从数据库H2错误spring boot thymeleaf上传和显示图像

Posted 2023-02-26

【中文标题】从数据库H2错误spring boot thymeleaf上传和显示图像

【英文标题】：Image uploading and displaying from database H2 error spring boot thymleaf

【发布时间】：2019-01-31 21:53:35

【问题描述】：

我正在尝试使用 Springboot、thymleaf、H2 嵌入式构建一个书店网站。当我尝试上传新书类别的图片时，它给了我一个空指针错误

这是我的 Category.class

@Entity
@Table(name="category")
public class Category implements Serializable 

/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy= GenerationType.AUTO)
@Column(name="ID")
private Long id;

@Size(min=1, max=90)
@Column(name="CATEGORY_NAME")
private String CategoryName;


@Lob
@Column(name="CATEGORY_PHOTO")
private byte[] CategoryPhoto;


public Category(Long id, @Size(min = 1, max = 90) String categoryName, byte[] categoryPhoto) 
    super();
    this.id = id;
    CategoryName = categoryName;
    CategoryPhoto = categoryPhoto;


public byte[] getCategoryPhoto() 
    return CategoryPhoto;


public void setCategoryPhoto(byte[] categoryPhoto) 
    CategoryPhoto = categoryPhoto;


public Category() 

@OneToMany(mappedBy = "category", cascade=CascadeType.ALL, orphanRemoval=true)
private Set<Book> Books = new HashSet<>();

public Set<Book> getBooks() 
    return Books;

类别控制器：

@Controller
@RequestMapping(value="/categories")
public class CategoryController 

private final Logger logger = LoggerFactory.getLogger(BookController.class);

private MessageSource  messageSource;

@Autowired 
private CategoryService categoryService;

@GetMapping
public String list(Model uiModel) 
    logger.info("Listing categories:");
    List<Category> categories = categoryService.findALL();
    uiModel.addAttribute("categories", categories);
    logger.info("No. of categories: " + categories.size());
    return "categories";


@GetMapping(value = "/id")
public String show(@PathVariable Long id, Model model) 
    Category category = categoryService.findbyID(id);
    
    if(category.getCategoryPhoto() == null) 
        logger.debug("Downloading photo for id:  with size",
          category.getId(), category.getCategoryPhoto().length);
    
    model.addAttribute("category", category);
    return "showCategory";


@GetMapping(value = "/new")
public String create(Model uiModel) 
    logger.info("creating Category ...");
    Category category = new Category();
    uiModel.addAttribute("category", category);
    return "updateCategory";


@PostMapping
public String saveCategory(@Valid Category category, BindingResult bindingResult,
        Model uiModel, HttpServletRequest httpServletRequest, RedirectAttributes redirectAttributes,
        Locale locale, @RequestParam(value="file", required=false) Part file) 
    logger.info("Creating Category....");
    if(bindingResult.hasErrors())
    
        uiModel.addAttribute("message", new Message("error", messageSource.getMessage("category_save_fail", new Object[] , locale)));
        uiModel.addAttribute("Category", category);
        return "categories/new";
    
    uiModel.asMap().clear();
    redirectAttributes.addFlashAttribute("message", new Message("success", messageSource.getMessage("Category_save_success", new Object[] , locale)));
    logger.info("Category ID" + category.getId());
    //process upload file 
    if(file != null) 
    logger.info("File name:" + file.getName());
    logger.info("File size:" + file.getSize());
    logger.info("File content type:" + file.getContentType());
    byte[] filecontent = null;
    try
    
        InputStream inputStream = file.getInputStream();
        if(inputStream == null)
            logger.info("File InputStream is null");
        filecontent = IOUtils.toByteArray(inputStream);
        category.setCategoryPhoto(filecontent);
    catch(IOException ex) 
        logger.error("Error Saving uploaded file");
    
    category.setCategoryPhoto(filecontent);
    
    categoryService.save(category);
    return "redirect:/categories/" + category.getId();

updatecategories.html 页面 :: 用于创建新类别并使用 Name 和 Categoryphoto 更新类别

<form class="form-horizontal" th:object="$category" th:action="@/categories" method="post" enctype="multipart/form-data">
        <input type="hidden" th:field="*id"/>
        <div class="form-group">
            <label class="col-sm-2 control-label">Category Name</label>
            <div class="col-sm-10">
                <input class="form-control" th:field="*CategoryName"/>
            </div>
        </div>
          <div class="form-group">
            <label class="col-sm-2 control-label">Category Photo</label>
            <div class="col-sm-10">
                <input name="file" type="file" value="upload" class="form-control" th:field="*CategoryPhoto"/>
            </div>
        </div>
        <div class="row">
            <button class="btn btn-default">Save</button>
        </div>
    </form>

show Categories.html页面，用于在创建或更新后显示类别名称和照片

<form class="form-horizontal" th:object="$category" th:action="@/categories" method="post" enctype="multipart/form-data">
        <input type="hidden" th:field="*id"/>
        <div class="form-group">
            <label class="col-sm-2 control-label">Category Name</label>
            <div class="col-sm-10">
                <input class="form-control" th:field="*CategoryName"/>
            </div>
        </div>
          <div class="form-group">
            <label class="col-sm-2 control-label">Category Photo</label>
            <div class="col-sm-10">
                <input name="file" type="file" value="upload" class="form-control" th:field="*CategoryPhoto"/>
            </div>
        </div>
        <div class="row">
            <button class="btn btn-default">Save</button>
        </div>
    </form>

这是我创建新类别时的图像

错误图片：

抱歉，问题描述很长，但我想澄清一下细节。帮助将不胜感激。

【问题讨论】：

请有人帮我解决这个问题？

【参考方案1】：

我得到了一个错误，我使用 MessageSource 而没有自动装配它完成了。并将消息添加到我的属性文件中。