EXE与DLL共享文件

[JB7]

我想在EXE中创建一个合局的clientdataset对象，想在DLL中也能访问这个变量，该如何操作，效果最高，
另外有个问题，要防止多个DLL同时操作这个对象导致异常现象。

[yuqianyi1974]

内存影像文件

[yuqianyi1974]

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

const
  WM_DATA = WM_USER + 1024;
type
  PShareMem = ^TShareMem;
  TShareMem = record
    Data: array[0..255] of char;
  end;
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }

  end;

var
  Form1: TForm1;
  PShare: PShareMem;
implementation

{$R *.DFM}
var
  HMapping: THandle;
  HMapMutex: THandle;
const
  MAPFILESIZE = 1000;
  REQUEST_TIMEOUT = 1000;

procedure OpenMap;
begin
   {创建一个文件映射内核对象}
  HMapping := CreateFileMapping(
    $FFFFFFFF,
    nil,
    PAGE_READWRITE,
    0,
    SizeOf(TShareMem),
                 {这个文件映射对象的名字用于与其他进程共享该对象,}
   pchar('Map Name')
    );
  if (hMapping = 0) then
  begin
    ShowMessage('不能创建内存映射文件');
    Application.Terminate;
    exit;
  end;
   {将文件数据映射到进程的地址空间}
   {当创建了一个文件映射对象之后,仍然必须让系统为文件的数据保留
    一个地址空间区域,并将文件的数据作为映射到该区域的物理存储器进行提交。
    }
  PShare := PShareMem(MapViewOfFile(HMapping, FILE_MAP_ALL_ACCESS, 0, 0, 0));
  if PShare = nil then
  begin
    CloseHandle(HMapping);
    ShowMessage('Can''t View Memory Map');
    Application.Terminate;
    exit;
  end;

  {既然我们通过pvFile得到了映象视图的起始地址,那么可以对视图做一些操作了}
end;

procedure CloseMap;
begin
  if PShare <> nil then
    {从进程的地址空间中撤销文件数据的映象}
    UnMapViewOfFile(PShare);
  if HMapping <> 0 then
    CloseHandle(HMapping);
end;

function LockMap: Boolean;
begin
  Result := true;
   {创建互斥对象}
  HMapMutex := CreateMutex(nil, false,
    pchar('MY MUTEX NAME GOES HERE'));
  if HMapMutex = 0 then
  begin
    ShowMessage('不能创建互斥对象');
    Result := false;
  end else begin
    if WaitForSingleObject(HMapMutex, REQUEST_TIMEOUT)
      = WAIT_FAILED then
    begin
      ShowMessage('不能对互斥对象加锁!');
      Result := false;
    end
  end
end;

procedure UnlockMap;
begin
   {关闭文件映射对象和文件对象}
  ReleaseMutex(HMapMutex);
  CloseHandle(HMapMutex);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  str: pchar;
begin
  str := pchar('简单的共享内存的例子');
  CopyMemory(@(pShare^.data), Str, Length(str));
  {发送消息表明有数据}
  PostMessage(FindWindow(nil, 'MyForm'), WM_DATA, 1, 1)
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  UnlockMap;
  CloseMap;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  OpenMap;
  LockMap;
end;

[yuqianyi1974]

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

const
  WM_DATA = WM_USER + 1024;
type
  PShareMem = ^TShareMem;
  TShareMem = record
    Data: array[0..255] of char;
  end;
  TMyForm = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure getShareInfo(var Msg: TMessage); message WM_DATA; {处理WM_DATA}
  end;

var
  MyForm: TMyForm;
  PShare: PShareMem;
  MapHandle: THandle;

implementation

{$R *.DFM}

procedure TMyForm.getShareInfo(var Msg: TMessage); {处理WM_DATA}
begin
  if msg.LParam=1 then {是我们设定的消息参数}
    Memo1.Text := PShare^.Data;
end;

procedure TMyForm.FormCreate(Sender: TObject);
begin
  MapHandle := OpenFileMapping(FILE_MAP_WRITE, {获取完全访问映射文件}
    False, {不可继承的}
    pchar('Map Name')); {映射文件名字}
  if MapHandle = 0 then
  begin
    ShowMessage('不能定位内存映射文件块!');
    Halt;
  end;
  PShare := PShareMem(MapViewOfFile(MapHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0));
  if PShare = nil then
  begin
    CloseHandle(MapHandle);
    ShowMessage('Can''t View Memory Map');
    Application.Terminate;
    exit;
  end;
  FillChar(PShare^, SizeOf(TShareMem), 0);
end;

procedure TMyForm.Button1Click(Sender: TObject);
begin
  CloseHandle(MapHandle);
  close;
end;

end.

[yuqianyi1974]

2楼和3楼是两个exe间共享数据的代码，exe和dll间共享数据差不多

[Reverse.King]

[Quote=引用 4 楼 yuqianyi1974 的回复:]
2楼和3楼是两个exe间共享数据的代码，exe和dll间共享数据差不多
[/Quote]
MAP映射文件不仅限于EXE和EXE之间,应该说是进程间的通讯共享.不同进程的EXE和DLL均能访问

[Reverse.King]

但如果用于直接对象共享访问好象不行.因为你无法控制对象整个代码刚好在这个共享区.
用COM,或者改下思路另想它法.

[okmnji79513]

mark 学习

[Harryfin]

首先问一下，内存映射可以映射复杂对象类型吗？因为楼主问的是TClientDataSet共享。

然后，我觉得楼主应该把这个DataSet做在一个BPL里面，就可以做到EXE跟DLL的共享了。

[searphchen]

学习中~~~

[YFLK]

这种方式对于静态数据应该可以，但对于动态数据如何保证两个EXE之间的数据同步。这是关键！！