Question

我正在尝试检测USB设备的插入并使用WinForm桌面C＃应用程序将其删除：

 public Form1()
    {
        InitializeComponent();
        USB();
    }

然后：

private void USB()
{
     WqlEventQuery weqQuery = new WqlEventQuery();
     weqQuery.EventClassName = "__InstanceOperationEvent";
     weqQuery.WithinInterval = new TimeSpan(0, 0, 3);
     weqQuery.Condition = @"TargetInstance ISA 'Win32_DiskDrive'";  
     var m_mewWatcher = new ManagementEventWatcher(weqQuery);
     m_mewWatcher.EventArrived += new EventArrivedEventHandler(m_mewWatcher_EventArrived);
     m_mewWatcher.Start();           
}

和：

static void m_mewWatcher_EventArrived(object sender, EventArrivedEventArgs e)
    {
        bool bUSBEvent = false;
        foreach (PropertyData pdData in e.NewEvent.Properties)
        {
            ManagementBaseObject mbo = (ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value;
           // ManagementBaseObject mbo = (ManagementBaseObject)pdData.Value;
            if (mbo != null)
            {
                foreach (PropertyData pdDataSub in mbo.Properties)
                {
                    if (pdDataSub.Name == "InterfaceType" && pdDataSub.Value.ToString() == "USB")
                    {
                        bUSBEvent = true;
                        break;
                    }
                }

                if (bUSBEvent)
                {
                    if (e.NewEvent.ClassPath.ClassName == "__InstanceCreationEvent")
                    {
                        MessageBox.Show ("USB was plugged in");
                    }
                    else if (e.NewEvent.ClassPath.ClassName == "__InstanceDeletionEvent")
                    {
                        MessageBox.Show("USB was plugged out");
                    }
                }
            }
        }
    }

但是当检测到USB变化时，我遇到了ManagementBaseObject mbo = (ManagementBaseObject)pdData.Value;的异常情况：

“ System.InvalidCastException”类型的异常发生在   Controller.exe，但未在用户代码中处理

其他信息：无法转换类型为'System.UInt64'的对象   键入“ System.Management.ManagementBaseObject”。

编辑：

using System;
using System.Windows.Forms;
using System.Management;

namespace test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            WqlEventQuery query = new WqlEventQuery()
            {
                EventClassName = "__InstanceOperationEvent",
                WithinInterval = new TimeSpan(0, 0, 3),
                Condition = @"TargetInstance ISA 'Win32_DiskDrive'"
            };

            using (ManagementEventWatcher MOWatcher = new ManagementEventWatcher(query))
            {
                MOWatcher.EventArrived += new EventArrivedEventHandler(DeviceInsertedEvent);
                MOWatcher.Start();
            }
        }

        private void DeviceInsertedEvent(object sender, EventArrivedEventArgs e)
        {
            using (ManagementBaseObject MOBbase = (ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value)
            {
                bool DriveArrival = false;
                string EventMessage = string.Empty;
                string oInterfaceType = MOBbase.Properties["InterfaceType"]?.Value.ToString();

                if (e.NewEvent.ClassPath.ClassName.Equals("__InstanceDeletionEvent"))
                {
                    DriveArrival = false;
                    EventMessage = oInterfaceType + " Drive removed";
                }
                else
                {
                    DriveArrival = true;
                    EventMessage = oInterfaceType + " Drive inserted";
                }
                EventMessage += ": " + MOBbase.Properties["Caption"]?.Value.ToString();
                this.BeginInvoke((MethodInvoker)delegate { this.UpdateUI(DriveArrival, EventMessage); });
            }
        }

        private void UpdateUI(bool IsDriveInserted, string message)
        {
            if (IsDriveInserted)
            {
                this.label1.Text = message;
            }             
            else
            {
                this.label1.Text = message;
            }                
        }
    }
}

Answer 1

此处，ManagementEventWatcher在Button.Click()事件中被初始化。当然，您可以在其他地方初始化它。例如在Form.Load()中。

已预订ManagementEventWatcher.EventArrived事件，将委托设置为private void DeviceInsertedEvent()。观看过程是使用ManagementEventWatcher.Start()（MOWatcher.Start();）开始的

通知事件后，EventArrivedEventArgs e.NewEvent。Properties["TargetInstance"].Value将被设置为ManagementBaseObject，它将引用Win32_DiskDrive WMI / CIM类。
阅读文档以了解此类中的可用信息。

UI线程中未引发此事件。要通知主UI界面事件的性质，我们需要在该线程中.invoke（）一个方法。

this.BeginInvoke((MethodInvoker)delegate { this.UpdateUI(DriveArrival, EventMessage); });

在这里，调用private void UpdateUI()方法，将UI更新委托给在UI线程中执行的方法。

更新：
添加了RegisterWindowMessage()来注册QueryCancelAutoPlay，以防止“自动播放”窗口在我们的窗体前弹出，从而夺取焦点。

结果的直观示例：

[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
internal static extern uint RegisterWindowMessage(string lpString);

private uint CancelAutoPlay = 0;

private void button1_Click(object sender, EventArgs e)
{
    WqlEventQuery query = new WqlEventQuery() {
        EventClassName = "__InstanceOperationEvent",
        WithinInterval = new TimeSpan(0, 0, 3),
        Condition = @"TargetInstance ISA 'Win32_DiskDrive'"
    };

    ManagementScope scope = new ManagementScope("root\\CIMV2");
    using (ManagementEventWatcher MOWatcher = new ManagementEventWatcher(query))
    {
        MOWatcher.Options.Timeout = ManagementOptions.InfiniteTimeout;
        MOWatcher.EventArrived += new EventArrivedEventHandler(DeviceChangedEvent);
        MOWatcher.Start();
    }
}

private void DeviceChangedEvent(object sender, EventArrivedEventArgs e)
{
    using (ManagementBaseObject MOBbase = (ManagementBaseObject)e.NewEvent.Properties["TargetInstance"].Value)
    {
        bool DriveArrival = false;
        string EventMessage = string.Empty;
        string oInterfaceType = MOBbase.Properties["InterfaceType"]?.Value.ToString();

        if (e.NewEvent.ClassPath.ClassName.Equals("__InstanceDeletionEvent"))
        {
            DriveArrival = false;
            EventMessage = oInterfaceType + " Drive removed";
        }
        else
        {
            DriveArrival = true;
            EventMessage = oInterfaceType + " Drive inserted";
        }
        EventMessage += ": " + MOBbase.Properties["Caption"]?.Value.ToString();
        this.BeginInvoke((MethodInvoker)delegate { this.UpdateUI(DriveArrival, EventMessage); });
    }
}


private void UpdateUI(bool IsDriveInserted, string message)
{
    if (IsDriveInserted)
        this.lblDeviceArrived.Text = message;
    else
        this.lblDeviceRemoved.Text = message;
}


[SecurityPermission(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)]
protected override void WndProc(ref Message m)
{
    base.WndProc(ref m);

    if (CancelAutoPlay == 0)
        CancelAutoPlay = RegisterWindowMessage("QueryCancelAutoPlay");

    if ((int)m.Msg == CancelAutoPlay) { m.Result = (IntPtr)1; }
}

捕获USB插拔事件System.InvalidCastException

1 个答案: