多个光驱，如何控制其中一个的关或开。(100分)

我已经可以开了，但无法关闭。请大家看一下，我把开的代码拿出来。如下：<br>function EjectCD(Drive : char) : bool;<br>var<br>&nbsp; mp : TMediaPlayer;<br>begin<br>&nbsp; result := false;<br>&nbsp; Application.ProcessMessages;<br>&nbsp; //if not IsDriveCD(Drive) then exit;<br>&nbsp; mp := TMediaPlayer.Create(nil);<br>&nbsp; mp.Visible := false;<br>&nbsp; mp.Parent := Application.MainForm;<br>&nbsp; mp.Shareable := true;<br>&nbsp; mp.DeviceType := dtCDAudio;<br>&nbsp; mp.FileName := Drive + ':';<br>&nbsp; mp.Open;<br>&nbsp; Application.ProcessMessages;<br>&nbsp; mp.Eject;<br>&nbsp; Application.ProcessMessages;<br>&nbsp; mp.Close;<br>&nbsp; Application.ProcessMessages;<br>&nbsp; mp.free;<br>&nbsp; result := true;<br>end;<br>注意：use &nbsp;mplayer

单个的可以使用mciSendString控制开关。<br>多个的据说就得用mciSendCommand了。但是我没有实验过。

参考下面的代码把, <br>procedure TForm1.Button2Click(Sender: TObject);<br>begin<br>with MediaPlayer1 do<br>if (MediaPlayer1.Mode = mpOpen) then<br>&nbsp; &nbsp;mciSendCommand(MediaPlayer1.DeviceID, MCI_SET, MCI_SET_DOOR_CLOSED, 0)<br>else<br>&nbsp; &nbsp;mciSendCommand(MediaPlayer1.DeviceID, MCI_SET, MCI_SET_DOOR_OPEN, 0);<br>end;<br><br>-------------- <br>　<br>　void CDEject() <br>　　{ <br>　　MCI_SET_PARMS mciset; <br>　　mciSendCommand( wDevID, MCI_SET, <br>　　MCI_SET_DOOR_OPEN | MCI_SET_OFF, <br>　　( DWORD )( LPSTR ) &amp;mciset ); <br>　　} <br>　　 <br>　　void CDBack() <br>　　{ <br>　　MCI_SET_PARMS mciset; <br>　　mciSendCommand( wDevID, MCI_SET, <br>　　MCI_SET_DOOR_CLOSED | MCI_SET_ON, <br>　　( DWORD )( LPSTR ) &amp;mciset ); <br>　　} <br>　　上面两个函数可以实现光驱托盘的弹出和收回。但是在使用这 两个函数之前，必须得到CD-ROM的设备ID号，这可以通过下面函数 来实现： <br>　　void GetAudioCDDevID() <br>　　{ <br>　　MCI_OPEN_PARMS mciOpenParms; <br>　　mciOpenParms.lpstrDeviceType = "cdaudio"; <br>　　if( mciSendCommand( 0, MCI_OPEN, MCI_OPEN_TYPE, <br>　　( DWORD )( LPVOID ) &amp;mciOpenParms ) ) { <br>　　wDevID = 0; <br>　　return; <br>　　} <br>　　wDevID = mciOpenParms.wDeviceID; <br>　　} <br>　　这里，wDevID是CD-ROM的设备ID。在上面的例子里面它应该是 一个全局变量。需要注意的是，在程序运行结束的时候需要关闭该 设备以便其他程序能够接管它，具体实现是： <br>　　BOOL CloseCDDevice() <br>　　{ <br>　　DWORD dwRes; <br>　　dwRes = mciSendCommand( wDevID, MCI_CLOSE, 0, 0 ); <br>　　return ( !( ( BOOL ) dwRes) ); <br>　　} <br>　　在具体实现的时候，一般按照： <br>　　GetAudioCDDevID(); <br>　　CDEject(); // 或者CDBack(); <br>　　CloseCDDevice(); <br>　　的顺序来调用。 <br><br><br>　　《电子与电脑》99年1期

uses mmSystem;<br>procedure CDRomOpen(bOpenDrive:boolean; cDrive:char); &nbsp;//uses mmSystem<br>var open:MCI_OPEN_PARMS;<br>&nbsp; &nbsp; status:MCI_STATUS_PARMS;<br>&nbsp; &nbsp; flags:dword;<br>&nbsp; &nbsp; szDriveName:array[0..3]of char;<br>begin<br>&nbsp; &nbsp; strcopy(szDriveName,'?:');<br>&nbsp; &nbsp; ZeroMemory(@open,sizeof(MCI_OPEN_PARMS));<br>&nbsp; &nbsp; open.lpstrDeviceType:=LPCSTR(MCI_DEVTYPE_CD_AUDIO);<br>&nbsp; &nbsp; szDriveName[0]:=cDrive;<br>&nbsp; &nbsp; open.lpstrElementName:=szDriveName;<br>&nbsp; &nbsp; flags:=MCI_OPEN_TYPE or MCI_OPEN_TYPE_ID or MCI_OPEN_ELEMENT or MCI_OPEN_SHAREABLE;<br>&nbsp; &nbsp; if mciSendCommand(0,MCI_OPEN,flags,LongWord(@open))=0 then<br>&nbsp; &nbsp; &nbsp; begin<br>&nbsp; &nbsp; &nbsp; &nbsp; status.dwItem:=MCI_STATUS_READY;<br>&nbsp; &nbsp; &nbsp; &nbsp; if (bOpenDrive) then <br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mciSendCommand(open.wDeviceID,MCI_SET,MCI_SET_DOOR_OPEN,0)<br>&nbsp; &nbsp; &nbsp; &nbsp; else <br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mciSendCommand(open.wDeviceID,MCI_SET,MCI_SET_DOOR_CLOSED,0);<br>&nbsp; &nbsp; &nbsp; &nbsp; mciSendCommand(open.wDeviceID,MCI_CLOSE,MCI_WAIT,0);<br>&nbsp; &nbsp; &nbsp; end;<br>end;<br>procedure TForm1.BitBtn1Click(Sender: TObject);<br>begin<br>&nbsp; CDRomOpen(true,'I'); &nbsp;// open cd<br>end;<br><br>procedure TForm1.BitBtn2Click(Sender: TObject);<br>begin<br>&nbsp; CDRomOpen(false,'I'); // &nbsp;Close cd<br>end;

nzfsoft的经试验，确定可行。其它人的没成功。

多人接受答案了。