pom依赖：

<dependency>

    <groupId>commons-net</groupId>

    <artifactId>commons-net</artifactId>

    <version>3.6</version>

</dependency>

java代码：

package com.cong.quartz.util;

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;
import java.io.IOException;
import java.io.InputStream;

/**
 * ftp读取文件
 */
public class FtpUtils {

    public static final String ip = "49.232.136.**";
    public static final int port = 21;
    public static final String username = "****";
    public static final String password = "****";

    public  boolean readFtp() {
        FTPClient ftp = new FTPClient();
        InputStream ins = null;
        try {
            int reply;
            ftp.connect(ip,port);
            ftp.login(username,password);
            reply = ftp.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply)) {
                ftp.disconnect();
                return false;
            }
            ftp.changeWorkingDirectory("/home/fireuser/soil");//转移到FTP服务器目录
            FTPFile[] fs = ftp.listFiles();
            for (FTPFile ff:fs){
                //从服务器读取指定的文件
                ins = ftp.retrieveFileStream(ff.getName());

                //根据InputStream操作文件的相关代码写在这里

                //主动调用一次getreply,解决再次读取返回null的问题
                ftp.getReply();
            }

            ftp.logout();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if (ins != null){
                    ins.close();
                }
                if(ftp.isConnected()){
                    ftp.disconnect();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return true;
    }
}