delphi 快速读取文件然后用TPerlRegEx类提取需要内容

本文介绍了如何在Delphi中快速读取文件内容，并利用TPerlRegEx类进行字符串匹配和提取所需信息，适用于需要处理大量文本数据的场景。

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unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    Edit1: TEdit;
    Edit2: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function MMFileToString(const AFilename: string): string;
var
  hFile: THandle;
  hFileMap: THandle;
  hiSize: DWORD;
  loSize: DWORD;
  text: string;
  view: pointer;
begin
  Result := '';
  if AFilename = '' then
    Exit;
  if not FileExists(AFilename) then
    Exit;
  {Open the file}
  hFile := CreateFile(PChar(AFilename), GENERIC_READ, FILE_SHARE_READ, nil,
    OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if hFile <> INVALID_HANDLE_VALUE then
  begin
    loSize := GetFileSize(hFile, @hiSize);
    {File was opened successfully, now map it:}
    hFileMap := CreateFileMapping(hFile, nil, PAGE_READONLY, hiSize,
   loSize, 'TextForString');
    if (hFileMap <> 0) then
    begin
      if (GetLastError() = ERROR_ALREADY_EXISTS) then
      begin
        MessageDlg('Mapping already exists - not created.', mtWarning, [mbOk], 0);
        CloseHandle(hFileMap)
      end
      else
      begin
        try
          {File mapped successfully, now map a view of the file into 
     the address space:}
          view := MapViewOfFile(hFileMap, FILE_MAP_READ, 0, 0, 0);
          if (view <> nil) then
          begin {View mapped successfully}
            CloseHandle(hFile); 
      {Close file handle - as long is view is open it will persist}
            SetLength(Result, loSize);
            Move(view^, Result[1], loSize);
          end
          else
            MessageDlg('Unable to map view of file. ' + SysErrorMessage(GetLastError),
              mtWarning, [mbOk], 0);
        finally
          UnmapViewOfFile(view); {Close view}
          CloseHandle(hFileMap); {Close mapping}
        end
      end
    end
    else
    begin
      MessageDlg('Unable to create file mapping. ' + SysErrorMessage(GetLastError),
        mtWarning, [mbOk], 0);
    end;
  end
  else
  begin
    MessageDlg('Unable to open file. ' + SysErrorMessage(GetLastError),
   mtWarning, [mbOk], 0);
  end;
end;



procedure TForm1.Button1Click(Sender: TObject);

var

str:string;
reg: TPerlRegEx;
List: TStrings;


begin

   reg:=TPerlRegEx.Create;
   reg.Subject := MMFileToString(Edit2.Text);
   reg.RegEx   := Edit1.Text;

   while reg.MatchAgain do
     begin
     str:=str+reg.MatchedText+#13#10;
     end;

   Memo1.Text:=str;
   FreeAndNil(reg);
end;



end.