问题
I'm a WinForms developer and I already knew how to monitor the USB's that connects or disconnects using WMI, but time ago I'd discovered the DeviceWatcher class for Modern Windows Apps, that Class has interested at first time 'cause seems like a very improved and efficient alternative to replace all those 'old' WMI codes that explains how to monitor drives over Internet, but until yesterday (thanks to this post) I haven't idea about how to use the DeviceWatcher in a WinForms project, but now I'm using the DeviceWatcher in a WinForms project.
The problem is that maybe I'm wrong but I think that this is not really what I expected, just I can't find any kind of documentation about the DeviceWatcher (only the MSDN example above) and I can't find the way to retrieve the necessary information to monitor the drive events, I've tried to handle all the events of the DeviceWatcher to print out in the Debug console all the data contained in the arguments with the hope to find something that could help me ...but not, I'm very stuck with the usage of the DeviceWatcher Class and I can't imagine how to procceed.
When I connect or disconnect an USB I just see two things, the Hardware ID and the 'InterfaceEnabled' property (that I don't know if that determines the Device Availability), nothing interesting more.
What I have accomplished:
· Retrieve the Hardware Device ID's.
What I would like to accomplish:
· Retrieve the Device type (to difference between USB and other kind of devices) when the device is connected, disconnecting, and disconnected.
· Retrieve the Device Availability (I mean whether the device is accessible to read/write data on it) when the device is connected, disconnecting, and disconnected.
· Retrieve the Device Letter when the device is connected, disconnecting, and disconnected.
· Retrieve the Device Label-Description when the device is connected, disconnecting, and disconnected.
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
回答1:
This will watch for the Arrival and Removal of USB drives, and report the DriveLetter, Volume Label and device serial number. It raises 2 Events for your convenience:
Public Event DeviceAdded(sender As Object, e As USBWatcherEventArgs)
Public Event DeviceRemoved(sender As Object, e As USBWatcherEventArgs)
This only watches for a new drive added/removed, it will not detect things like a CD being ejected or inserted, or inserting media into a card reader slot.
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
How to Implement 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
The Device Watcher runs on a different thread so if you want to post a notice to a control, you will have to use a 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
Then from the Device Added event, for example:
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 would be the same except "Removed" as the third param in the message text.
USBWatcher also has a StopWatching method to turn off the watcher for a time, and StartWatching to start and restart it. Your app should call StopWatching when the app ends to prevent COM errors; just add watcher.StopWatching in the form close event.
This does what you want - raise events when removable media is inserted and return the information about them - just not exactly how you wanted it. It uses tried and tested WMI rather than the Win8 method, which is as yet has only sparse documention on MSDN and would only work on Win8.
回答2:
you can use WMI to detect, if pen drive is inserted. You have to add reference to the System.Management dll of dotnet framework.
you can get Devide Details as :
Public Function SerialNO(ByVal DriveNameWithColon As String) As String
Dim disk As ManagementObject = New ManagementObject("win32_logicaldisk.deviceid='" + DriveNameWithColon + "'")
disk.Get()
Return disk("VolumeSerialNumber").ToString()
End Function
回答3:
You can get PnPObject from the interface ID which will give you more device specific information.
public static IAsyncOperation<PnpObject> CreateFromIdAsync(
PnpObjectType type,
string id,
IEnumerable<string> requestedProperties
)
seems pretty interesting fellah. You have few different options to specfy for PnpObjectType,
DeviceInterface | deviceInterface - The PnpObject represents a device interface.
DeviceContainer | deviceContainer - The PnpObject represents a device container.
Device | device -The PnpObject represents a device.
DeviceInterfaceClass | deviceInterfaceClass - The PnpObject represents a device interface class.
The id actually is interface id, which you already received.
Also note that you have list of properties you can ask for(requstedProperties argument): http://msdn.microsoft.com/en-us/library/hh464997.aspx#ListOfCanonicalProperties.
It's true that there's not too much for you, but don't be scared. There's a lot more of them: http://msdn.microsoft.com/en-us/library/ff553416.aspx
If you check devpkey.h, you can find interesting properties, such as:
- DEVPKEY_Device_DevType
- DEVPKEY_Storage_Removable_Media
- DEVPKEY_Storage_Portable -
Some of the things are device specfc, some of not. You can get even more properties through devmgmt.msc(Details->Property). There's also bunch of stuff in the registry. The Unified device property model discusses this: http://msdn.microsoft.com/en-us/library/ff553515(v=vs.85).aspx
PnP api has following methods:
Await DeviceInformation.FindAllAsync()
Await Pnp.PnpObject.FindAllAsync(Pnp.PnpObjectType.DeviceContainer, ...)
Await Pnp.PnpObject.FindAllAsync(Pnp.PnpObjectType.Device, ...)
Await Pnp.PnpObject.FindAllAsync(Pnp.PnpObjectType.DeviceInterface, ...)
Await Pnp.PnpObject.FindAllAsync(Pnp.PnpObjectType.DeviceInterfaceClass, ...)
Await Pnp.PnpObject.CreateFromIdAsync(..., id, ...)
You can read this article: http://www.codeproject.com/Articles/458550/Device-enumeration-in-Windows
It has everything, source code, keys, and shows how to dump all the properties from devices into file. This way you can see what properties your USB stick has.
来源：https://stackoverflow.com/questions/24944865/monitor-usb-drives-and-retrieve-device-info-using-a-devicewatcher