Comment implémenter des services de fichiers et de stockage via Spring Boot

@ResourceLoader
ResourceLoader resourceLoader;

File file = new File("D:/image.jpg"); //指定文件路径（绝对路径）
Resource resource = resourceLoader.getResource("file:" + file.getAbsolutePath()); //获取文件Resource对象
InputStream inputStream = resource.getInputStream(); //获取文件输入流

ClassPathResource classPathResource = new ClassPathResource("config.properties"); //获取配置文件Resource对象
InputStream inputStream = classPathResource.getInputStream(); //获取配置文件输入流

String url = "http://img.iplaysoft.com/wp-content/uploads/2019/free-images/free_stock_photo.jpg";
Resource resource = new UrlResource(url); //获取网络资源Resource对象
InputStream inputStream = resource.getInputStream(); //获取网络资源输入流

@PostMapping("/upload")
@ResponseBody
public String upload(@RequestParam("file") MultipartFile file) {
    //具体文件上传操作
    return "success";
}

@PostMapping("/upload")
@ResponseBody
public String upload(@RequestParam("file") MultipartFile file) {
    // 获取文件名
    String fileName = file.getOriginalFilename();
    // 设置保存路径
    String filePath = "D:/upload/";
    File dest = new File(filePath + fileName);
    try {
        file.transferTo(dest);
        // 具体业务操作
        return "success";
    } catch (IOException e) {
        e.printStackTrace();
        return "failure";
    }
}

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        multipartResolver.setMaxUploadSize(1000000);
        return multipartResolver;
    }
}

@GetMapping("/download")
public ResponseEntity<byte[]> download() throws IOException {
    String filePath = "D:/image.jpg";
    File file = new File(filePath);
    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Disposition", "attachment;filename=" + file.getName());
    headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
    byte[] bytes = FileUtils.readFileToByteArray(file);
    ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, headers, HttpStatus.OK);
    return responseEntity;
}

@GetMapping("/download_multi")
public ResponseEntity<byte[]> downloadMulti() throws IOException {
    String base = "D:/test/";
    File directoryToZip = new File(base);
    List<File> fileList = new ArrayList<>();
    getAllFiles(directoryToZip, fileList);
    byte[] zipBytes = getZipBytes(fileList, base);
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
    headers.add("Content-Disposition", "attachment; filename="files.zip"");
    headers.setContentLength(zipBytes.length);
    ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(zipBytes, headers, HttpStatus.OK);
    return responseEntity;
}

private byte[] getZipBytes(List<File> fileList, String basePath) throws IOException {
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    ZipOutputStream zipOutputStream = new ZipOutputStream(outputStream);
    for (File file : fileList) {
        String filePath = file.getAbsolutePath().substring(basePath.length());
        ZipEntry zipEntry = new ZipEntry(filePath);
        zipOutputStream.putNextEntry(zipEntry);
        FileInputStream inputStream = new FileInputStream(file);
        IOUtils.copy(inputStream, zipOutputStream);
        inputStream.close();
        zipOutputStream.closeEntry();
    }
    zipOutputStream.close();
    byte[] bytes = outputStream.toByteArray();
    outputStream.close();
    return bytes;
}

private void getAllFiles(File dir, List<File> fileList) {
    File[] files = dir.listFiles();
    for (File file : files) {
        if (file.isDirectory()) {
            getAllFiles(file, fileList);
        } else {
            fileList.add(file);
        }
    }
}

String fileRoot = "/data/files/";
Path rootPath = Paths.get(fileRoot).normalize().toAbsolutePath();
if (!Files.exists(rootPath)) {
    Files.createDirectories(rootPath);
}

@Service
public class FileStorageService {

    private Path fileStorageLocation;

    @Autowired
    public FileStorageService(@Value("${file.upload-dir}") String fileRoot) {
        this.fileStorageLocation = Paths.get(fileRoot).normalize().toAbsolutePath();
        try {
            Files.createDirectories(this.fileStorageLocation);
        } catch (Exception e) {
            throw new FileStorageException("Could not create the directory where the uploaded files will be stored.", e);
        }
    }

    public String storeFile(MultipartFile file) {
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        try {
            if (fileName.contains("..")) {
                throw new FileStorageException("Sorry! Filename contains invalid path sequence " + fileName);
            }
            Path targetLocation = this.fileStorageLocation.resolve(fileName);
            Files.copy(file.getInputStream(), targetLocation, StandardCopyOption.REPLACE_EXISTING);
            return fileName;
        } catch (IOException ex) {
            throw new FileStorageException("Could not store file " + fileName + ". Please try again!", ex);
        }
    }

    public Resource loadFileAsResource(String fileName) {
        try {
            Path filePath = this.fileStorageLocation.resolve(fileName).normalize();
            Resource resource = new UrlResource(filePath.toUri());
            if (resource.exists()) {
                return resource;
            } else {
                throw new MyFileNotFoundException("File not found " + fileName);
            }
        } catch (MalformedURLException ex) {
            throw new MyFileNotFoundException("File not found " + fileName, ex);
        }
    }
}