C#如何打开关闭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 );