Windows API监控：实时检测USB串口插入与拔除

#region 监听串口插入 拔出

        public const Int32 WM_DEVICE_CHANGE = 0x219;
        public const Int32 DBT_DEVICEARRIVAL = 0x8000;
        public const Int32 DBT_DEVICE_REMOVE_COMPLETE = 0x8004;
        public const Int32 DBT_DEVTYP_PORT = 0x00000003;

        [StructLayout(LayoutKind.Sequential)]
        public struct DEV_BROADCAST_HDR
        {
            public UInt32 dbch_size;
            public UInt32 dbch_devicetype;
            public UInt32 dbch_reserved;
        }

        [StructLayout(LayoutKind.Sequential)]
        protected struct DEV_BROADCAST_PORT_Fixed
        {
            public UInt32 dbcp_size;
            public UInt32 dbcp_devicetype;
            public UInt32 dbcp_reserved;
        }
        protected override void WndProc(ref Message m)
        {
            if (m.Msg == WM_DEVICE_CHANGE)
            {
                switch (m.WParam.ToInt32())
                {
                    case DBT_DEVICEARRIVAL: //串口插入
                        DEV_BROADCAST_HDR dbhdr = (DEV_BROADCAST_HDR)Marshal.PtrToStructure(m.LParam, typeof(DEV_BROADCAST_HDR));