Util--FtpUtils

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/**
 * 支持断点续传的FTP实用类 
 * 
 * @author chenxin
 * @version [版本号, 2012-5-21]
 * @see [相关类/方法]
 * @since [产品/模块版本]
 */
public class FtpUtils  {

	private FTPClient ftpClient = null;
   private static final Logger logger = Logger.getLogger(FtpUtils.class);
   private String hostname;
   private String username;
   private String password;
   private int port;
   private static final String EPUB_DIR = "epub_file";
   
   public FtpUtils()
   {
       ftpClient = new FTPClient();
       username = ServerConfig.get("ftp/ftp-user", "");
       password = ServerConfig.get("ftp/ftp-password", "");
       hostname = ServerConfig.get("ftp/ftp-host", "");
       port = ServerConfig.getInt("ftp/ftp-port", 21);
//       {   
//           //设置将过程中使用到的命令输出到控制台   
//           ftpClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));   
//       } 
   }  
      
   /**  
    * 连接到FTP服务器 
    * @param hostname 主机名 
    * @param port 端口 
    * @param username 用户名 
    * @param password 密码 
    * @return 是否连接成功 
    * @throws IOException 
    */  
   public boolean connect() throws IOException{  
       ftpClient.connect(hostname, port);   
       ftpClient.setControlEncoding(ServerConfig.get("ftp/ftp-charset", "GBK"));   
       if(FTPReply.isPositiveCompletion(ftpClient.getReplyCode())){   
           if(ftpClient.login(username, password)){  
               // 设置被动模式
               ftpClient.enterLocalPassiveMode();
               // 设置以二进制方式传输
               ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
               return true;   
           }   
       }   
       disconnect();   
       return false;   
   }   
   
   public boolean reconnect() throws IOException
   {  
         disconnect();  
         ftpClient.connect(hostname, port);   
         ftpClient.setControlEncoding(ServerConfig.get("ftp/ftp-charset", "GBK"));   
         if(FTPReply.isPositiveCompletion(ftpClient.getReplyCode())){   
             if(ftpClient.login(username, password)){  
                 // 设置被动模式
                 ftpClient.enterLocalPassiveMode();
                 // 设置以二进制方式传输
                 ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
                 return true;   
             }   
         }   
         disconnect();   
         return false;   
 }   
      
 /**
  * 从FTP服务器上下载文件,上传百分比
  * @param remote
  * @param dir
  * @param fileName
  * @return
  * @throws IOException
  * @see [类、类#方法、类#成员]
  */
    public boolean download(String remote, String dir, String fileName)
        throws IOException
    {
        File file = new File(dir + File.separator + fileName);
        // 本地存在文件
        if (file.exists())
        {
            if (logger.isDebugEnabled())
            {
                logger.debug("File is existsed.");
            }
            // 如果文件存在，但还未从FTP服务器上完全取下来，则需要等待
            Long initialSize = 0L;
            int i = 0;
            while (initialSize != file.length())
            {
                i++;
                initialSize = file.length();
                try
                {
                    Thread.sleep(100L);
                }
                catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
            }
            
            if (i > 1)
            {
                // 如果是刚下完的文件，则不需要再比对大小是否一致
                return true;
            }
        }
        
        Long localSize = file.length();
        File localDir = new File(dir);
        if (!localDir.exists())
        {
            localDir.mkdirs();
        }
        
        // 检查远程文件是否存在
        if (remote.startsWith("/"))
        {
            remote = remote.substring(1);
        }
        
        if (ftpClient.listNames(remote).length <= 0)
        {   
            // 文件不存在
            logger.error("Could not find file from ftp server: " + remote);
            return false;
        }
        
        // 计算远程文件大小
        String s = "SIZE " + remote + "\r\n";
        ftpClient.sendCommand(s);
        String s1 = ftpClient.getReplyString();
        Long remoteSize = Long.parseLong(s1.substring(3).trim());
        if (logger.isDebugEnabled())
        {
            logger.debug("localsize: " + localSize + ", remoteSize: " + remoteSize);
        }
        if (remoteSize.equals(localSize))
        {
            if (logger.isDebugEnabled())
            {
                logger.debug("File's size not changed.");
            }
            return true;
        }
        else if (localSize != 0L)
        {
            if (logger.isDebugEnabled())
            {
                logger.debug("File's size changed which needed re-download.");
            }
            //远程文件和本地文件大小不一致，则删除本地文件
            file.delete();
            //如果是EPUB书路径，则需要把解压过的临时文件也一并删除
            if (dir.indexOf(EPUB_DIR) > 0)
            {
                deleteAll(localDir);
            }
        }
        
        // 重连以回到根目录
        reconnect();
        OutputStream out = new FileOutputStream(file);
        InputStream in = ftpClient.retrieveFileStream(new String(remote.getBytes("UTF-8"),
            ServerConfig.get("ftp/ftp-charset", "GBK")));
        if (logger.isDebugEnabled())
        {
            logger.debug("Begin to downloaded file from ftp.");
        }
        byte[] bytes = new byte[1024];
        int count;
        while ((count = in.read(bytes)) != -1)
        {
            out.write(bytes, 0, count);
        }
        if (logger.isDebugEnabled())
        {
            logger.debug("File has been downloaded from ftp successfully.");
        }
        in.close();
        out.close();
        boolean upNewStatus = ftpClient.completePendingCommand();
        if (upNewStatus)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    
    //递归删除文件夹
    private void deleteAll(File file)
    {
        if (file.isDirectory() && !ArrayUtils.isEmpty(file.list()))
        {
            for (File childFile : file.listFiles())
            {
                deleteAll(childFile);
            }
        }
        else
        {
            file.delete();
        }
    }

    /** *//** 
     * 断开与远程服务器的连接 
     * @throws IOException 
     */  
    public void disconnect() throws IOException{   
        if(ftpClient.isConnected()){   
            ftpClient.disconnect();   
        }   
    }   
       
    public static void main(String[] args) {   
        FtpUtils myFtp = new FtpUtils();   
        try {   
            myFtp.connect();   
            System.out.println(myFtp.download("/央视走西口/新浪网/走西口24.mp4", "E:\\走西口242.mp4", "123"));   
            myFtp.disconnect();   
        } catch (IOException e) {   
            System.out.println("连接FTP出错："+e.getMessage());   
        }   
    } 



        //使用： 下载文件
        FtpUtils ftpUtils = new FtpUtils();
        ftpUtils.connect();
        ftpUtils.download(fileUrl, directoryPath, filename);
        ftpUtils.disconnect();




}