ftp上传文件，在最后一步保存文件时失败，代码如下：
ftpc.storeFile(fileName, fis);
执行结果总是失败
    public boolean uploadFile(String fileName, FileInputStream fis)
    {
        FTPClient ftpc = new FTPClient();
        try
        {
            // 连接
            ftpc.connect(this.getHostName(), this.getHostPort());
            
            int reply = ftpc.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply))
            {
                ftpc.disconnect();
                logger.error("FTP server refused connection.");
                return false;
            }
            
            // 登录及目录切换
            ftpc.login(this.getUsername(), this.getPassword());
            boolean isChageDirSucess1 = ftpc.changeWorkingDirectory(this.getRemoteDir());
            System.out.println(isChageDirSucess1);
            // 目录检查
            String dirName = this.getSavePath().substring(1);
            boolean isChageDirSucess = ftpc.changeWorkingDirectory(dirName);
            System.out.println(isChageDirSucess);
            ftpc.setFileType(FTP.ASCII_FILE_TYPE);
            if (isChageDirSucess)
            {
                boolean ff = ftpc.storeFile(fileName, fis);
                System.out.println(ff);
            }
            else
            {
                boolean flag = ftpc.makeDirectory(dirName);
                if (flag)
                {
                    logger.info("make Directory " + this.getSavePath() + " succeed");
                }
                else
                {
                    logger.info("make Directory " + this.getSavePath() + " false");
                    return false;
                }
                ftpc.changeWorkingDirectory(dirName);
                ftpc.storeFile(fileName, fis);
            }