Java怎么实现FTP的上传与下载功能

这篇文章主要讲解了"Java怎么实现FTP的上传与下载功能"，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习"Java怎么实现FTP的上传与下载功能"吧！

JAVA操作FTP服务器，只需要创建一个FTPClient即可，所有的操作都封装在FTPClient中，JDK自带的有FTPClient（sun.net.ftp.FtpClient），也可以用第三方的FTPClient，一般使用apache的FTPClient（org.apache.commons.net.ftp.FTPClient），本文将使用apache的FTPClient，API都大同小异

关键依赖：commons-net

对常用操作（上传、下载）封装成工具类

package com.day0322;import org.apache.commons.io.IOUtils;import org.apache.commons.lang3.StringUtils;import org.apache.commons.net.ftp.FTPClient;import org.apache.commons.net.ftp.FTPReply;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;/** * FTP工具类 * 文件上传 * 文件下载 */public class FTPUtil {    private static final Logger log = LoggerFactory.getLogger(FTPUtil.class);    /**     * 设置缓冲区大小4M     **/    private static final int BUFFER_SIZE = 1024 * 1024 * 4;    /**     * 本地字符编码     **/    private static String LOCAL_CHARSET = "GBK";    /**     * UTF-8字符编码     **/    private static final String CHARSET_UTF8 = "UTF-8";    /**     * OPTS UTF8字符串常量     **/    private static final String OPTS_UTF8 = "OPTS UTF8";    /**     * FTP协议里面，规定文件名编码为iso-8859-1     **/    private static final String SERVER_CHARSET = "ISO-8859-1";    private static FTPClient ftpClient = null;    /**     * 连接FTP服务器     */    private static void login(OaFtp oaFtp) {        ftpClient = new FTPClient();        try {            ftpClient.connect(oaFtp.getIp(), Integer.valueOf(oaFtp.getPort()));            ftpClient.login(oaFtp.getName(), oaFtp.getPwd());            ftpClient.setBufferSize(BUFFER_SIZE);            ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);            int reply = ftpClient.getReplyCode();            if (!FTPReply.isPositiveCompletion(reply)) {                closeConnect();            }        } catch (Exception e) {            log.error("",e);            throw new RuntimeException(e);        }    }    /**     * 关闭FTP连接     */    private static void closeConnect() {        if (ftpClient != null && ftpClient.isConnected()) {            try {                ftpClient.logout();                ftpClient.disconnect();            } catch (IOException e) {                log.error("",e);            }        }    }    /**     * FTP服务器路径编码转换     *     * @param ftpPath FTP服务器路径     * @return String     */    private static String changeEncoding(String ftpPath) {        String directory = null;        try {            if (FTPReply.isPositiveCompletion(ftpClient.sendCommand(OPTS_UTF8, "ON"))) {                LOCAL_CHARSET = CHARSET_UTF8;            }            directory = new String(ftpPath.getBytes(LOCAL_CHARSET), SERVER_CHARSET);        } catch (Exception e) {            log.error("",e);        }        return directory;    }    /**     * 改变工作目录     * 如果没有，则创建工作目录     * @param path     */    private static void changeAndMakeWorkingDir(String path) {        try {            ftpClient.changeWorkingDirectory("/");            path = path.replaceAll("\\\\","/");            String[] path_array = path.split("/");            for (String s : path_array) {                boolean b = ftpClient.changeWorkingDirectory(s);                if (!b) {                    ftpClient.makeDirectory(s);                    ftpClient.changeWorkingDirectory(s);                }            }        } catch (IOException e) {            log.error("",e);            throw new RuntimeException(e);        }    }    /**     * 上传     * @param oaFtp     * @param filename     * @param dirPath     * @param in     * @return     */    public static boolean upload (OaFtp oaFtp, String filename, String dirPath, InputStream in) {        login(oaFtp);        if (!ftpClient.isConnected()) {            return false;        }        boolean isSuccess = false;        if (ftpClient != null) {            try {                if (FTPReply.isPositiveCompletion(ftpClient.sendCommand(OPTS_UTF8, "ON"))) {                    LOCAL_CHARSET = CHARSET_UTF8;                }                ftpClient.setControlEncoding(LOCAL_CHARSET);                String path = changeEncoding(dirPath);                changeAndMakeWorkingDir(path);                isSuccess = ftpClient.storeFile(new String(filename.getBytes(), SERVER_CHARSET), in);            } catch (Exception e) {                log.error("",e);            } finally {                closeConnect();            }        }        return isSuccess;    }    /**     * 下载     * @param oaFtp     * @param filename     * @param dirPath     * @param out     * @return     */    public static void download (OaFtp oaFtp, String filename, String dirPath, FileOutputStream out) {        // 登录        login(oaFtp);        if (ftpClient != null) {            try {                String path = changeEncoding(dirPath);                changeAndMakeWorkingDir(path);                String[] fileNames = ftpClient.listNames();                if (fileNames == null || fileNames.length == 0) {                    return;                }                for (String fileName : fileNames) {                    String ftpName = new String(fileName.getBytes(SERVER_CHARSET), LOCAL_CHARSET);                    if (StringUtils.equals(ftpName,filename)) {                        InputStream in = ftpClient.retrieveFileStream(fileName);                        IOUtils.copy(in,out);                    }                }            } catch (IOException e) {                log.error("",e);            } finally {                closeConnect();            }        }    }}

测试

1.上传

2.下载

感谢各位的阅读，以上就是"Java怎么实现FTP的上传与下载功能"的内容了，经过本文的学习后，相信大家对Java怎么实现FTP的上传与下载功能这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是，小编将为大家推送更多相关知识点的文章，欢迎关注！