为什么我不能将FTP客户端连接到服务器？

Question

我制作了一个FTP客户端（被动），它无法连接到服务器。我使用的FTP服务器是Filezilla；我只是用它来测试。每次我运行java程序（FTP客户端）时，Filezilla都会断开连接，并在Eclipse中出现以下错误：线程“main”java中出现异常。木卫一。IOException:SimpleFTP在连接到FTP服务器时收到未知响应：220 FileZilla服务器0.9.50 beta版在FTP上。ftp。通过ftp连接（ftp.java:25）。测验main（test.java:12）

这是FTP客户端：

package ftp;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;

public class ftp
{

 public synchronized void connect(String host, int port, String user,
          String pass) throws IOException {
    Socket socket = new Socket(host, port);
    //  if (socket != null) {
     //     throw new IOException("SimpleFTP is already connected. Disconnect first.");
     //   }
      //  socket = new Socket(host, port);
        BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        BufferedWriter writer = new BufferedWriter(
            new OutputStreamWriter(socket.getOutputStream()));

        String response = reader.readLine();
        if (!response.startsWith("220-")) {
          throw new IOException(
              "SimpleFTP received an unknown response when connecting to the FTP server: "
                  + response);
        } else System.out.println("1:"+response);

        writer.write("user geek"+"\r\n");
        writer.flush();
        response= reader.readLine();
        System.out.println("2"+response);
       // response = reader.readLine();
      /*  if (!response.startsWith("331 ")) {
          throw new IOException(
              "SimpleFTP received an unknown response after sending the user: "
                  + response);
        }
        else {*/
        writer.write("PASS hello" +"\r\n");
        writer.flush();
            response= reader.readLine();
            System.out.println("3"+response);
        //}


        response = reader.readLine();
        /*if (!response.startsWith("230 ")) {
          throw new IOException(
              "SimpleFTP was unable to log in with the supplied password: "
                  + response);
        }
        else {*/
            System.out.println("4"+response);
        //}
 }

}

这是我连接的程序：

package ftp;

import java.util.Scanner;

public class test {
 private static Scanner scan;

public static void main(String args[]) throws Exception
    {

        ftp s = new ftp();
            s.connect("localhost",21,"geek", "hello");

    }

}

还尝试编写我的lan ip而不是“localhost”

Answer 1

... 220 FileZilla服务器版本0.9.50测试版

if (!response.startsWith("220 ")) {

您希望得到以220开头的响应