使用JAVA API从FTP服务器下载文件

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import sun.net.TelnetInputStream;
import sun.net.ftp.FtpClient;

public class FtpDownload extends HttpServlet {
 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
   throws ServletException, IOException {
   doPost(req, resp);
 }

 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
   throws ServletException, IOException {
  String ftpServer = "ftp server ip address";
  String username = "username";
  String password = "password";
  String filename = "filename";
  String path = "/path";
  FtpClient ftpClient = new FtpClient();
  ftpClient.openServer(ftpServer);
  ftpClient.login(username, password);
  if (path.length() != 0)
   ftpClient.cd(path);
  ftpClient.binary();
  TelnetInputStream is = ftpClient.get(filename);

  resp.setContentType("application/x-msdownload");
  resp.setHeader("Content-Disposition", (new StringBuilder(
    "attachment;filename=")).append(
    new String(filename.getBytes(), "ISO-8859-1")).toString());

  ServletOutputStream out = resp.getOutputStream();
  byte[] bytes = new byte[1048576];
  int c;
  while ((c = is.read(bytes)) != -1) {
   out.write(bytes, 0, c);
  }
  is.close();
  out.flush();
  out.close();
  ftpClient.closeServer();
 }

}