ftputil 下载图片工具类

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import java.io.*;

public class FtpUtils {

    private static final Logger logger = LoggerFactory.getLogger(FtpUtils.class);

    private static FTPClient ftpClient;

    /**
     *@Description ftp登录
     *@Param [ftpHost, ftpUserName, ftpPassword, ftpPort]
     *@return org.apache.commons.net.ftp.FTPClient
     **/
    public static FTPClient getFTPCLient(String ftpHost,String ftpUserName,String ftpPassword,int ftpPort){
        try{
            ftpClient = new FTPClient();
            //连接FTP服务器
            ftpClient.connect(ftpHost,ftpPort);
            //登录FTP服务器
            ftpClient.login(ftpUserName,ftpPassword);
            //设置编码格式(支持中文)
//            ftpClient.setControlEncoding("UTF-8");
            //设置传输格式为二进制
            ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
            ftpClient.enterLocalPassiveMode();
            if(!FTPReply.isPositiveCompletion(ftpClient.getReplyCode())){
                logger.error("未连接到FTP，用户名或密码错误");
                ftpClient.disconnect();
            }else{
                logger.info("FTP连接成功");
            }
        }catch(Exception e){
            logger.error(HikLog.toLog("ftp connect error",e);
        }
        return ftpClient;
    }

    /**
     *@Description 判断ftp是否连接成功
     *@Param []
     *@return boolean
     **/
    public static boolean isConnect(){
        if (ftpClient!=null && ftpClient.isConnected()){
            return FTPReply.isPositiveCompletion(ftpClient.getReplyCode());
        }else{
            logger.info("ftp连接断开");
            return false;
        }
    }

    /**
     *@Description 关闭ftp连接
     *@Param []
     *@return void
     **/
    public static void close(){

        if (ftpClient!=null && ftpClient.isConnected()){
            try{
                ftpClient.logout();
                ftpClient.disconnect();
            }catch(Exception e){
                logger.error("ftp close error",e);
            }
        }
    }

    /**
     *@Description 检查文件是否存在
     *@Param [ftpPath]
     *@return boolean
     **/
    public static boolean isFileExist(String ftpPath){
        boolean result = true;
        try{
            ftpClient.listFiles(ftpPath);
        }catch(Exception e){
            result = false;
           logger.error("check file error",e);
        }
        return result;
    }

    /**
     *@Description 从ftp上下载图片
     *@Param [filePath, fileName]
     *@return java.lang.String
     **/
    public static String downloadPic(String filePath,String fileName) {

        InputStream is = null;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] data = null;
        String picBASE64 = "";
        if (isFileExist(filePath)){
            try{
                ftpClient.changeToParentDirectory();

                ftpClient.changeWorkingDirectory(filePath);
                is = ftpClient.retrieveFileStream(fileName);
//                程序运行在windows操作系统，下载的文件名称有中文时，可以用下面的两行代码
//                ftpClient.changeWorkingDirectory(new String(filePath.getBytes("UTF-8"),"iso-8859-1"));
//                is = ftpClient.retrieveFileStream(new String(fileName.getBytes("UTF-8"),"iso-8859-1"));
                byte[] buffer = new byte[1024];
                int n = 0;
                if (is!=null){
                    while(-1 != (n = is.read(buffer))){
                        baos.write(buffer,0,n);
                    }
                    data = baos.toByteArray();
                    BASE64Encoder encoder = new BASE64Encoder();
                    picBASE64 = encoder.encode(data);
                    is.close();
                }else{
                    logger.error("ftp获取文件流失败",e);
                }
            }catch(Exception e){
                logger.error("download error",e);
            }
        }
        return picBASE64;
    }
}