Question

我正在学习C＃，我需要帮助。我的问题：如何知道USB磁盘是否已安装/卸载？我找到了WndProd的答案

    const int WM_DEVICECHANGE           = 0x0219;
    const int DBT_DEVICEARRIVAL         = 0x8000; 
    const int DBT_DEVICEREMOVECOMPLETE  = 0x8004;

    [StructLayout(LayoutKind.Sequential)]
    public struct DEV_BROADCAST_HDR
    {
        public int dbch_size;
        public int dbch_devicetype;
        public int dbch_reserved;
    }

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_DEVICECHANGE)
        {
            int EventCode = m.WParam.ToInt32();
            Log(string.Format("WM_DEVICECHANGE. Код={0}", EventCode));

            switch (EventCode)
            {
                case DBT_DEVICEARRIVAL:
                {
                    Log("Добавление устройства");
                    break;
                }
                case DBT_DEVICEREMOVECOMPLETE:
                {
                    Log("Удаление устройства");
                    break;
                }
            }
        }
        base.WndProc (ref m);

    }

和这个版本

public class WMIReceiveEvent
    {
        public WMIReceiveEvent()
        {
            try
            {
                WqlEventQuery query = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent");

                ManagementEventWatcher watcher = new ManagementEventWatcher(query);
                Console.WriteLine("Waiting for an event...");

                watcher.EventArrived += new EventArrivedEventHandler(HandleEvent);

                // Start listening for events
                watcher.Start();

                // Do something while waiting for events
                System.Threading.Thread.Sleep(20000);

                // Stop listening for events
                //watcher.Stop();
                //return;
            }
            catch (ManagementException err)
            {

            }
        }

        private void HandleEvent(object sender, EventArrivedEventArgs e)
        {
            Console.WriteLine("Win32_DeviceChangeEvent event occurred.   "+ e.NewEvent.ClassPath.ClassName.ToString());
            Console.WriteLine("2_Win32_DeviceChangeEvent event occurred.   " + e.NewEvent.Properties.ToString());
            Console.ReadLine();
        }            

    }

但是我想要没有WinForm的 DBT_DEVICEARRIVAL 和 DBT_DEVICEREMOVECOMPLETE 的版本。因为对于WndProc需要 System.Windows.Form 而Class必须是后继者“：Form ” 对于WMIReceiveEvent而言，这不是我任务的最佳解决方案。

Answer 1

您可以使用NativeWindow代替Form，仍然使用WndProc(ref Message msg)。它实际上是一种看不见的形式，见例：

[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
public class MyMessageHandler : NativeWindow
{
    private event EventHandler<MyEventArgs> messageReceived;
    public event EventHandler<MyEventArgs> MessageReceived
    {
        add
        {
            if (messageReceived == null || !messageReceived.GetInvocationList().Contains(value))
                messageReceived += value;
        }
        remove
        {
            messageReceived -= value;
        }
    }

    public MyMessageHandler()
    {
        var cp = new CreateParams();
        CreateHandle(cp);
    }

    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
    protected override void WndProc(ref Message msg)
    {
        var handler = messageReceived;
        if (handler != null)
            handler(this, new MyEventArgs(msg));

        base.WndProc(ref msg);
    }
}

Answer 2

为此编写一个Console应用程序的问题是它没有消息循环（至少，默认情况下不是;你必须自己编写）。

更简单的解决方案是创建Windows窗体项目，但不要显示任何窗体。您实际上将创建一个不显示任何用户界面的“后台”应用程序。 WinForms应用程序会自动为您提供消息泵，使您可以捕获您感兴趣的消息。

Answer 3

根据您的应用程序的要求，您也可以进行轮询。您构建一个循环来检查所有可能的驱动器号，如

System.IO.Directory.Exists（为驱动器）;

并将其与现有的驱动器号阵列或结构或其他内容进行比较。只要它们不同就创建一个事件。

这将是一个简单的方法，虽然不是很出色的性能。但正如我所说，这取决于你的要求。

监控端口的USB，没有WinForm，只有控制台应用程序

3 个答案: