Присоединиться к FTP серверу и загрузить с него файл

{ 
  The following function shows how to connect to a ftp server 
  and download a file. 
  It uses the functions from wininet.dll. 

  You need a ProgressBar to show the progress and a Label to show progress informations. 
} 

uses 
  WinInet, ComCtrls; 

function FtpDownloadFile(strHost, strUser, strPwd: string; 
  Port: Integer; ftpDir, ftpFile, TargetFile: string; ProgressBar: TProgressBar): Boolean; 

  function FmtFileSize(Size: Integer): string; 
  begin 
    if Size >= $F4240 then 
      Result := Format('%.2f', [Size / $F4240]) + ' Mb' 
    else 
    if Size < 1000 then 
      Result := IntToStr(Size) + ' bytes' 
    else 
      Result := Format('%.2f', [Size / 1000]) + ' Kb'; 
  end; 

const 
  READ_BUFFERSIZE = 4096;  // or 256, 512, ... 
var 
  hNet, hFTP, hFile: HINTERNET; 
  buffer: array[0..READ_BUFFERSIZE - 1] of Char; 
  bufsize, dwBytesRead, fileSize: DWORD; 
  sRec: TWin32FindData; 
  strStatus: string; 
  LocalFile: file; 
  bSuccess: Boolean; 
begin 
  Result := False; 

  { Open an internet session } 
  hNet := InternetOpen('Program_Name', // Agent 
                        INTERNET_OPEN_TYPE_PRECONFIG, // AccessType 
                        nil,  // ProxyName 
                        nil, // ProxyBypass 
                        0); // or INTERNET_FLAG_ASYNC / INTERNET_FLAG_OFFLINE 

  { 
    Agent contains the name of the application or 
    entity calling the Internet functions 
  } 


  { See if connection handle is valid } 
  if hNet = nil then 
  begin 
    ShowMessage('Unable to get access to WinInet.Dll'); 
    Exit; 
  end; 

  { Connect to the FTP Server } 
  hFTP := InternetConnect(hNet, // Handle from InternetOpen 
                          PChar(strHost), // FTP server 
                          port, // (INTERNET_DEFAULT_FTP_PORT), 
                          PChar(StrUser), // username 
                          PChar(strPwd),  // password 
                          INTERNET_SERVICE_FTP, // FTP, HTTP, or Gopher? 
                          0, // flag: 0 or INTERNET_FLAG_PASSIVE 
                          0);// User defined number for callback 

  if hFTP = nil then 
  begin 
    InternetCloseHandle(hNet); 
    ShowMessage(Format('Host "%s" is not available',[strHost])); 
    Exit; 
  end; 

  { Change directory } 
  bSuccess := FtpSetCurrentDirectory(hFTP, PChar(ftpDir)); 

  if not bSuccess then 
  begin 
    InternetCloseHandle(hFTP); 
    InternetCloseHandle(hNet); 
    ShowMessage(Format('Cannot set directory to %s.',[ftpDir])); 
    Exit; 
  end; 

  { Read size of file } 
  if FtpFindFirstFile(hFTP, PChar(ftpFile), sRec, 0, 0) <> nil then 
  begin 
    fileSize := sRec.nFileSizeLow; 
    // fileLastWritetime := sRec.lastWriteTime 
  end else 
  begin 
    InternetCloseHandle(hFTP); 
    InternetCloseHandle(hNet); 
    ShowMessage(Format('Cannot find file ',[ftpFile])); 
    Exit; 
  end; 

  { Open the file } 
  hFile := FtpOpenFile(hFTP, // Handle to the ftp session 
                       PChar(ftpFile), // filename 
                       GENERIC_READ, // dwAccess 
                       FTP_TRANSFER_TYPE_BINARY, // dwFlags 
                       0); // This is the context used for callbacks. 

  if hFile = nil then 
  begin 
    InternetCloseHandle(hFTP); 
    InternetCloseHandle(hNet); 
    Exit; 
  end; 

  { Create a new local file } 
  AssignFile(LocalFile, TargetFile); 
  {$i-} 
  Rewrite(LocalFile, 1); 
  {$i+} 

  if IOResult <> 0 then 
  begin 
    InternetCloseHandle(hFile); 
    InternetCloseHandle(hFTP); 
    InternetCloseHandle(hNet); 
    Exit; 
  end; 

  dwBytesRead := 0; 
  bufsize := READ_BUFFERSIZE; 

  while (bufsize > 0) do 
  begin 
    Application.ProcessMessages; 

    if not InternetReadFile(hFile, 
                            @buffer, // address of a buffer that receives the data 
                            READ_BUFFERSIZE, // number of bytes to read from the file 
                            bufsize) then Break; // receives the actual number of bytes read 

    if (bufsize > 0) and (bufsize <= READ_BUFFERSIZE) then 
      BlockWrite(LocalFile, buffer, bufsize); 
    dwBytesRead := dwBytesRead + bufsize; 

    { Show Progress } 
    ProgressBar.Position := Round(dwBytesRead * 100 / fileSize); 
    Form1.Label1.Caption := Format('%s of %s / %d %%',[FmtFileSize(dwBytesRead),FmtFileSize(fileSize) ,ProgressBar.Position]); 
  end; 

  CloseFile(LocalFile); 

  InternetCloseHandle(hFile); 
  InternetCloseHandle(hFTP); 
  InternetCloseHandle(hNet); 
  Result := True; 
end;