How to use FTP download in java

    /**
     *
     * JAVA操作 FTP 下载
     * 文件下载。
     *
     */
    private void ftpDownload()
    {
        FTPClient ftpClient = null;
        InputStream input = null;
        boolean loginFlag = false;
        List<String> list = new ArrayList<String>();
        try
        {
            int defaultPort = CommonsMessage.FTP_DEFAULT_PORT; // 21
            int timeout = M400Constant.NUM_SIXTY_THOUSAND * M400Constant.NUM_TWO; // 120000
            ftpClient = new FTPClient();
 
            ftpClient.setDefaultPort(defaultPort);
            ftpClient.setConnectTimeout(timeout);
//            ftpClient.setSoTimeout(timeout);
            ftpClient.setDefaultTimeout(timeout);
            ftpClient.setDataTimeout(timeout);
            ftpClient.setControlEncoding("UTF-8");
            FTPClientConfig conf = new FTPClientConfig(FTPClientConfig.SYST_UNIX);
            conf.setServerLanguageCode("en");
            conf.setDefaultDateFormatStr("MMM dd HH:mm");
            ftpClient.configure(conf);
 
            ftpClient.connect(SystemConfig.getKey("scpFtpIp"));
            loginFlag = ftpClient.login(SystemConfig.getKey("scpFtpUserName").trim(),
                    SystemConfig.getKey("scpFtpPassword").trim());
            String ftpDir = SystemConfig.getKey("ftpHangupDir").trim();
            if (!loginFlag)
            {
                DEBUGGER.debug("login scp ftp is :" + loginFlag);
            }
            // String ftpDir = SystemConfig.getKey("ftpHangupDir").trim();
 
            if (ftpClient.changeWorkingDirectory(ftpDir))
            {
                
 
                FTPFile file[] = ftpClient.listFiles(ftpDir);
 
                if (file != null && file.length > 0)
                {
                    DEBUGGER.debug("hungup file size is:  " + file.length);
                    for (int i = 0; i < file.length; i++)
                    {
                        String fileName = file[i].getName();
                        ftpClient.setBufferSize(CommonsMessage.ONE_K_BUFFER_SIZE);
 
                        // 设置文件类型（二进制）
                        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
 
                        input = ftpClient.retrieveFileStream(fileName);
                        processInput(ftpClient, input, list, fileName);
 
                        // if (downFlag) {
                        // ftpClient.deleteFile(fileName);
                        // }
                    }
                }
                else
                {
                    try
                    {
                        Thread.sleep(M400Constant.NUM_FIVE_THOUSAND);
                    }
                    catch (InterruptedException e)
                    {
                        /*
                         * if (DEBUGGER.isDebugEnable()) {
                         * DEBUGGER.debug("Failed to queryScpToQuery", e); }
                         */
                        error("Failed to queryScpToQuery", e);
                    }
                }
 
            }
            else
            {
                DEBUGGER.debug("scp dir is error ");
            }
 
        }
        catch (Exception e)
        {
            /*
             * DEBUGGER.debug("dowonload file is faild  ", e);
             */
            error("dowonload file is faild  ", e);
        }
        finally
        {
            close(input, "close inputStream  is faild  ");
            if (ftpClient != null)
            {
                try
                {
                    deleteFile(ftpClient, list);
                    boolean logoutFlag = false;
                    try
                    {
                        logoutFlag = ftpClient.logout();
                        // DEBUGGER.debug("logout : " + logoutFlag);
                    }
                    catch (Exception e)
                    {
                        /*
                         * DEBUGGER.debug("logout : " + logoutFlag);
                         */
                        error("logout : " + logoutFlag, e);
                    }
                    ftpClient = null;
                }
                catch (Exception e)
                {
                    /*
                     * if (DEBUGGER.isDebugEnable()) {
                     * DEBUGGER.error("Failed to ftpDownload", e); }
                     */
                    error("Failed to ftpDownload", e);
                }
                // try {
                // ftpClient.disconnect();
                // } catch (IOException e) {
                // if (DEBUGGER.isDebugEnable()) {
                // DEBUGGER.debug("Failed to ftpDownload", e);
                // }
                // }
            }
        }
    }
 
    /**
     * 处理ftp对应文件输入流。
     *
     * @param ftpClient
     *            ftp客户端对象
     * @param input
     *            ftp文件输入流
     * @param list
     *            处理完毕的文件列表，用于执行文件删除使用
     * @param fileName
     *            当前处理的文件名称
     */
    private void processInput(FTPClient ftpClient, InputStream input, List<String> list, String fileName)
    {
        if (input == null)
        {
            return;
        }
        // boolean downFlag = callingService(input);
        callingService(input);
        try
        {
            input.close();
            ftpClient.completePendingCommand();
            list.add(fileName);
        }
        catch (Exception e)
        {
            /*
             * DEBUGGER.debug("Failed to ftpDownload", e);
             */
            error("Failed to ftpDownload", e);
        }
    }
}