比较两个文件是否相同（比较两个流是否相等）

Posted 2022-08-11 YanJinrong

function CompareStream(// 比较两个流是否相等
  mStream1, mStream2: TStream // 两个流
): Boolean;// 返回两个流是否相等
var
  vBuffer1, vBuffer2: array[0..$1000-1] of Char;
  vLength1, vLength2: Integer;
begin
  Result := mStream1 = mStream2;
  if Result then Exit;
  if not Assigned(mStream1) or not Assigned(mStream2) then Exit;// 其中一个为空
  while True do
  begin
    vLength1 := mStream1.Read(vBuffer1, SizeOf(vBuffer1));
    vLength2 := mStream2.Read(vBuffer2, SizeOf(vBuffer2));
    if vLength1 <> vLength2 then Exit;
    if vLength1 =0 then Break;
    if not CompareMem(@vBuffer1[0],@vBuffer2[0], vLength1) then Exit;
  end;
  Result := True;
end; CompareStream 
 
function CompareFile(// 比较两个文件是否相等
  mFileName1, mFileName2: string // 两个文件
): Boolean;// 返回两个文件是否相等
var
  vFileHandle1, vFileHandle2: THandle;
  vFileStream1, vFileStream2: TFileStream;
 
  vShortPath1, vShortPath2: array[0..MAX_PATH] of Char;
begin
  Result := False;
  if not FileExists(mFileName1) or not FileExists(mFileName2) then Exit;// 其中一个文件不存在
  GetShortPathName(PChar(mFileName1), vShortPath1, SizeOf(vShortPath1));
  GetShortPathName(PChar(mFileName2), vShortPath2, SizeOf(vShortPath2));
  Result := SameText(vShortPath1, vShortPath2);// 两个文件名是否相同
  if Result then Exit;
  vFileHandle1 := _lopen(PChar(mFileName1), OF_READ or OF_SHARE_DENY_NONE);
  vFileHandle2 := _lopen(PChar(mFileName2), OF_READ or OF_SHARE_DENY_NONE);
  Result :=(Integer(vFileHandle1)>0) and (Integer(vFileHandle2)>0);// 文件是否可以访问
  if not Result then
  begin
    _lclose(vFileHandle1);
    _lclose(vFileHandle2);
    Exit;
  end;
  Result := GetFileSize(vFileHandle1, nil)= GetFileSize(vFileHandle2, nil);// 文件大小是否一致
  if not Result then
  begin
    _lclose(vFileHandle1);
    _lclose(vFileHandle2);
    Exit;
  end;
  vFileStream1 := TFileStream.Create(vFileHandle1);
  vFileStream2 := TFileStream.Create(vFileHandle2);
  try
    Result := CompareStream(vFileStream1, vFileStream2);// 比较两个文件内容是否相同
  finally
    vFileStream1.Free;
    vFileStream2.Free;
  end;
end; CompareFile 
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  Caption := BoolToStr(
    CompareFile('c:/temp/temp1.txt','c:/temp/temp2.txt'), True);
end;