这将监视 USB 驱动器的到达和移除，并报告驱动器号、卷标和设备序列号。为了您的方便，它提出了 2 个事件：
Public Event DeviceAdded(sender As Object, e As USBWatcherEventArgs)
Public Event DeviceRemoved(sender As Object, e As USBWatcherEventArgs)
这只监视添加/删除的新驱动器，它不会检测诸如 CD 弹出或插入或将介质插入读卡器插槽之类的情况。
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
设备观察程序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 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中，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。
USB观察者还有一个StopWatching暂时关闭观察者的方法，以及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。
这可以满足您的需求 - 在插入可移动媒体时引发事件并返回有关它们的信息 - 只是不完全一样how你想要它。它使用久经考验的 WMI，而不是 Win8 方法，而 Win8 方法在 MSDN 上只有稀疏的文档，并且只能在 Win8 上运行。
