判斷檔案是否被鎖住

function IsFileInUse(FileName: TFileName): Boolean; 
var 
    HFileRes: HFILE; 
begin 
    Result := False; 
    if not FileExists(FileName) then Exit; 
    HFileRes := CreateFile(PChar(FileName), 
        GENERIC_READ or GENERIC_WRITE, 
        0, 
        nil, 
        OPEN_EXISTING, 
        FILE_ATTRIBUTE_NORMAL, 
        0); 
    Result := (HFileRes = INVALID_HANDLE_VALUE); 
    if not Result then 
        CloseHandle(HFileRes); 
end;