如何使用spring boot从数据库中存储和检索图像文件

Question

我正在构建一个有角度的 springboot 应用程序，但我找到了很多方法来做到这一点，其中一些我真的不明白。 如何一次存储 1 个或多个图像并检索它们。

Answer 1

您可以使用@Lob 在数据库中存储图像或任何文件。下面的例子展示了这种方法的简单实现

@Entity
@Table(name = "file")
public class File {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "uuid")
    private String uuid;

    @Column(name = "content_type")
    private String contentType;

    @Column(name = "extension")
    private String extension;

    @Lob
    @Column(name = "content", columnDefinition = "LONGBLOB")
    private byte[] content;
}



@Service
public class FileService {
private final FileRepository repository;

@Autowired
public FileService(FileRepository repository) {
    this.repository = repository;
}

@Transactional
public StreamingResponseBody download(Long id, HttpServletResponse response) {
    final File file = repository.findById(id).orElseThrow(NotFoundException::new);
    return outputStream -> {
        String fileName = (file.getUuid() + file.getExtension()).trim();
        response.setContentType(file.getContentType());
        response.setHeader("Content-Disposition", "attachment; filename=" + fileName);

        outputStream.write(file.getContent());
        outputStream.flush();
    };
}

public FileDto create(MultipartFile multipartFile, boolean general) {
    String fileName = multipartFile.getOriginalFilename();
    String fileExtension = Objects.requireNonNull(fileName).substring(fileName.lastIndexOf('.'));
    String uuid = UUID.randomUUID().toString();
    UserDto user = contextUtils.getPrincipal();

    File file = new File();
    file.setUuid(uuid);
    file.setContentType(multipartFile.getContentType());
    file.setExtension(fileExtension);
    file.setGeneral(general);
    file.setContent(multipartFile.getBytes());
    file.setId(repository.save(file).getId());

    return file;
}

}