Delphi内存映射文件例子

Delphi内存映射文件例子 收藏
unit FileMap;

interface

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

type
TFileMap=class(TComponent)
private
FMapHandle:THandle; //内存映射文件句柄
FMutexHandle:THandle; //互斥句柄
FMapName:string; //内存映射对象
FSynchMessage:string; //同步消息
FMapStrings:TStringList; //存储映射文件信息
FSize:DWord; //映射文件大小
FMessageID:DWord; //注册的消息号
FMapPointer:PChar; //映射文件的数据区指针
FLocked:Boolean; //锁定
FIsMapOpen:Boolean; //文件是否打开
FExistsAlready:Boolean; //是否已经建立过映射文件
FReading:Boolean; //是否正在读取内存文件数据
FAutoSynch:Boolean; //是否同步
FOnChange:TNotifyEvent; //当内存数据区内容改变时
FFormHandle:Hwnd; //存储本窗口的窗口句柄
FPNewWndHandler:Pointer;
FPOldWndHandler:Pointer;
procedure SetMapName(Value:string);
procedure SetMapStrings(Value:TStringList);
procedure SetSize(Value:DWord);
procedure SetAutoSynch(Value:Boolean);
procedure EnterCriticalSection;
procedure LeaveCriticalSection;
procedure MapStringsChange(Sender:TObject);
procedure NewWndProc(var FMessage:TMessage);
public
constructor Create(AOwner:TComponent);override;
destructor Destroy;override;
procedure OpenMap;
procedure CloseMap;
procedure ReadMap;
procedure WriteMap;
property ExistsAlready:Boolean read FExistsAlready;
property IsMapOpen:Boolean read FIsMapOpen;
published
property MaxSize:DWord read FSize write SetSize;
property AutoSynchronize:Boolean read FAutoSynch write SetAutoSynch;
property MapName:string read FMapName write SetMapName;
property MapStrings:TStringList read FMapStrings write SetMapStrings;
property OnChange:TNotifyEvent read FOnChange write FOnChange;
end;
implementation
constructor TFileMap.Create(AOwner:TComponent);
begin
inherited Create(AOwner);
FAutoSynch:=True;
FSize:=4096;
FReading:=False;
FMapStrings:=TStringList.Create;
FMapStrings.OnChange:=MapStringsChange;
FMapName:='Unique & Common name';
FSynchMessage:=FMapName+'Synch-Now';
if AOwner is TForm then
begin
FFormHandle:=(AOwner as TForm).Handle;
FPOldWndHandler:=

Ptr(GetWindowLong(FFormHandle,GWL_wNDPROC));
FPNewWndHandler:=MakeObjectInstance(NewWndProc);
if FPNewWndHandler=nil then
raise Exception.Create('超出资源');
SetWindowLong(FFormHandle,GWL_WNDPROC,Longint(FPNewWndHandler));
end
else raise Exception.Create('组件的所有者应该是TForm');
end;
destructor TFileMap.Destroy;
begin
CloseMap;
SetWindowLong(FFormHandle,GWL_WNDPROC,Longint(FPOldWndHandler));
if FPNewWndHandler<>nil then
FreeObjectInstance(FPNewWndHandler);
FMapStrings.Free;
FMapStrings:=nil;
inherited destroy;
end;
procedure TFileMap.OpenMap;
var
TempMessage:array[0..255] of Char;
begin
if (FMapHandle=0) and (FMapPointer=nil) then
begin
FExistsAlready:=False;
FMapHandle:=CreateFileMapping($FFFFFFFF,nil,PAGE_READWRITE,0,FSize,PChar(FMapName));
if (FMapHandle=INVALID_HANDLE_VALUE) or (FMapHandle=0) then
raise Exception.Create('创建文件映射对象失败!')
else
begin
if (FMapHandle<>0) and (GetLastError=ERROR_ALREADY_EXISTS) then
FExistsAlready:=True; //如果已经建立的话，就设它为TRUE；
FMapPointer:=MapViewOfFile(FMapHandle,FILE_MAP_ALL_ACCESS,0,0,0);
if FMapPointer=nil then
raise Exception.Create('映射文件的视图到进程的地址空间失败')
else
begin
StrPCopy(TempMessage,FSynchMessage);
FMessageID:=RegisterWindowMessage(TempMessage);
if FMessageID=0 then
raise Exception.Create('注册消息失败')
end
end;
FMutexHandle:=Windows.CreateMutex(nil,False,PChar(FMapName+'.Mtx'));
if FMutexHandle=0 then
raise Exception.Create('创建互斥对象失败');
FIsMapOpen:=True;
if FExistsAlready then //判断内存文件映射是否已打开
ReadMap
else
WriteMap;
end;
end;
procedure TFileMap.CloseMap;
begin
if FIsMapOpen then
begin
if FMutexHandle<>0 then
begin
CloseHandle(FMutexHandle);
FMutexHandle:=0;
end;
if FMapPointer<>nil then
begin
UnMapViewOfFile(FMapPointer);
FMapPointer:=nil;
end;
if FMapHandle<>0 then
begin
CloseHandle(FMapHandle);
FMapHandle:=0;
end;
FIsMapOpen:=False;
end;
end;
procedure TFileMap.ReadMap;
begin
FReading:=True;
if(FMapPointer<>nil) then FMapStrings.SetText(FMapPointer);
end;
procedure TFileMap.WriteMap;
var
StringsPointer:PChar;
HandleCounter:integer;
SendToHandle:HWnd;
begin

if FMapPointer<>nil then
begin
StringsPointer:=FMapStrings.GetText;
EnterCriticalSection;
if StrLen(StringsPointer)+1<=FSize
then System.Move(StringsPointer^,FMapPointer^,StrLen(StringsPointer)+1)
else
raise Exception.Create('写字符串失败，字符串太大！');
LeaveCriticalSection;
SendMessage(HWND_BROADCAST,FMessageID,FFormHandle,0);
StrDispose(StringsPointer);
end;
end;
procedure TFileMap.MapStringsChange(Sender:TObject);
begin
if FReading and Assigned(FOnChange) then
FOnChange(Self)
else if (not FReading) and FIsMapOpen and FAutoSynch then
WriteMap;
end;
procedure TFileMap.SetMapName(Value:string);
begin
if (FMapName<>Value) and (FMapHandle=0) and (Length(Value)<246) then
begin
FMapName:=Value;
FSynchMessage:=FMapName+'Synch-Now';
end;
end;
procedure TFileMap.SetMapStrings(Value:TStringList);
begin
if Value.Text<>FMapStrings.Text then
begin
if Length(Value.Text)<=FSize then
FMapStrings.Assign(Value)
else
raise Exception.Create('写入值太大');
end;
end;
procedure TFileMap.SetSize(Value:DWord);
var
StringsPointer:PChar;
begin
if (FSize<>Value) and (FMapHandle=0) then
begin
StringsPointer:=FMapStrings.GetText;
if (ValueFSize:=StrLen(StringsPointer)+1
else FSize:=Value;
if FSize<32 then FSize:=32;
StrDispose(StringsPointer);
end;
end;
procedure TFileMap.SetAutoSynch(Value:Boolean);
begin
if FAutoSynch<>Value then
begin
FAutoSynch:=Value;
if FAutoSynch and FIsMapOpen then WriteMap;
end;
end;
procedure TFileMap.EnterCriticalSection;
begin
if (FMutexHandle<>0) and not FLocked then
begin
FLocked:=(WaitForSingleObject(FMutexHandle,INFINITE)=WAIT_OBJECT_0);
end;
end;
procedure TFileMap.LeaveCriticalSection;
begin
if (FMutexHandle<>0) and FLocked then
begin
ReleaseMutex(FMutexHandle);
FLocked:=False;
end;
end;
//消息捕获过程
procedure TFileMap.NewWndProc(var FMessage:TMessage);
begin
with FMessage do
begin
if FIsMapOpen
if (Msg=FMessageID) and (WParam<>FFormHandle) then
ReadMap;
Result:=CallWindowProc(FPOldWndHandler,FFormHandle,Msg,wParam,lParam);
end;
end;


end.