这篇文章主要讲解了“FTP服务器打包下载文件的步骤”，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“FTP服务器打包下载文件的步骤”吧！
需求：从ftp服务器打包下载文件
解决步骤：1.从ftp服务器把各个文件下载到本地服务器(一般是安装tomcat的服务器，项目自己电脑跑的本地服务器就是自己电脑)指定目录中
2.在本地服务器打包下载好的文件夹打包，返回打包好的File zip
3.zip文件用流写入reponse，达到用户下载效果
准备文件：
// 封装所有需要打包下载的文件地址请求类
public class DownloadPackageReq implements Serializable {// 本地服务器临时存放目录名(尽量唯一.eg:"menutree20200904112125") private String localTempDirName; // 打包下载本地服务器文件夹名字private List<DownloadPackageListReq> downloadPackageListReqList; // 需要下载所有文件路径和名称
}// FTPClientUtils：ftp工具类
public static FTPClientUtils init() { FTPClientUtils ftp = new FTPClientUtils(); ftp.setHost(host); ftp.setPort(port); ftp.setUsername(username); ftp.setPassword(password); ftp.setBinaryTransfer(true); ftp.setPassiveMode(false); ftp.setEncoding("utf-8"); return ftp;
}/** * 下载一个远程文件到本地的指定文件 *
* @param remoteAbsoluteFile * 远程文件名(包括完整路径,eg:/MTL/test/menutree_attachment/file.xlsx) * @param localAbsoluteFile * 本地文件名(包括完整路径) * @param autoClose * 是否自动关闭当前连接 *
* @return 成功时，返回true，失败返回false * @throws Exception */public boolean get(String remoteAbsoluteFile, String localAbsoluteFile, boolean autoClose) throws Exception { OutputStream output = null; try {
output = new FileOutputStream(localAbsoluteFile); return get(remoteAbsoluteFile, output, autoClose);
} catch (FileNotFoundException e) { throw new Exception("local file not found.", e);
} finally { try { if (output != null) {
output.close();
}
} catch (IOException e) { throw new Exception("Couldn't close FileOutputStream.", e);
}
}
}/** * 下载一个远程文件到指定的流 处理完后记得关闭流 *
* @param remoteAbsoluteFile * @param output * @param autoClose * @return * @throws Exception */public boolean get(String remoteAbsoluteFile, OutputStream output, boolean autoClose) throws Exception { try { FTPClient ftpClient = getFTPClient(); // 处理传输 return ftpClient.retrieveFile(remoteAbsoluteFile, output);
} catch (IOException e) { throw new Exception("Couldn't get file from server.", e);
} finally { if (autoClose) {
disconnect(); // 关闭链接 }
}
}第一步：
public File downloadMenuTreeAttachment(Integer menutreeId) throws Exception {
// 从数据库拿到menutreeId对应的所有文件地址List<ResourcesMenutreeListVo> resourcesMenutreeLists = resourcesMenutreeListMapper.selExistingAttachment(menutreeId);DownloadPackageReq req = new DownloadPackageReq();if (CollectionUtils.isNotEmpty(resourcesMenutreeLists)) {req.setLocalTempDirName(resourcesMenutreeLists.get(0).getMenutreeName() + DateUtils.dateTimeNow());List<DownloadPackageListReq> dpList = new ArrayList<>();for(ResourcesMenutreeListVo temp : resourcesMenutreeLists) {DownloadPackageListReq dpReq = new DownloadPackageListReq();
// 文件名称，用来下载ftp服务器文件修改文件名(因为ftp文件都是uuid名称)String fileName = temp.getModuleName() + "_" + temp.getEngineerName();dpReq.setFileName(fileName);dpReq.setFileFtpUrl(temp.getMenutreeAttachment());dpList.add(dpReq);
}req.setDownloadPackageListReqList(dpList);
} else {req.setLocalTempDirName("空菜单树" + DateUtils.dateTimeNow());
}return ftpService.zipFiles(req);
}public File zipFiles(DownloadPackageReq req) throws Exception {HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();// 本地服务器暂存路径 String localTempDir = request.getSession().getServletContext().getRealPath("/") + req.getLocalTempDirName() + File.separator;logger.info("本地服务器暂存路径:" + localTempDir);File dir = new File(localTempDir);if ( ! dir.exists()) {dir.mkdir();
}if (CollectionUtils.isNotEmpty(req.getDownloadPackageListReqList())) {List<DownloadPackageListReq> downloadList = req.getDownloadPackageListReqList();FTPClientUtils ftp = FTPClientUtils.init();for(int i=0; i<downloadList.size(); i++) {// 是否关闭传输流(最后一份文件传输完毕关闭) boolean isCloseStream = false;if (i == downloadList.size() - 1) {
isCloseStream = true;
}DownloadPackageListReq temp = downloadList.get(i);String fileFtpUrl = temp.getFileFtpUrl();String suffix = "";if (fileFtpUrl.contains(".") && !fileFtpUrl.endsWith(".")) {// 文件后缀名 suffix = fileFtpUrl.substring(fileFtpUrl.lastIndexOf("."));
}// 本地服务器存放完整路径(包含文件名) String localUrl = localTempDir + temp.getFileName() + suffix;// 下载的第一个参数远程路径如果是FTP服务器，就采用服务器完整文件路径(eg:/MTL/test/menutree_attachment/file.xlsx),因为初始化ftp服务器就带了ip端口 boolean result = ftp.get(temp.getFileFtpUrl(), localUrl, isCloseStream);
}
}
// 打包下载好的文件File zipFile = ZipUtil.zip(localTempDir, localTempDir + req.getLocalTempDirName() + ".zip");return zipFile;
}第二步：
public class ZipUtil {private static Logger logger = Logger.getLogger(ZipUtil.class);/** * 缓冲器大小 */ private static final int BUFFER = 512;/** * 压缩方法 （可以压缩空的子目录） * * @param srcPath 压缩源路径 * @param zipFileName 目标压缩文件 * @return */ public static File zip(String srcPath, String zipFileName) {ZipOutputStream zipOutputStream = null;InputStream inputStream = null;File outputZipFile = null;try {// 检查文件是否存在，是的话先删除 outputZipFile = new File(zipFileName);if (outputZipFile.exists()) {
outputZipFile.delete();
}File srcFile = new File(srcPath);List<File> fileList = FileUtil.getAllFiles(srcFile);// 所有要压缩的文件 byte[] buffer = new byte[BUFFER];// 缓冲器 ZipEntry zipEntry = null;int readLength = 0;// 每次读出来的长度 zipOutputStream = new ZipOutputStream(new FileOutputStream(zipFileName));for (File file : fileList) {if (file.isFile()) {// 若是文件，则压缩这个文件 zipEntry = new ZipEntry(getRelativePath(srcPath, file));
zipEntry.setSize(file.length());
zipEntry.setTime(file.lastModified());
zipOutputStream.putNextEntry(zipEntry);
inputStream = new BufferedInputStream(new FileInputStream(file));while ((readLength = inputStream.read(buffer, 0, BUFFER)) != -1) {
zipOutputStream.write(buffer, 0, readLength);
}
} else {// 若是目录（即空目录）则将这个目录写入zip条目 zipEntry = new ZipEntry(getRelativePath(srcPath, file) + File.separator);
zipOutputStream.putNextEntry(zipEntry);
}
} // end for } catch (FileNotFoundException e) {logger.error("zip fail!", e);
} catch (IOException e) {logger.error("zip fail!", e);
} finally {close(inputStream);close(zipOutputStream);
}// 返回文件输出流 outputZipFile = new File(zipFileName);return outputZipFile;
}/** * 关闭流 */ private static void close(Closeable c) {if (c == null)return;try {
c.close();
} catch (IOException e) {logger.error("close fail!", e);
}
c = null;
}/** * 取相对路径 依据文件名和压缩源路径得到文件在压缩源路径下的相对路径 * * @param dirPath 压缩源路径 * @param file * @return 相对路径 */ public static String getRelativePath(String dirPath, File file) {File dir = new File(dirPath);String relativePath = file.getName();while (true) {
file = file.getParentFile();if (file == null) {break;
}if (file.equals(dir)) {break;
} else {
relativePath = file.getName() + "/" + relativePath;
}
} // end while return relativePath;
}
}第三步：Controller控制器，Result是自己封装的返回类，可以自定义String之类的返回
public Result downloadMenuTreeAttachment(Integer menutreeId, HttpServletResponse response) {BufferedInputStream bis = null;OutputStream os = null;try {File file = resourcesMenutreeListService.downloadMenuTreeAttachment(menutreeId);
response.reset();
response.setCharacterEncoding("utf-8");
response.setContentLength((int) file.length());// 设置content-disposition响应头控制浏览器以下载的形式打开文件，中文文件名要使用URLEncoder.encode方法进行编码，否则会出现文件名乱码 response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(file.getName(), "UTF-8"));
bis = new BufferedInputStream(new FileInputStream(file));
os = response.getOutputStream();byte[] buff = new byte[1024];int i = 0;while ((i = bis.read(buff)) != -1) {
os.write(buff, 0, i);
os.flush();
}
} catch (Exception e) {log.error("{}",e);return ResultGenerator.genFailResult("下载失败");
} finally {try {
bis.close();
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}return ResultGenerator.genSuccessResult();
}感谢各位的阅读，以上就是“FTP服务器打包下载文件的步骤”的内容了，经过本文的学习后，相信大家对FTP服务器打包下载文件的步骤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。这里是亿速云，小编将为大家推送更多相关知识点的文章，欢迎关注！
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