Question

我需要检测USB设备更改事件并将更改更新为WPF窗口。这是我的代码。

    public MainWindow()
    {
        InitializeComponent();
        SourceInitialized += (sender, e) =>
        {
            HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
            source.AddHook(WndProc);
        };
    }

    private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        if (msg == 0x219)  // Device Changed
        {
            UpdateSerialPortDict();
        }
        return IntPtr.Zero;
    }

    private void UpdateSerialPortDict()
    {
        System.Text.RegularExpressions.Regex reg = new System.Text.RegularExpressions.Regex(@"^[\S\s]+\((COM([0-9])+)\)$");
        using (ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_PnPEntity"))
        {
            foreach (ManagementObject obj in searcher.Get())
            {
                if ((string)obj["PNPClass"] == "Ports")
                {
                    string key = obj["Name"] as string;
                    var mat = reg.Match(key);
                    if (mat.Success)
                    {
                        var val = mat.Groups[1].Value;
                        _comDictionary.Add(key, val);
                    }
                }
            }
        }
    }

调用searcher.Get()时程序将崩溃。如果我使用Button来触发UpdateSerialPortDict()，它可以正常工作。但我会通过检测设备更改事件自动更新。

Answer 1

尝试使用调度程序：

private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == 0x219)  // Device Changed
    {
        Dispatcher.BeginInvoke(new Action(() => UpdateSerialPortDict()),
            System.Windows.Threading.DispatcherPriority.Background);
    }
    return IntPtr.Zero;
}

C＃WPF ManagementObjectSearcher.Get（）抛出异常

1 个答案: