Question

成功运行几分钟后，我的应用程序出现了此错误。

对垃圾收集的类型委托进行了回调＆＃39;！对myApp myApp.globalKeyboardHook + keyboardHookProc ::调用＆＃39;

我知道这是因为垃圾收集器已经杀死了一个对象或其他内容，而我的代码仍在引用同样的东西。

如果是这种情况，GC更可能收集对象或组件。我怎样才能克服这个错误。（有一个参考??）

由于我无法弄清楚代码的哪一部分负责此问题，因此我在此处发布完整的课程。（我想我的其他课程没有问题）

class globalKeyboardHook
    {
        public delegate int keyboardHookProc(int code, int wParam, ref keyboardHookStruct lParam);

        public struct keyboardHookStruct
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;
        }

        IntPtr hInstance;
        const int WH_KEYBOARD_LL = 13;
        const int WM_KEYDOWN = 0x100;
        const int WM_SYSKEYDOWN = 0x104;

        public List<Keys> HookedKeys = new List<Keys>();
        IntPtr hhook = IntPtr.Zero;

        // Events
        public event KeyEventHandler KeyDown;

        public globalKeyboardHook()
        {
            hook();
        }

        ~globalKeyboardHook()
        {
            unhook();
        }

        public void hook()
        {
            hInstance = LoadLibrary("User32");
            hhook = SetWindowsHookEx(WH_KEYBOARD_LL, hookProc, hInstance, 0);
        }

        public void unhook()
        {
            UnhookWindowsHookEx(hhook);
        }

        public int hookProc(int code, int wParam, ref keyboardHookStruct lParam)
        {
            if (code >= 0)
            {
                Keys key = (Keys)lParam.vkCode;
                if (1 == 1)
                {
                    KeyEventArgs kea = new KeyEventArgs(key);
                    if ((wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN) && (KeyDown != null))
                    {
                        KeyDown(this, kea);
                    }
                    if (kea.Handled)
                        return 1;
                }
            }
            return CallNextHookEx(hhook, code, wParam, ref lParam);
        }


        // DLL imports

        [DllImport("user32.dll")]
        static extern IntPtr SetWindowsHookEx(int idHook, keyboardHookProc callback, IntPtr hInstance, uint threadId);

        [DllImport("user32.dll")]
        static extern bool UnhookWindowsHookEx(IntPtr hInstance);

        [DllImport("user32.dll")]
        static extern int CallNextHookEx(IntPtr idHook, int nCode, int wParam, ref keyboardHookStruct lParam);

        [DllImport("kernel32.dll")]
        static extern IntPtr LoadLibrary(string lpFileName);

    }
}

Answer 1

    hhook = SetWindowsHookEx(WH_KEYBOARD_LL, hookProc, hInstance, 0);

您确实无法找到收集的项目，但在您的计划中无法看到。 C＃语言在这里有点太友好了。您依靠其语法糖自动为hookProc创建委托对象。此代码编译为：

    keyboardHookProc $unspeakable = new keyboardHookProc(hookProc);
    hhook = SetWindowsHookEx(WH_KEYBOARD_LL, $unspeakable, hInstance, 0);

pinvoke中存在一个问题，垃圾收集器不知道$ unspeakable委托对象实际上是由本机代码使用的。它只能看到对象的托管引用。所以它会在gen＃0垃圾收集发生时立即收集对象。当Windows进行钩子回调时，Kaboom。

由您来确保无法收集此委托对象。使用GCHandle.Alloc（）。或者简单的方法，明确地将它存储在变量中。这里没问题，因为你让终结器破坏了钩子：

    IntPtr hhook = IntPtr.Zero;
    keyboardHookProc callback;

    public void hook()
    {
        if (callback != null) throw new InvalidOperationException("Hook already installed");
        if (hInstance == IntPtr.Zero) hInstance = LoadLibrary("User32");
        callback = new keyboardHookProc(hookProc);
        hhook = SetWindowsHookEx(WH_KEYBOARD_LL, callback, hInstance, 0);
    }

    public void unhook()
    {
        UnhookWindowsHookEx(hhook);
        callback = null;
    }

错误：CallbackOnCollectedDelegate - 如何查找确切收集的项目？

1 个答案: