unit1.~pas

本实例解决从C#中导出文件

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    T1: TMemo;
    T2: TMemo;
    procedure Button1Click(Sender: TObject);
  private
     function EncodeBase64(Source:string):string;
    // function DecodeBase64(Source:string):string;
    // function FindInTable(CSource:char):integer;

     { Private declarations }

  public
    { Public declarations }
  end;
    //   const  //BaseTable为BASE64码表
    // BaseTable:string='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  str:string;
begin
 str:=DecodeBase64(t1.Text);
 //密钥，自行设定
t2.Text:=DESryStr(str,'AAAAAAAA');
end;

{function TForm1.DecodeBase64(Source: string): string;
var
  SrcLen,Times,i:integer;
  x1,x2,x3,x4,xt:byte;
begin
  result:='';
  SrcLen:=Length(Source);
  Times:=SrcLen div 4;
  for i:=0 to Times-1 do
  begin
    x1:=FindInTable(Source[1+i*4]);
    x2:=FindInTable(Source[2+i*4]);
    x3:=FindInTable(Source[3+i*4]);
    x4:=FindInTable(Source[4+i*4]);
    x1:=x1 shl 2;
    xt:=x2 shr 4;
    x1:=x1 or xt;
    x2:=x2 shl 4;
    result:=result+chr(x1);
    if x3= 64 then break;
    xt:=x3 shr 2;
    x2:=x2 or xt;
    x3:=x3 shl 6;
    result:=result+chr(x2);
    if x4=64 then break;
    x3:=x3 or x4;
    result:=result+chr(x3);
  end;

end; }

function TForm1.EncodeBase64(Source: string): string;
var
  Times,LenSrc,i:integer;
  x1,x2,x3,x4:char;
  xt:byte;
begin
  result:='';
  LenSrc:=length(Source);
  if LenSrc mod 3 =0 then Times:=LenSrc div 3
  else Times:=LenSrc div 3 + 1;
  for i:=0 to times-1 do
  begin
    if LenSrc >= (3+i*3) then
    begin
      x1:=BaseTable[(ord(Source[1+i*3]) shr 2)+1];
      xt:=(ord(Source[1+i*3]) shl 4) and 48;
      xt:=xt or (ord(Source[2+i*3]) shr 4);
      x2:=BaseTable[xt+1];
      xt:=(Ord(Source[2+i*3]) shl 2) and 60;
      xt:=xt or (ord(Source[3+i*3]) shr 6);
      x3:=BaseTable[xt+1];
      xt:=(ord(Source[3+i*3]) and 63);
      x4:=BaseTable[xt+1];
    end
    else if LenSrc>=(2+i*3) then
    begin
      x1:=BaseTable[(ord(Source[1+i*3]) shr 2)+1];
      xt:=(ord(Source[1+i*3]) shl 4) and 48;
      xt:=xt or (ord(Source[2+i*3]) shr 4);
      x2:=BaseTable[xt+1];
      xt:=(ord(Source[2+i*3]) shl 2) and 60;
      x3:=BaseTable[xt+1];
      x4:='=';
    end else
    begin
      x1:=BaseTable[(ord(Source[1+i*3]) shr 2)+1];
      xt:=(ord(Source[1+i*3]) shl 4) and 48;
      x2:=BaseTable[xt+1];
      x3:='=';
      x4:='=';
    end;
    result:=result+x1+x2+x3+x4;
  end;

end;

{function TForm1.FindInTable(CSource: char): integer;
begin
result:=Pos(string(CSource),BaseTable)-1;
end;}

end.