，给我获取我提供的关联句柄中文本的长度你在参数 n 中。我刚刚想到，值得一试......我会摆脱那些 SendMessage pinvokes 并只使用这个......

[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, StringBuilder lParam);
//If you use '[Out] StringBuilder', initialize the string builder with proper length first.

child = FindClientWindow();
room = FindChildByClass(child, "RICHCNTLREADONLY");

length = SendMessage(n, 0x000E, IntPtr.Zero, IntPtr.Zero);

StringBuilder sbBuf = new StringBuilder(length);

SendMessageByString(room, 0x000D, new IntPtr( length.ToInt32() + 1 ), out sbBuf); // this is the line that keeps crashing on me.

尝试一下然后回到这里... :)

希望对您有所帮助， 此致， 汤姆。