using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;using System.Runtime.InteropServices;namespace WindowsApplication16{ public partial class Form1 : Form {  public Form1()  {   InitializeComponent();  }  [StructLayout(LayoutKind.Sequential)]  public struct DEV_BROADCAST_VOLUME  {   public int dbcv_size;   public int dbcv_devicetype;   public int dbcv_reserved;   public int dbcv_unitmask;  }  protected override void WndProc(ref Message m)  {   // 發生設備變動   const int WM_DEVICECHANGE = 0x0219;   // 系統檢測到一個新設備   const int DBT_DEVICEARRIVAL = 0x8000;   // 系統完成移除一個設備   const int DBT_DEVICEREMOVECOMPLETE = 0x8001;   // 邏輯卷標   const int DBT_DEVTYP_VOLUME = 0x00000002;   switch (m.Msg)   {    case WM_DEVICECHANGE:     switch (m.WParam.ToInt32())     {      case DBT_DEVICEARRIVAL:       int devType = Marshal.ReadInt32(m.LParam, 4);       if (devType == DBT_DEVTYP_VOLUME)       {        DEV_BROADCAST_VOLUME vol;        vol = (DEV_BROADCAST_VOLUME)Marshal.PtrToStructure(         m.LParam, typeof(DEV_BROADCAST_VOLUME));        MessageBox.Show(vol.dbcv_unitmask.ToString("x"));       }       break;      case DBT_DEVICEREMOVECOMPLETE:       MessageBox.Show("Removal");       break;     }     break;   }   base.WndProc(ref m);  } }}