java 实现FTP上传下载功能，并解决Could not parse response code.Server Reply: SSH-2.0-OpenSSH_5.3问题

现有需求将文件从FTP服务器上进行上传下载，看网上使用了org.apache.commons.net.ftp.FTPClient类，但通过该类连接FTP会报一个Could not parse response code.Server Reply: SSH-2.0-OpenSSH_5.3这样的错误，原因是它不支持这种方式的连接(使用FTPSClient的SSL也是不行的)，所以现在换新的工具，使用ChannelSftp来实现该功能。

上代码：根据实际情况略作修改

pom文件：

<dependency>
  <groupId>com.jcraft</groupId>
  <artifactId>jsch</artifactId>
  <version>0.1.54</version>
</dependency>

默认编码是UTF-8 

@Slf4j
@Component
public class FtpJSch {
    /*
    缺关闭连接
     */
    private static ChannelSftp sftp = null;
    private static Channel channel=null;
    private static Session sshSession=null;

    //账号
    private static String user = "";
    //主机ip
    private static String host = "";
    //密码
    private static String password = "";
    //端口
    private static int port = 22;
    //上传地址
    private static String directory = "";
    //下载目录
    private static String saveFile = "";

    public static void getConnect(){
        try {
            JSch jsch = new JSch();
            //获取sshSession 账号-ip-端口
            sshSession =jsch.getSession(user, host,port);
            //添加密码
            sshSession.setPassword(password);
            Properties sshConfig = new Properties();
            //严格主机密钥检查
            sshConfig.put("StrictHostKeyChecking", "no");

            sshSession.setConfig(sshConfig);
            //开启sshSession链接
            sshSession.connect();
            //获取sftp通道
            channel = sshSession.openChannel("sftp");
            //开启
            channel.connect();
            sftp = (ChannelSftp) channel;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     *
     * @param uploadFile 上传文件的路径
     * @return 服务器上文件名
     */
    public String upload(String uploadFile) {
        getConnect();
        File file = null;
        String fileName = null;
        try {
            sftp.cd(directory);
            file = new File(uploadFile);
            //获取随机文件名
            fileName = UUID.randomUUID().toString() + file.getName().substring(file.getName().length()-5);
            //文件名是 随机数加文件名的后5位
            sftp.put(new FileInputStream(file), fileName);
        } catch (Exception e) {
            e.printStackTrace();
        }
        closeChannel(channel);
        closeSession(sshSession);
        return file == null ? null : fileName;
    }

    /**
     * 下载文件
     */
    public void download(String downloadFileName) {
        try {
            getConnect();
            sftp.cd(directory);
            File file = new File(saveFile+File.separator+downloadFileName);
            sftp.get(downloadFileName, new FileOutputStream(file));
            closeChannel(channel);
            closeSession(sshSession);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 删除文件
     *
     * @param deleteFile
     * 要删除的文件名
     */
    public void delete(String deleteFile) {
        try {
            sftp.cd(directory);
            sftp.rm(deleteFile);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 列出目录下的文件
     *
     * 要列出的目录
     * @return
     * @throws SftpException
     */
    public Vector listFiles()
            throws SftpException {
        getConnect();
        Vector ls = sftp.ls(directory);
        closeChannel(channel);
        closeSession(sshSession);
        return ls;
    }
    private static void closeChannel(Channel channel) {
        if (channel != null) {
            if (channel.isConnected()) {
                channel.disconnect();
            }
        }
    }

    private static void closeSession(Session session) {
        if (session != null) {
            if (session.isConnected()) {
                session.disconnect();
            }
        }
    }
}