java web ftp 打包下載檔案

import org.apache.commons.io.FileUtils;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.
 
util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

 /**
     * 多檔案下載
     * @param fileSns  檔案sn
     * @param fileName 檔名稱sn
     * @param response 響應
     * @return 檢視
     */
 

    @RequestMapping(value = "/download-files", method = RequestMethod.GET)
    public void downloadFiles(@RequestParam List<Long> fileSns, String fileName, HttpServletResponse response) {
        if (fileSns == null || fileSns.isEmpty()) {
            throw new RuntimeException("檔案為空");
        }
 

        //獲取ftp儲存的檔案資訊
        List<File> files = fileService.findListBySn(fileSns);
        if (files.isEmpty()) {
            throw new RuntimeException("沒有找到檔案");
        }
        //臨時檔案
        java.io.File tempFile;
        //Zip工具
        ZipOutputStream out = null;
        //獲取臨時檔案目錄
        java.io.File fileDirecotry = FileUtils.getTempDirectory();
        if (StringUtils.isNotBlank(fileName)) {
            fileName += "-" + System.currentTimeMillis();
        } else {
            fileName = UUID.randomUUID().toString();
        }
        try {
            //建立臨時zip檔案
            tempFile = java.io.File.createTempFile(fileName, ".zip", fileDirecotry);
            out = new ZipOutputStream(new FileOutputStream(tempFile));
            List<String> names = new ArrayList<>();
            //將多個檔案寫入zip
            for (File file : files) {
                //檔名去重
                String name = distinctName(names, file.getOriginal());
                //往zip檔案流中寫檔案
                out.putNextEntry(new ZipEntry(name));
                //省去ftp連結
                ftpClient.retrieveFile(file.getPath(), out)
                out.flush();
                out.closeEntry();
            }
            //所有檔案寫完後一定要關閉輸出流，否則檔案下載會不完整。
            out.flush();
            out.close();

            //將zip檔案寫入響應
            response.setContentType("APPLICATION/OCTET-STREAM");
            response.setHeader("Content-Disposition", "attachment; filename=" + new String(tempFile.getName().getBytes("UTF-8"), "ISO-8859-1"));
            OutputStream os = new BufferedOutputStream(response.getOutputStream());
            InputStream in = new BufferedInputStream(new FileInputStream(tempFile));
            int len;
            byte[] buf = new byte[1024];
            while ((len = in.read(buf)) > 0) {
                os.write(buf, 0, len);
            }
            os.flush();
            os.close();
            in.close();
            response.flushBuffer();
            FileUtils.deleteQuietly(tempFile);
        } catch (Exception e) {
            e.printStackTrace();
            if (out != null) {
                try {
                    out.close();
                } catch (IOException ie) {
                    ie.printStackTrace();
                }
            }
            throw new RuntimeException();
        }
    }
    /**
     * 檔名去重
     * @param names 名稱集合
     * @param name  檔名
     * @return 去重檔名
     */
    private String distinctName(List<String> names, String name) {
        if (!names.contains(name)) {
            names.add(name);
            return name;
        }
        int count = 0;
        int pos = name.lastIndexOf(StringUtils.DOT);
        String namePrev = name;
        String nameEnd = "";
        if (pos > 0) {
            namePrev = name.substring(0, pos);
            nameEnd = name.substring(pos);
        }
        String tmpName;
        do {
            count++;
            tmpName = namePrev + StringUtils.LEFT_BRACKET + count + StringUtils.RIGHT_BRACKET + nameEnd;
        } while (names.contains(tmpName));
        names.add(tmpName);
        return tmpName;
    }