求内存映射文件的例子(100分)

clyin · 2000-11-07

Delphi,C,CBB均可。

lml · 2000-11-07

这是Delphi的 var   Form1: TForm1;   Data: Pointer;           // holds a pointer to the memory mapped file   hMapping: THandle;       // holds a handle to the memory mapped file object implementation function OpenMappedFile(FileName: string; var FileSize: DWORD): Boolean; var   hFile: THandle;       // a handle to the opened file   HighSize: DWORD;      // the high order double word of the file size begin   {initialize the result of the function in case of errors}   Result := FALSE;   {if no filename was specified, exit}   if Length(FileName)= 0 then Exit;   {open the file for reading and writing. indicate a    sequential scan access for better optimization}   hFile := CreateFile(PChar(FileName), GENERIC_READ or GENERIC_WRITE,                       FILE_SHARE_READ, nil, OPEN_EXISTING,                       FILE_FLAG_SEQUENTIAL_SCAN, 0);   {if the file was not opened, exit;}   if hFile = INVALID_HANDLE_VALUE then Exit;   {retrieve the size of the file}   FileSize := GetFileSize(hFile, @HighSize);   {create a read/write mapping of the opened file}   hMapping:=CreateFileMapping(hFile, nil, PAGE_READWRITE, 0, 0,                               'Delphi File Mapping Example');   {if the file mapping failed, exit}   if (hMapping = 0) then   begin     CloseHandle(hFile);     Exit;   end;   {close the file handle, as we no longer need it}   CloseHandle(hFile);   {map a view of the file}   Data := MapViewOfFile(hMapping, FILE_MAP_WRITE, 0, 0, 0);   {if a view of the file was not created, exit}   if (Data=nil) then Exit;   {to insure that the file's data can be displayed directly as    a string, set the very last byte in the file data to a null terminator}   PChar(Data)[FileSize] := #0;   {the file was successfully opened and mapped}   Result := TRUE; end; function OpenPreviousMappedFile(var FileSize: Integer): Boolean; begin   {initialize the result of the function incase of errors}   Result := FALSE;   {open an existing file mapping}   hMapping := OpenFileMapping(FILE_MAP_WRITE, FALSE,                               'Delphi File Mapping Example');   {if there was an error opening the existing file mapping, exit}   if hMapping=0 then Exit;   {map a view of the file}   Data := MapViewOfFile(hMapping, FILE_MAP_WRITE, 0, 0, 0);   {if a view of the file was not created, exit}   if (Data=nil) then Exit;   {retrieve the length of the data (which can be represented as a null    terminated string due to adding the null terminator to the end when    the file was opened}   FileSize := StrLen(PChar(Data));   {indicate that the file was successfully opened and mapped}   Result := TRUE; end; procedure DisplayMappedFile(FileName: string; Size: Integer); var   Index: Integer;      // general loop counter   DataPtr: PChar;      // a pointer to the mapped file data   HexString: PChar;    // a pointer to a concatenated hexadecimal string begin   {display the name of the mapped file}   Form1.StatusBar1.SimpleText := FileName;   {allocate memory for the hexadecimal representation of the file,    and initialize it to zeros}   GetMem(HexString,Size * 3);   ZeroMemory(HexString, Size*3);   {set the pointer to the beginning of the mapped file data}   DataPtr := Data;   {begin looping through the data}   Index:=0;   while (Index < Size) do   begin     {display the value of each byte in the file as a hexadecimal number}     StrCat(HexString, PChar(IntToHex(Byte(DataPtr[Index]),2)+ ' '));     Inc(Index);   end;   {display the hexadecimal representation of the data and the ASCII    representation of the data}   SetWindowText(Form1.Memo1.Handle,HexString);   SetWindowText(Form1.Memo2.Handle,PChar(Data));   {free the memory for the hexadecimal string}   FreeMem(HexString, Size * 3); end; procedure TForm1.Button1Click(Sender: TObject); var   Size: Integer;     // holds the size of the memory mapped file begin   {open an existing file...}   if OpenDialog1.Execute then   begin     {...map the file...}     OpenMappedFile(OpenDialog1.FileName, Size);     {...and display the memory mapped file}     DisplayMappedFile(OpenDialog1.FileName, Size);   end; end; procedure TForm1.Button3Click(Sender: TObject); var   Size: Integer;     // holds the size of the memory mapped file begin   {open a previously mapped file...}   if OpenPreviousMappedFile(Size) then     {...and display it}     DisplayMappedFile('Existing mapped file', Size); end; procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction); begin   {write any changes to the file}   FlushViewOfFile(Data, 0);     {unmap the view of the file}   if not UnMapViewOfFile(Data) then ShowMessage('Can not unmap file');   {close the mapped file handle}   if not CloseHandle(hMapping) then ShowMessage('Can not Close File'); end;

clyin · 2000-11-20

接受答案了.

求内存映射文件的例子(100分)

clyin

Unregistered / Unconfirmed

lml

Unregistered / Unconfirmed

clyin

Unregistered / Unconfirmed

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