excel在delphi操作时什么时候释放资源？

Question

button的click事件：
{   Opendialog1.InitialDir := ExtractFileDir(paramstr(0));
   opendialog1.Execute;
   try
      excelapplication1.Connect;//
   except
      MessageDlg('Excel may not be installed',mtError,[mbOk],0);
      abort;
   end;
   excelapplication1.Visible[0] := true;
   excelapplication1.Caption := 'Excel Application';
   Try
      excelapplication1.Workbooks.Open(opendialog1.FileName,
  null,null,null,null,null,null,null,null,null,null,null,null,0);
   except
      begin
        excelapplication1.Disconnect;
        excelapplication1.Quit;
        showmessage('选择Excel错误');
        exit;
      end;
   end;   excelworkbook1.ConnectTo(excelapplication1.Workbooks[1]);
   excelworksheet1.ConnectTo(excelworkbook1.Worksheets[1] as _worksheet);
   
   //添入数据信息
   excelworksheet1.Cells.Item[6,2]:='data';
    excelapplication1.Disconnect;
}如果在这里写入excelapplication1.quit/则执行时excel直接退出。
如果什么都不写，则excel资源没有释放掉，程序报错/不知道有碰到类似问题的朋友吗？
在什么地方释放资源合适呢？或者写在什么位置？谢谢各位！！

Answer 1

button的click事件：
{   Opendialog1.InitialDir := ExtractFileDir(paramstr(0));
   opendialog1.Execute;
   try
      excelapplication1.Connect;//
   except
      MessageDlg('Excel may not be installed',mtError,[mbOk],0);
      abort;
   end;
   excelapplication1.Visible[0] := true;
   excelapplication1.Caption := 'Excel Application';
   Try
      excelapplication1.Workbooks.Open(opendialog1.FileName,
  null,null,null,null,null,null,null,null,null,null,null,null,0);
   except
      begin
        excelapplication1.Disconnect;
        excelapplication1.Quit；//YES
        showmessage('选择Excel错误');
        exit;
      end;
   end;   excelworkbook1.ConnectTo(excelapplication1.Workbooks[1]);
   excelworksheet1.ConnectTo(excelworkbook1.Worksheets[1] as _worksheet);
   
   //添入数据信息
   excelworksheet1.Cells.Item[6,2]:='data';
    excelapplication1.Disconnect;
   //this place write it 
}

Answer 2

button的click事件：
{   Opendialog1.InitialDir := ExtractFileDir(paramstr(0));
   opendialog1.Execute;
   try
      excelapplication1.Connect;//
   except
      MessageDlg('Excel may not be installed',mtError,[mbOk],0);
      abort;
   end;
   excelapplication1.Visible[0] := true;
   excelapplication1.Caption := 'Excel Application';
   Try
      excelapplication1.Workbooks.Open(opendialog1.FileName,
  null,null,null,null,null,null,null,null,null,null,null,null,0);
   except
      begin
        excelapplication1.Disconnect;
        excelapplication1.Quit；//YES
        showmessage('选择Excel错误');
        exit;
      end;
   end;   excelworkbook1.ConnectTo(excelapplication1.Workbooks[1]);
   excelworksheet1.ConnectTo(excelworkbook1.Worksheets[1] as _worksheet);
   
   //添入数据信息
   excelworksheet1.Cells.Item[6,2]:='data';
    excelapplication1.Disconnect;
   //this place write it 
}

Answer 3

如果在excelapplication1.disconnect后边直接写excelapplication1.quit;
则excel直接退出啊。不能对excel进行操作了。

Answer 4

我都是用OLE去创建EXCEL的各种对象的

Answer 5

excelapplication1 := Unassigned;
VarClear(excelapplication1);

Answer 6

我是这样解决的！定义一个Boolean，然后判断是否打开过Excel!是则在推出时：quit;