[NumLock]

Код:

unit Unit1;

interface

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

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

var
  Form1: TForm1;

implementation

{$R *.dfm}

function GetTempPath: String;
var
  buf: array [0..255] of Char;
  l: Integer;
begin
  l:=Windows.GetTempPath(SizeOf(buf), @buf);
  if l>0 then Result:=Copy(buf, 0, l) else Result:='';
  Result:=IncludeTrailingPathDelimiter(Result);
end;

function GetInternetFile(const AURL: String; AFileName: String): Boolean;
var
  hInternet: Pointer;
  hOpenUrl: Pointer;
  data: array [0..$ffff] of Byte;
  dummy: Cardinal;
  filestream: TFileStream;
begin
  Result:=False;
  hInternet:=nil;
  hOpenUrl:=nil;
  try
    hInternet:=InternetOpen('Mozilla/4.0', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
    if hInternet=nil then raise Exception.Create('InternetOpen: '+SysErrorMessage(GetLastError));
    hOpenUrl:=InternetOpenUrl(hInternet, PChar(AURL), nil, 0, INTERNET_FLAG_NO_COOKIES or INTERNET_FLAG_RELOAD or INTERNET_FLAG_PRAGMA_NOCACHE, 0);
    if hOpenUrl=nil then raise Exception.Create('InternetOpenUrl: '+SysErrorMessage(GetLastError));
    filestream:=TFileStream.Create(AFileName, fmCreate);
    try
      while InternetReadFile(hOpenUrl, @data[0], $10000, dummy) do
        if dummy>0 then filestream.Write(data, dummy) else Break;
      Result:=True;
    finally
      filestream.Free;
    end;
  finally
    if hOpenUrl<>nil then InternetCloseHandle(hOpenUrl);
    if hInternet<>nil then InternetCloseHandle(hInternet);
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if not GetInternetFile('http://download.microsoft.com/download/5/6/7/567758a3-759e-473e-bf8f-52154438565a/dotnetfx.exe',
    GetTempPath+'dotnetfx.exe') then ShowMessage('oops');
end;

end.