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检测串行端口插入/删除

serial-port wmi .net

21

Pat · 技术社区 · 15 年前

我正在连接USB到串行端口,可以随时插入或移除。我发现我可以用 WMI (特别是使用 WMI Code Creator )查询PC中的设备更改。

在下面生成的代码片段中 Win32_DeviceChangeEvent 已订阅。不过,这件事并没有透露 哪个设备 (例如USB、串行端口等)导致了该事件。有没有办法只在插入或删除串行端口时接收通知?

为了澄清,代码的要点是不检测 开/关 对于串行端口,它是为了检测新的端口已添加到计算机,或者以前的端口是 远离的 .

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

namespace WMISample
{
    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(10000);

                // Stop listening for events
                watcher.Stop();
                return;
            }
            catch(ManagementException err)
            {
                MessageBox.Show("An error occurred while trying to receive an event: " + err.Message);
            }
        }

        private void HandleEvent(object sender,
            EventArrivedEventArgs e)
        {
            Console.WriteLine("Win32_DeviceChangeEvent event occurred.");
        }

        public static void Main()
        {
            WMIReceiveEvent receiveEvent = new WMIReceiveEvent();
            return;
        }

    }
}

5 回复 | 直到 13 年前

1

21

Pat 15 年前

最后我使用了WMI和@Hans的建议来检查哪些串行端口是新的/丢失的。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Diagnostics.Contracts;
using System.IO.Ports;
using System.Management;

public static class SerialPortService
{
    private static SerialPort _serialPort;

    private static string[] _serialPorts;

    private static ManagementEventWatcher arrival;

    private static ManagementEventWatcher removal;

    static SerialPortService()
    {
        _serialPorts = GetAvailableSerialPorts();
        MonitorDeviceChanges();
    }

    /// <summary>
    /// If this method isn't called, an InvalidComObjectException will be thrown (like below):
    /// System.Runtime.InteropServices.InvalidComObjectException was unhandled
    ///Message=COM object that has been separated from its underlying RCW cannot be used.
    ///Source=mscorlib
    ///StackTrace:
    ///     at System.StubHelpers.StubHelpers.StubRegisterRCW(Object pThis, IntPtr pThread)
    ///     at System.Management.IWbemServices.CancelAsyncCall_(IWbemObjectSink pSink)
    ///     at System.Management.SinkForEventQuery.Cancel()
    ///     at System.Management.ManagementEventWatcher.Stop()
    ///     at System.Management.ManagementEventWatcher.Finalize()
    ///InnerException: 
    /// </summary>
    public static void CleanUp()
    {
        arrival.Stop();
        removal.Stop();
    }

    public static event EventHandler<PortsChangedArgs> PortsChanged;

    private static void MonitorDeviceChanges()
    {
        try
        {
            var deviceArrivalQuery = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 2");
            var deviceRemovalQuery = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 3");

            arrival = new ManagementEventWatcher(deviceArrivalQuery);
            removal = new ManagementEventWatcher(deviceRemovalQuery);

            arrival.EventArrived += (o, args) => RaisePortsChangedIfNecessary(EventType.Insertion);
            removal.EventArrived += (sender, eventArgs) => RaisePortsChangedIfNecessary(EventType.Removal);

            // Start listening for events
            arrival.Start();
            removal.Start();
        }
        catch (ManagementException err)
        {

        }
    }

    private static void RaisePortsChangedIfNecessary(EventType eventType)
    {
        lock (_serialPorts)
        {
            var availableSerialPorts = GetAvailableSerialPorts();
            if (!_serialPorts.SequenceEqual(availableSerialPorts))
            {
                _serialPorts = availableSerialPorts;
                PortsChanged.Raise(null, new PortsChangedArgs(eventType, _serialPorts));
            }
        }
    }

    public static string[] GetAvailableSerialPorts()
    {
        return SerialPort.GetPortNames();
    }
}

public enum EventType
{
    Insertion,
    Removal,
}

public class PortsChangedArgs : EventArgs
{
    private readonly EventType _eventType;

    private readonly string[] _serialPorts;

    public PortsChangedArgs(EventType eventType, string[] serialPorts)
    {
        _eventType = eventType;
        _serialPorts = serialPorts;
    }

    public string[] SerialPorts
    {
        get
        {
            return _serialPorts;
        }
    }

    public EventType EventType
    {
        get
        {
            return _eventType;
        }
    }
}

这个 MonitorDeviceChanges 方法实际上可以看到所有设备更改(如设备管理器),但检查串行端口只允许在这些更改发生时引发事件。

要使用代码,只需订阅 PortsChanged 事件,例如。 SerialPortService.PortsChanged += (sender1, changedArgs) => DoSomethingSerial(changedArgs.SerialPorts);

哦,还有 .Raise 方法只是我在某个地方学到的一种扩展方法:

/// <summary>
/// Tell subscribers, if any, that this event has been raised.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="handler">The generic event handler</param>
/// <param name="sender">this or null, usually</param>
/// <param name="args">Whatever you want sent</param>
public static void Raise<T>(this EventHandler<T> handler, object sender, T args) where T : EventArgs
{
    // Copy to temp var to be thread-safe (taken from C# 3.0 Cookbook - don't know if it's true)
    EventHandler<T> copy = handler;
    if (copy != null)
    {
        copy(sender, args);
    }
}

2

Journeyman 11 年前

注:我试着把这篇文章作为对@Pat答案的评论,但没有足够的声誉来做这件事。

根据@2pietjuh2的注释,RaisePortsChangedIfNecessary()可以更改为以下内容:

private static void RaisePortsChangedIfNecessary(EventType eventType)
{
    lock (_serialPorts)
    {
        var availableSerialPorts = GetAvailableSerialPorts();
        if (eventType == EventType.Insertion)
        {
            var added = availableSerialPorts.Except(_serialPorts).ToArray();
            _serialPorts = availableSerialPorts;
            PortsChanged.Raise(null, new PortsChangedArgs(eventType, added));
        }
        else if (eventType == EventType.Removal)
        {
            var removed = _serialPorts.Except(availableSerialPorts).ToArray();
            _serialPorts = availableSerialPorts;
            PortsChanged.Raise(null, new PortsChangedArgs(eventType, removed));
        }
    }
}

然后引发的事件包括插入/删除的串行端口,而不是插入/删除后可用的串行端口列表。

3

2

Wolf 10 年前

不。去看看SerialPort.GetPortNames()发生了什么。倾听 WM_DEVICECHANGE 窗口中的消息可以提供更好的信息。

4

1

Tergiver 15 年前

这是一个精简版的 DeviceChangeEvents 通知类我写了一段时间以前,虽然我从来没有完全完成它。我把所有的东西都去掉了,除了移植的事件,因为它完全不同。

using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;

public sealed class PortArrivalEventArgs : EventArgs
{
    public string Name { get; private set; }
    public PortArrivalEventArgs(string name) { Name = name; }
}

public static class DeviceChangeEvents
{
    #region Events

    #region PortArrived
    private static object PortArrivedEvent = new Object();
    public static event EventHandler<PortArrivalEventArgs> PortArrived
    {
        add { AddEvent(PortArrivedEvent, value); }
        remove { RemoveEvent(PortArrivedEvent, value); }
    }
    private static void FirePortArrived(IntPtr lParam)
    {
        EventHandler<PortArrivalEventArgs> handler
            = (EventHandler<PortArrivalEventArgs>)events[PortArrivedEvent];
        if (handler != null)
        {
            string portName = Marshal.PtrToStringAuto((IntPtr)((long)lParam + 12));
            handler(null, new PortArrivalEventArgs(portName));
        }
    }
    #endregion

    #endregion

    #region Internal

    private static EventHandlerList events = new EventHandlerList();
    private static MessageWindow messageWindow = null;

    private static void AddEvent(object key, Delegate value)
    {
        events.AddHandler(key, value);
        if (messageWindow == null)
            messageWindow = new MessageWindow();
    }

    private static void RemoveEvent(object key, Delegate value)
    {
        events.RemoveHandler(key, value);

        // In the more complete version of DeviceChangedEvents, System.ComponentModel.EventHandlerList
        //  is replaced by an identical event storage object which exposes a count of the number of
        //  handlers installed. It also removes empty handler stubs. Both of these are required
        //  to safely destroy the message window when the last handler is removed.

        //if (messageWindow != null && events.Count == 0)
        //    messageWindow.DestroyHandle();
    }

    #endregion

    private sealed class MessageWindow : NativeWindow
    {
        public MessageWindow()
        {
            CreateParams cp = new CreateParams();
            cp.Caption = GetType().FullName;
            // NOTE that you cannot use a "message window" for this broadcast message
            //if (Environment.OSVersion.Platform == PlatformID.Win32NT)
            //  cp.Parent = (IntPtr)(-3); // HWND_MESSAGE
            //Debug.WriteLine("Creating MessageWindow " + cp.Caption);
            CreateHandle(cp);
        }

        const int WM_DESTROY = 0x02;
        const int WM_DEVICECHANGE = 0x219;

        enum DBT
        {
            DEVICEARRIVAL = 0x8000,
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == WM_DESTROY)
            {
                messageWindow = null;
            }
            else if (m.Msg == WM_DEVICECHANGE)
            {
                DBT changeType = (DBT)m.WParam;
                int deviceType = m.LParam == IntPtr.Zero ? 0 : Marshal.ReadInt32(m.LParam, 4);

                Debug.WriteLine(String.Format("WM_DEVICECHANGE changeType = {0}, deviceType = {1}", changeType, deviceType));

                switch (changeType)
                {
                    case DBT.DEVICEARRIVAL:
                        switch (deviceType)
                        {
                            case 3: // DBT_DEVTYP_PORT
                                FirePortArrived(m.LParam);
                                break;
                        }
                        break;
                }
            }

            base.WndProc(ref m);
        }
    }
}

5

0

alyeomans 12 年前

您的设备更改事件可以与WMI-PNP实体一起使用。下面将返回设备详细信息-在下面的代码中显示设备名称。

Dim moReturn As Management.ManagementObjectCollection
Dim moSearch As Management.ManagementObjectSearcher
Dim mo As Management.ManagementObject
moSearch = New Management.ManagementObjectSearcher("Select * from Win32_PnPEntity")
moReturn = moSearch.Get

For Each mo In moReturn
If CStr(mo.Properties.Item("Name").Value).Contains("Prolific") Then
    returns something like: "Prolific USB-to-Serial Comm Port (COM17)"
    txtStatus.Text &= CStr(mo.Properties.Item("Name").Value) & vbCrLf
End If
Next

另请参阅访问可用于筛选或监视更改的其他PNP属性的代码:

On Error Resume Next
strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
Set colItems = objWMIService.ExecQuery("Select * from Win32_PnPEntity",,48)
For Each objItem in colItems
    "Availability: " & objItem.Availability
    "Caption: " & objItem.Caption
    "ClassGuid: " & objItem.ClassGuid
    "ConfigManagerErrorCode: " & objItem.ConfigManagerErrorCode
    "ConfigManagerUserConfig: " & objItem.ConfigManagerUserConfig
    "CreationClassName: " & objItem.CreationClassName
    "Description: " & objItem.Description
    "DeviceID: " & objItem.DeviceID
    "ErrorCleared: " & objItem.ErrorCleared
    "ErrorDescription: " & objItem.ErrorDescription
    "InstallDate: " & objItem.InstallDate
    "LastErrorCode: " & objItem.LastErrorCode
    "Manufacturer: " & objItem.Manufacturer
    "Name: " & objItem.Name
    "PNPDeviceID: " & objItem.PNPDeviceID
    "PowerManagementCapabilities: " & objItem.PowerManagementCapabilities
    "PowerManagementSupported: " & objItem.PowerManagementSupported
    "Service: " & objItem.Service
    "Status: " & objItem.Status
    "StatusInfo: " & objItem.StatusInfo
    "SystemCreationClassName: " & objItem.SystemCreationClassName
    "SystemName: " & objItem.SystemName
Next