.net - 使用 DeviceWatcher 监控 USB 驱动器并检索设备信息？

Question

我是 WinForms 开发人员和我已经知道如何使用 WMI 监控连接或断开连接的 USB，但不久前我发现了 DeviceWatcher现代 Windows 应用程序的类，该类第一次感兴趣，因为似乎是一个非常改进和有效的替代方案，可以替代所有解释如何通过 Internet 监视驱动器的“旧”WMI 代码，但直到昨天(感谢 this post ) 我不知道如何在 WinForms 项目中使用 DeviceWatcher，但现在我在 WinForms 项目中使用 DeviceWatcher。

问题是也许我错了，但我认为这不是我所期望的，只是我找不到任何关于 DeviceWatcher 的文档(只有上面的 MSDN 示例)，我找不到方法检索必要的信息来监视驱动器事件，我试图处理 DeviceWatcher 的所有事件，以便在调试控制台中打印出参数中包含的所有数据，希望能找到可以帮助我的东西......但是不，我非常坚持使用 设备观察者 上课，我无法想象如何进行。

当我连接或断开 USB 时，我只看到两件事，硬件 ID 和“InterfaceEnabled”属性(我不知道这是否决定了设备可用性)，没有什么更有趣的了。

What I have accomplished:

· 检索硬件设备 ID。

What I would like to accomplish:

· 当设备连接、断开和断开时检索设备类型(USB 和其他类型设备的区别)。

· 在设备连接、断开和断开连接时检索设备可用性(我的意思是设备是否可以在其上读取/写入数据)。

· 在设备连接、断开和断开连接时检索设备信函。

· 在设备连接、断开和断开时检索设备标签描述。

The code:

Public Class DeviceWatcher_Test

    Private WithEvents dw As DeviceWatcher = DeviceInformation.CreateWatcher

    ' It's suposed that these properties should exist in the "e.properties" on the "dw_updated" event?, not in my case.
    ' Dim props As String() = {"System.ItemNameDisplay", "System.Devices.ModelName", "System.Devices.Connected"}

    Private Sub Test() Handles MyBase.Load

        dw.Start()

    End Sub

    Private Sub dw_Added(ByVal sender As DeviceWatcher, ByVal e As DeviceInformation) _
    Handles dw.Added

        Dim sb As New System.Text.StringBuilder

        With sb
            .AppendLine("dw_added")
            .AppendLine("********")
            .AppendLine(String.Format("Interface ID.: {0}", e.Id))
            .AppendLine(String.Format("Friendly Name: {0}", e.Name))
            .AppendLine(String.Format("Is Enabled?..: {0}", e.IsEnabled))
        End With

        Debug.WriteLine(sb.ToString)

    End Sub

    Private Sub dw_Removed(ByVal sender As DeviceWatcher, ByVal e As DeviceInformationUpdate) _
    Handles dw.Removed

        Dim sb As New System.Text.StringBuilder

        With sb
            .AppendLine("dw_Removed")
            .AppendLine("**********")
            .AppendLine(String.Format("Interface ID:{0}", e.Id))

            For Each item As KeyValuePair(Of String, Object) In e.Properties
                .AppendLine(String.Format("TKey:{0}, TVal:{1} (TVal Type:{2})",
                                          item.Key, item.Value.ToString, item.Value.GetType.Name))
            Next

        End With

        Debug.WriteLine(sb.ToString)

    End Sub

    Private Sub dw_Updated(ByVal sender As DeviceWatcher, ByVal e As DeviceInformationUpdate) _
    Handles dw.Updated

        Dim sb As New System.Text.StringBuilder

        With sb
            .AppendLine("dw_Updated")
            .AppendLine("**********")
            .AppendLine(String.Format("Interface ID: {0}", e.Id))

            For Each item As KeyValuePair(Of String, Object) In e.Properties

                If item.Key.EndsWith("InterfaceEnabled", StringComparison.OrdinalIgnoreCase) Then
                    Dim Result As Boolean = CBool(item.Value)
                    ' I'm not sure whether the 'Result' value really determines this:
                    .AppendLine(String.Format("The device is accessible?:{0}", CStr(Result)))

                Else
                    .AppendLine(String.Format("TKwy:{0}, TVal:{1} (TVal Type:{2})",
                                              item.Key, item.Value.ToString, item.Value.GetType.Name))

                End If

            Next

        End With

        Debug.WriteLine(sb.ToString)

    End Sub

    Private Sub dw_Stopped(ByVal sender As DeviceWatcher, ByVal e As Object) _
    Handles dw.Stopped

        Dim sb As New System.Text.StringBuilder

        With sb
            .AppendLine("dw_Stopped")
            .AppendLine("**********")
            .AppendLine(String.Format("e:{1} (e Type:{2})",
                                      e.ToString, e.GetType.Name))

        End With

        Debug.WriteLine(sb.ToString)

    End Sub

    Private Sub dw_EnumerationCompleted(ByVal sender As DeviceWatcher, ByVal e As Object) _
    Handles dw.EnumerationCompleted

        If e IsNot Nothing Then

            Dim sb As New System.Text.StringBuilder

            With sb
                .AppendLine("EnumerationCompleted")
                .AppendLine("********************")
                .AppendLine(String.Format("e:{1} (e Type:{2})",
                                          e.ToString, e.GetType.Name))

            End With

            Debug.WriteLine(sb.ToString)

        End If

    End Sub

End Class

Answer 1

这将监视 USB 驱动器的到达和移除，并报告 DriveLetter、卷标和设备序列号。为了您的方便，它引发了 2 个事件:

Public Event DeviceAdded(sender As Object, e As USBWatcherEventArgs)
Public Event DeviceRemoved(sender As Object, e As USBWatcherEventArgs)

这只会监视添加/删除的新驱动器，它不会检测诸如弹出或插入 CD 或将媒体插入读卡器插槽之类的事情。

Imports System.Management

Public Class USBWatcher

    ' alternate method to use one event with an extra
    ' event property to report the action
    'Public Enum WatcherActions
    '    DriveInserted = 1
    '    DriveRemoved = 2
    'End Enum

    ' USB device added/removed args
    Public Class USBWatcherEventArgs
        Inherits EventArgs

        'Public Property WatcherAction As WatcherActions
        Public Property DriveLetter As String
        Public Property VolumeName As String
        Public Property VolumeSerial As String

        Friend Sub New(drv As String, vol As String, ser As String)
            DriveLetter = drv
            VolumeName = vol
            VolumeSerial = ser
            'WatcherAction = act
        End Sub

    End Class

    Private WithEvents Watcher As ManagementEventWatcher

    Public Event DeviceAdded(sender As Object, e As USBWatcherEventArgs)
    Public Event DeviceRemoved(sender As Object, e As USBWatcherEventArgs)

    Private pnpCol As Dictionary(Of String, Management.ManagementObject)

    Public Sub New()

    End Sub

    Public Sub StartWatching()

        ' get USBs currently attached
        pnpCol = GetUSBDevices()

        Dim arriveQuery = New WqlEventQuery("Select * from Win32_DeviceChangeEvent")
        Watcher = New ManagementEventWatcher(arriveQuery)

        ' we are watching you
        Watcher.Start()

    End Sub

    Public Sub StopWatching()
        Watcher.Stop()

    End Sub

    Private Function GetUSBDevices() As Dictionary(Of String,
                        Management.ManagementObject)

        Dim col As New Dictionary(Of String, Management.ManagementObject)

        Dim moSearch As New Management.ManagementObjectSearcher("Select * from Win32_LogicalDisk")
        Dim moReturn As Management.ManagementObjectCollection = moSearch.Get


        For Each mo As Management.ManagementObject In moReturn
            'Console.WriteLine("====")
            'DebugProperties(mo)

            ' some USB external drives report as DriveType 3 (local disk), but are
            ' in fact removable.  So monitor all disk drives.
            If col.ContainsKey(mo("DeviceID").ToString) = False Then
                col.Add(mo("DeviceID").ToString, mo)
            End If

        Next

        Return col
    End Function

    Private inEvent As Boolean = False

    Private Sub arrive_EventArrived(ByVal sender As Object, 
                    ByVal e As System.Management.EventArrivedEventArgs) _
                    Handles Watcher.EventArrived

        If inEvent Then Exit Sub
        inEvent = True

        Dim col As Dictionary(Of String, Management.ManagementObject) = GetUSBDevices()

        Select Case col.Count
            Case Is > pnpCol.Count
                ' device arrived
                ProcessArrival(col)
            Case Is < pnpCol.Count
                ' device removed
                ProcessRemoval(col)
            Case Is = pnpCol.Count
                ' noise...this is a chatty rascal
        End Select

        inEvent = False

    End Sub

    Private Sub ProcessArrival(col As Dictionary(Of String,
               Management.ManagementObject))
        For Each kvp As KeyValuePair(Of String, 
                 Management.ManagementObject) In col
            If pnpCol.ContainsKey(kvp.Key) = False Then

                'Console.WriteLine("{0} {1} ", kvp.Key, kvp.Value)
                'DebugProperties(kvp.Value)

                Dim ea As New USBWatcherEventArgs(kvp.Value("DeviceID").ToString,
                                      SafeString(kvp.Value("VolumeName")),
                                      SafeString(kvp.Value("VolumeSerialNumber")))

                RaiseEvent DeviceAdded(Me, ea)

                'rebuild baseline for next event
                pnpCol = col

            End If
        Next

    End Sub

    Private Sub ProcessRemoval(col As Dictionary(Of String,
                    Management.ManagementObject))
        For Each kvp As KeyValuePair(Of String, 
                          Management.ManagementObject) In pnpCol
            If col.ContainsKey(kvp.Key) = False Then

                'Console.WriteLine("{0} {1} ", kvp.Key, kvp.Value)
                'DebugProperties(kvp.Value)

                Dim ea As New USBWatcherEventArgs(kvp.Value("DeviceID").ToString,
                                      SafeString(kvp.Value("VolumeName")),
                                      SafeString(kvp.Value("VolumeSerialNumber")))

                RaiseEvent DeviceRemoved(Me, ea)

                'rebuild baseline for next event
                pnpCol = col

            End If
        Next

    End Sub

    ' lots of things can be NOTHING depending on the manufacturer's
    ' attention to detail.  try to avoid NRE
    Private Function SafeString(obj As Object) As String

        If obj.GetType Is GetType(String) Then
            Return CType(obj, String)
        Else
            If obj IsNot Nothing Then
                Return obj.ToString
            Else
                Return "???"
            End If
        End If

    End Function

    ' debug tool to poll a management object to get the properties and values
    Private Sub DebugProperties(mo As Management.ManagementObject)

        For Each pd As PropertyData In mo.Properties
            If pd.Value IsNot Nothing Then
                Console.WriteLine("{0} {1}", pd.Name,
                                  If(pd.Value IsNot Nothing,
                                     pd.Value.ToString,
                                     "Nothing"))
            End If

        Next
    End Sub

End Class

如何实现 USBWatcher

' local variable to catch events
Private WithEvents watcher As USBWatcher

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    watcher = New USBWatcher
    watcher.StartWatching()     ' or add to a button click
    ' I DONT have it starting automatically when you create the watcher

End Sub

Device Watcher 在不同的线程上运行，因此如果您想向控件发布通知，则必须使用委托(delegate):

Delegate Sub AddListItem(text As String)
Private myDelegate As AddListItem = New AddListItem(AddressOf AddNewListItem)

Private Sub AddNewListItem(text As String)
    myListBox.Items.Add(text)
End Sub

然后从设备添加事件，例如:

Private Sub watcher_DeviceAdded(sender As Object, 
            e As USBWatcher.USBWatcherEventArgs) Handles watcher.DeviceAdded

    Console.Beep()

    Dim msg As String = String.Format("Drive {0} ({1})   {2}", 
                                       e.DriveLetter,
                                       e.VolumeName, "Inserted")
    If myListBox.InvokeRequired Then
        myListBox.Invoke(myDelegate, New Object() {msg})
    Else
        myListBox.Items.Add(msg)
    End If

End Sub

DeviceRemoved 与消息文本中的第三个参数“Removed”不同。

USBWatcher 还有一个 StopWatching关闭观察器一段时间的方法， StartWatching启动并重新启动它。您的应用程序应该调用 StopWatching当应用程序结束时以防止 COM 错误；只需添加 watcher.StopWatching在表单关闭事件中。

这可以满足您的要求 - 在插入可移动媒体时引发事件并返回有关它们的信息 - 只是不完全符合您的要求。它使用久经考验的 WMI 而不是 Win8 方法，该方法在 MSDN 上只有稀疏的文档，并且只能在 Win8 上工作。