C#获取硬盘序列号

using System;
using System.Runtime.InteropServices;

namespace ArLi.CommonPrj {

 #region how use this?
 /*
  string sVol = getvol.GetVolOf("C");
 */
 #endregion

 public class getvol{

  [DllImport("kernel32.dll")]
  private static extern int GetVolumeInformation(
   string  lpRootPathName,
   string  lpVolumeNameBuffer,
   int  nVolumeNameSize,
   ref int  lpVolumeSerialNumber,
   int  lpMaximumComponentLength,
   int  lpFileSystemFlags,
   string  lpFileSystemNameBuffer,
   int  nFileSystemNameSize
   );

  public static string GetVolOf(string drvID){
   const int MAX_FILENAME_LEN = 256;
   int retVal = 0;
   int a =0;
   int b =0;
   string str1 = null;
   string str2 = null;

   int i = GetVolumeInformation(
    drvID + @":/",
    str1,
    MAX_FILENAME_LEN,
    ref retVal,
    a,
    b,
    str2,
    MAX_FILENAME_LEN
    );

   return retVal.ToString("x");
  }
 }
}