共享内存问题,请高手出招啊..............

Question

  fMapHandle := OpenFileMapping(FILE_MAP_ALL_ACCESS, BOOL(True), PChar('search_his'));
  fWasAlreadyOpen := (fMapHandle <> 0);
  if not fWasAlreadyOpen then
     fMapHandle := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, 8196,'search_his');     
  if   fMapHandle   =   0   then
     raise Exception.Create( 'CreateFileMapping  failed with error code '+IntToStr(GetLastError)); 上面已经创建了内存块,问题是我写不进去,而且写进去的是 Unicode 码
   转码部分已经做啦,用 CopyMemory API写时出错,请高手给个CopyMemory使用例子,谢谢CopyMemory(Destination: Pointer; Source: Pointer; Length: DWORD);   

Answer 1

 PShareMem = ^TShareMem;
  TShareMem = record
    Data: array[0..255] of char;
  end;procedure TForm1.Button1Click(Sender: TObject);
var
  str: pchar;
begin
  str := pchar('共享内存');
  CopyMemory(@(pShare^.data), Str, Length(str));
end;

Answer 2

CreateFileMapping/OpenFileMapping之后还需要执行MapViewOfFile将镜像关联到内存才能操作

Answer 3

type
  PShareMem = ^TShareMem;
  TShareMem = record
    Data: array[0..255] of char;
  end;
var
  PShare: PShareMem;
  HMapping: THandle;
procedure OpenMap;
begin
   {创建一个文件映射内核对象}
  HMapping := CreateFileMapping($FFFFFFFF,nil,PAGE_READWRITE,0,SizeOf(TShareMem),            pchar('Map Name'));
  if (hMapping = 0) then
  begin
    Application.Terminate;
    exit;
  end;
   {将文件数据映射到进程的地址空间}
  PShare := PShareMem(MapViewOfFile(HMapping, FILE_MAP_ALL_ACCESS, 0, 0, 0));
  if PShare = nil then
  begin
    CloseHandle(HMapping);
    Application.Terminate;
    exit;
  end;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
  str: pchar;
begin
  str := pchar('共享内存');
  CopyMemory(@(pShare^.data), Str, Length(str));
end;

Answer 4

Type
  TData = record
    Str: array[0..255] of Char;
  end;
procedure CreateShareFile;
begin
  FHandle := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, SizeOf(TData), 'MapMEM');
  if FHandle <> 0 then
  begin
    FDLLData := MapViewOfFile(FHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
    if FDLLData <> nil then StrLCopy(FDllData.Str, PChar(ExtractFilePath(Paramstr(0))), 255);
  end;
end;
调用:
function GetStr: string;
var
  FHandle: LongWORD;
  DLLData: PData;
  _Str: string;
begin
  FHandle := OpenFileMapping(PAGE_READWRITE, False, 'MapMEM');
  if FHandle <> 0 then
  try
    DLLData := MapViewOfFile(FHandle, FILE_MAP_READ, 0, 0, 0);
    if DLlData <> nil then
    try
      Result := DllData.Str;
    finally
      UnmapViewOfFile(DLLData);
    end;
  finally
    CloseHandle(FHandle);
  end;
end;