import sun.net.*;
import sun.net.ftp.*;

public class FTP {
    
    public static void main(String[] args) {
     
        String server="192.168.0.12";   //输入的FTP服务器的IP地址
        String user="useway";            //登录FTP服务器的用户名
        String password="!@#$%abce";   //登录FTP服务器的用户名的口令
        String path="/home/useway";      //FTP服务器上的路径
        
        try {
          
          FtpClient ftpClient=new FtpClient();  //创建FtpClient对象
          ftpClient.openServer(server);        //连接FTP服务器
          ftpClient.login(user, password);     //登录FTP服务器
          
          if (path.length()!=0) ftpClient.cd(path);
          
          TelnetInputStream is=ftpClient.list();
          int c;
          while ((c=is.read())!=-1) {
             System.out.print((char)c);
          }
          is.close();
          ftpClient.closeServer();//退出FTP服务器
        }
        catch(Exception ex){
        }
     }
}

import java.io.InputStream;   
import java.io.OutputStream;   
import java.net.Socket;  

public class FTPClient{
    public static void main(String[] args) throws Exception{   
        Socket socket = new Socket("192.168.0.1",21);   
        InputStream is = socket.getInputStream();   
        OutputStream os = socket.getOutputStream();

//接收初始链接信息
        byte[] buffer = new byte[100];
        int length = is.read(buffer);
        String s = new String(buffer, 0, length);
        System.out.println(s);
        //发送用户名
        String str = "USER useway\n";
        os.write(str.getBytes());
        //得到返回值
        length = is.read(buffer);
        s = new String(buffer, 0, length);
        System.out.println(s);        
        //发送密码
        str = "PASS !@#$%abcd\n";
        os.write(str.getBytes());
//得到返回值
        length = is.read(buffer);
        s = new String(buffer, 0, length);
        System.out.println(s);
        //发送切换文件夹指令
        str = "CWD /home/useway\n";
        os.write(str.getBytes());
        //得到返回值
        length = is.read(buffer);
        s = new String(buffer, 0, length);
        System.out.println(s);
        //设置模式
        str = "EPSV ALL\n";
        os.write(str.getBytes());
        //得到返回值
        length = is.read(buffer);
        s = new String(buffer, 0, length);
        System.out.println(s);        
        //得到被动监听信息
        str = "EPSV\n";
        os.write(str.getBytes());
        //得到返回值
        length = is.read(buffer);
        s = new String(buffer, 0, length);
        System.out.println(s);
        //取得FTP被动监听的端口号
        String portlist=s.substring(s.indexOf("(|||")+4,s.indexOf("|)"));
        System.out.println(portlist);
        //实例化ShowList线程类，链接FTP被动监听端口号
        ShowList sl=new ShowList();
        sl.port=Integer.parseInt(portlist);
        sl.start();
        //执行LIST命令
        str = "LIST\n";
        os.write(str.getBytes());
        //得到返回值
        length = is.read(buffer);
        s = new String(buffer, 0, length);
        System.out.println(s); 
        //关闭链接
        is.close();
        os.close();
        socket.close();
    }
}
//得到被动链接信息类，这个类是多线程的
class ShowList extends Thread{
 public int port=0;
    public void run(){
     try{
         Socket socket = new Socket("192.168.0.1",this.port);
         InputStream is = socket.getInputStream();
         OutputStream os = socket.getOutputStream();
         byte[] buffer = new byte[10000];
         int length = is.read(buffer);
         String s = new String(buffer, 0, length);
         System.out.println(s);
            //关闭链接
            is.close();
            os.close();
            socket.close();
     }
     catch(Exception ex){
     }
    }
}