C# 打开关闭CDROM

using System;
using System.Text;
using System.Runtime.InteropServices;

class CloseCD
{
[DllImport("winmm.dll",EntryPoint="mciSendStringA",CharSet=CharSet.Ansi )]
 protected static extern int mciSendString( string lpstrCommand, StringBuilder lpstrReturnString, int uReturnLength, IntPtr hwndCallback );
  public static void Main()
  {
    int ret = mciSendString( "set cdaudio door open", null, 0, IntPtr.Zero );
    Console.ReadLine();
    ret = mciSendString( "set cdaudio door closed", null, 0, IntPtr.Zero );
  }
}