Java FTP操作

pom引用：

        <dependency>
            <groupId>commons-net</groupId>
            <artifactId>commons-net</artifactId>
            <version>3.6</version>
        </dependency>

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.3.2</version>
        </dependency>

代码：

package com.suncreate.wifi.tool;

import org.apache.commons.io.IOUtils;
import org.apache.commons.net.PrintCommandListener;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.io.*;
import java.util.ArrayList;
import java.util.List;

@Service
public class FtpUtils {

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

    private static final String SEPARATOR_CHAR = "/";

    private static final String CURRENT_DIR_CHAR = ".";

    private static final String PARENT_DIR_CHAR = "..";

    private static FTPClient ftp = new FTPClient();

    private List<String> fileNameList = new ArrayList<>();

    public List<String> getFileNameList() {
        return fileNameList;
    }

    @PostConstruct
    public void init() {
        login("127.0.0.1", 21, "admin", "123456");
    }

    @PreDestroy
    public void destroy() {
        disConnection();
    }

    public FtpUtils() {
    }

    /**
     * 重载构造函数
     *
     * @param isPrintCommmand 是否打印与FTPServer的交互命令
     */
    public FtpUtils(boolean isPrintCommmand) {
        if (isPrintCommmand) {
            ftp.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
        }
    }

    /**
     * 登陆FTP服务器
     *
     * @param host     FTPServer IP地址
     * @param port     FTPServer 端口
     * @param username FTPServer 登陆用户名
     * @param password FTPServer 登陆密码
     * @return 是否登录成功
     * @throws IOException
     */
    public boolean login(String host, int port, String username, String password) {
        if (ftp.isAvailable()) {
            return true;
        }
        try {
            ftp.connect(host, port);
        } catch (IOException e) {
            LOGGER.error("can not connect ftp!", e);
        }
        if (FTPReply.isPositiveCompletion(ftp.getReplyCode())) {
            try {
                if (ftp.login(username, password)) {
                    ftp.enterLocalPassiveMode();
                    ftp.setControlEncoding("UTF-8");
                    ftp.setFileType(FTP.BINARY_FILE_TYPE);
                    return true;
                }
            } catch (IOException e) {
                LOGGER.error("can not login ftp!", e);
            }
        }
        return false;
    }

    /**
     * 清空集合
     */
    public void clearList() {
        fileNameList.clear();
    }

    /**
     * 关闭数据链接
     *
     * @throws IOException
     */
    public void disConnection() {
        try {
            if (ftp.isConnected()) {
                ftp.logout();
                ftp.disconnect();
                LOGGER.info("close ftp connection success!");
            }
        } catch (IOException e) {
            LOGGER.error("close ftp connection failed!", e);
        }
    }

    /**
     * 递归遍历目录下面指定的文件名
     *
     * @param pathName 需要遍历的目录，必须以"/"开始和结束
     * @param ext      文件的扩展名
     * @throws IOException
     */
    public void listFileName(String pathName, String ext) {
        if (pathName.startsWith(SEPARATOR_CHAR) && pathName.endsWith(SEPARATOR_CHAR)) {
            //更换目录到当前目录
            FTPFile[] files = new FTPFile[]{};
            try {
                ftp.changeWorkingDirectory(pathName);
                files = ftp.listFiles();
            } catch (IOException e) {
                LOGGER.info("traverse ftp dir failed!", e);
            }
            for (FTPFile file : files) {
                if (file.isFile()) {
                    if (file.getName().endsWith(ext)) {
                        fileNameList.add(pathName + file.getName());
                    }
                }
            }
        }
    }

    /**
     * 目录下面是否存在指定的文件
     */
    public int fileExist(String pathName) {
        int length = 0;
        //更换目录到当前目录
        try {
            ftp.changeWorkingDirectory(pathName);
            FTPFile[] ftpFiles = ftp.listFiles(pathName);
            length = ftpFiles.length;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return length;
    }

    /**
     * 遍历文件
     *
     * @param pathName 根路径
     */
    public void listFileName(String pathName) {
        listFileName(pathName, "zip");
    }


    /**
     * 获取图片流
     *
     * @param ftpPath 根路径
     */
    public byte[] downloadFtpFile(String ftpPath) {
        byte[] file = null;
        InputStream inputStream = null;
        try {
            inputStream = ftp.retrieveFileStream(ftpPath);
            file = IOUtils.toByteArray(inputStream);
        } catch (Exception e) {
            LOGGER.error("download ftp failed！", e);
        } finally {
            if (null != inputStream) {
                try {
                    inputStream.close();

                    if (ftp.completePendingCommand()) {
                        LOGGER.info("download fileName={} success!", ftpPath);
                    } else {
                        LOGGER.warn("download fileName={} failed!", ftpPath);
                    }
                } catch (IOException e) {
                    LOGGER.error("close ftp inputStream failed！", e);
                }
            }
        }
        return file;
    }

    /**
     * 删除ftp上的文件
     *
     * @param ftpFileName
     * @return true || false
     */
    public boolean removeFtpFile(String ftpFileName) {
        boolean flag = false;

        try {

            flag = ftp.deleteFile(ftpFileName);
            if (flag) {
                LOGGER.info("delete fileName={} success!", ftpFileName);
            } else {
                LOGGER.warn("delete fileName={} failed!", ftpFileName);
            }
        } catch (IOException e) {
            LOGGER.error("delete file failed!", e);
        }
        return flag;
    }

    public static void main(String[] args) {
        System.out.println(System.getProperty("user.dir"));
        return;

        /*
        FtpUtils ftpUtils = new FtpUtils();

        ftpUtils.login("34.8.8.206", 21, "admin", "admin");

        ftpUtils.listFileName("/D:/ftproot/2019gakm/");
        ftpUtils.listFileName("/D:/ftproot/2019yryp/");
        for (String arFile : ftpUtils.getFileNameList()) {
            System.out.println("filename=" + arFile);
            byte[] file = ftpUtils.downloadFtpFile(arFile);
            System.out.println("bytefile=" + file);
        }
        ftpUtils.disConnection();*/
    }
}