基于Java实现minio8下载文件并压缩zip

背景：多文件下载需要压缩zip并返回前端，文件夹层级结构保持不变

思路：先通过递归构建出所有的目录结构并生成zip，再服务器下载文件写入zip

实现：

1. 构建出每个文件的fullName，如果为顶层文件fullName即为当前文件名,如果有父级文件fullName为父级文件+ “/” + 子文件

示例： /opt/compose/docker-compose.yaml

	private void loadFullName(StorageVO storage) {
        if (storage.getParentId() == null) {
            storage.setFullName(storage.getName());
        } else {
            Optional<Storage> optional = this.repository.findById(storage.getParentId());
            if (optional.isPresent()) {
                StorageVO parent = StorageVO.of(optional.get());
                loadFullName(parent);
                storage.setFullName(parent.getFullName() + File.separator + storage.getName());
            } else {
                storage.setFullName(storage.getName());
            }
        }
    }

2. 前端传入需要下载的文件或文件夹id，查出所有的文件和文件夹，调用fullName方法,构建出zip需要的数据结构

public List<StorageVO> buildZip(List<String> ids) {

        BooleanBuilder predicate = new BooleanBuilder();
        predicate.and(QStorage.storage.deleted.eq(false));
        predicate.and(QStorage.storage.id.in(ids));
        List<StorageVO> storages = ListUtil.toList(this.repository.findAll(predicate))
                .stream()
                .map(storage -> StorageVO.of(storage).withChildren(storage.getChildren()))
                .toList();

        storages.addAll(storages.stream().map(StorageVO::getChildren).filter(Objects::nonNull).flatMap(Collection::stream).toList());
        storages.forEach(this::loadFullName);
        return storages;
    }

3.把步骤2构建好的数据结构写入到zip流，并根据是否为文件夹创建目录结构，在服务器下载文件写入到zip

public void downloadFileToServer(String tmpDir, List<StorageVO> treeParams, ZipArchiveOutputStream zipArchiveOutputStream) throws IOException {
        if (CollUtil.isNotEmpty(treeParams)) {
            for (StorageVO child : treeParams) {
                if (child.getIsDirectory()) {
                    tmpDir = tmpDir + File.separator + child.getFullName();
                    File mkdir = FileUtil.mkdir(tmpDir);
                    ZipArchiveEntry entry = new ZipArchiveEntry(mkdir, child.getFullName());
                    zipArchiveOutputStream.putArchiveEntry(entry);
                } else {
                    tmpDir = tmpDir + File.separator + child.getFullName();
                    File file = new File(tmpDir);
                    ZipArchiveEntry entry = new ZipArchiveEntry(file, child.getFullName());
                    zipArchiveOutputStream.putArchiveEntry(entry);

                    try (InputStream inputStream = minioHandle.download(child.getPath())) {
                        int i;
                        byte[] bytes = new byte[1024];
                        while ((i = inputStream.read(bytes)) != -1) {
                            zipArchiveOutputStream.write(bytes, 0, i);
                        }
                    }
                    zipArchiveOutputStream.closeArchiveEntry();
                    zipArchiveOutputStream.flush();
                }
            }
        }
    }

4. 下载文件，并把文件流写入response

public void downloadFiles(List<StorageVO> storages, HttpServletResponse response) {

        String tmpDir = System.getProperty("java.io.tmpdir") + "downloads";
        if (!new File(tmpDir).exists()) {
            FileUtil.mkdir(tmpDir);
        }
        ZipArchiveOutputStream zipArchiveOutputStream = null;
        try {
            String name = storages.size() > 1 ? storages.get(0).getName() + "等" + storages.stream()
                    .filter(storageVO -> !storageVO.getIsDirectory()).toList().size() + "个文件" : storages.get(0).getName();
            response.reset();
            response.setHeader("Accept-Ranges", "bytes");
            String fileName = URLEncoder.encode(name + ".zip", StandardCharsets.UTF_8).replaceAll("\\+", "%20");
            response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName);
            response.setHeader("Access-Control-Expose-Headers", "Content-Disposition");
            response.setContentType("application/json;charset=utf-8");

            zipArchiveOutputStream = new ZipArchiveOutputStream(response.getOutputStream());
            zipArchiveOutputStream.setUseZip64(Zip64Mode.AsNeeded);

            //在服务器上生成指定文件
            downloadFileToServer(tmpDir, storages, zipArchiveOutputStream);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            IoUtil.close(zipArchiveOutputStream);
            FileUtil.del(tmpDir);
        }
    }

5. controller代码.

    @RequestMapping("/{ids}/downloads")
    public Result<Object> downloads(@PathVariable("ids") String ids, HttpServletResponse response) {
        try {
            storageService.downloadFiles(storageService.buildZip(Arrays.stream(ids.split(",")).toList()), response);
        } catch (Exception e) {
            e.printStackTrace();
            throw new BizException("downloadFileError", "下载失败,请重试");
        }
        return Result.success();
    }