Delphi - 你不知道的函数

技术交流,DH讲解.

在Sysutils.pas有几个函数,以前我也没有看见过,今天看源码的时候无意间发现了.

function GDAL: LongWord;
type
  TDVCLAL = array[0..3] of LongWord;
  PDVCLAL = ^TDVCLAL;
var
  P: Pointer;
  A1, A2: LongWord;
  PAL1s, PAL2s: PDVCLAL;
  ALOK: Boolean;
begin
  P := ALR;//从资源文件获得
  if P <> nil then
  begin
    A1 := AL1(P^);
    A2 := AL2(P^);
    Result := A1;
    PAL1s := @AL1s;
    PAL2s := @AL2s;
    ALOK := ((A1 = PAL1s[0]) and (A2 = PAL2s[0])) or
            ((A1 = PAL1s[1]) and (A2 = PAL2s[1])) or
            ((A1 = PAL1s[2]) and (A2 = PAL2s[2]));
    FreeResource(Integer(P));
    if not ALOK then ALV;//抛出异常,说Application is not licensed to use this feature
  end
  else Result := AL1s[3];
end;

这个函数全称Get Delphi Access Licences,这个函数去读取资源里面的访问许可,如果不合法就抛出异常,如果合法就返回解密后的AL1。里面用到的两个函数:

const
  AL1s: array[0..3] of LongWord = ($FFFFFFF0, $FFFFEBF0, 0, $FFFFFFFF);
  AL2s: array[0..3] of LongWord = ($42C3ECEF, $20F7AEB6, $D1C2F74E, $3F6574DE);

procedure ALV;
begin
  raise Exception.CreateRes(@SNL);
end;

function ALR: Pointer;
var
  LibModule: PLibModule;
begin
  if MainInstance <> 0 then
    Result := Pointer(LoadResource(MainInstance, FindResource(MainInstance, 'DVCLAL',
      RT_RCDATA)))
  else
  begin
    Result := nil;
    LibModule := LibModuleList;//这里是一个链表,其实想学习链表的朋友可以来看看
    while LibModule <> nil do//遍历链表
    begin
      with LibModule^ do
      begin
        Result := Pointer(LoadResource(Instance, FindResource(Instance, 'DVCLAL',
          RT_RCDATA)));
        if Result <> nil then Break;
      end;
      LibModule := LibModule.Next;
    end;
  end;
end;

紧接着下面有个函数用到GDAL了,也就是GDAL没有直接被用到:

procedure RCS;
var
  P: Pointer;
  ALOK: Boolean;
begin
  P := ALR;
  if P <> nil then
  begin
    ALOK := (AL1(P^) = AL1s[2]) and (AL2(P^) = AL2s[2]);
    FreeResource(Integer(P));
  end
  else
    ALOK := False;
  if not ALOK then
    ALV;
end;

procedure RPR;
var
  AL: LongWord;
begin
  AL := GDAL;
  if (AL <> AL1s[1]) and (AL <> AL1s[2]) then
    ALV;
end;

函数RCS:检查是否有合法的Delphi Client Server许可,不合法就异常.
函数RPR:检查是否有合法的Delphi Pro 许可,不合法就异常.

从上面看,这两个函数我们平时基本用不着了,也是,这两个函数在自带的VCL里面有.有兴趣的朋友可以自己看一下.

OK