将图片存储在H2数据库spring boot thymleaf中

Question

美好的一天.我想将图像存储在h2数据库中,然后在html页面中检索并显示相同的图像.我使用的是spring boot和文件上传方法,但是我在绑定结果中遇到错误

这是页面/类:

Category.java

package com.vishal.project.entities;

@Entity
@Table(name="category")
public class Category implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy= GenerationType.IDENTITY)
@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;
}

public void setBooks(Set<Book> books) {
    Books = books;
}

public Long getId() {
    return id;
}
public void setCategoryID(Long id) {
    this.id = id;
}
public String getCategoryName() {
    return CategoryName;
}
public void setCategoryName(String categoryName) {
    CategoryName = categoryName;
}

@Override
public String toString() {

    return "Category ID:" + id + 
           "Category Name:"+ CategoryName;
}


}

Categorycontroller.java

package com.vishal.project.web;


import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;
import com.vishal.project.entities.Category;
import com.vishal.project.services.CategoryService;
import com.vishal.project.util.Message;


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


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

@Autowired
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}" , consumes="Multipart/formdata")
public String show(@PathVariable Long id, Model model) {
    Category category = categoryService.findbyID(id);


    model.addAttribute("category", category);
    return "showCategory";
}

@GetMapping(value = "/edit/{id}")
public String updateForm(@PathVariable Long id, Model model) {
    model.addAttribute("category", categoryService.findbyID(id));
    return "updateCategory";
}

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

    uiModel.addAttribute("category", category);
    return "updateCategory";
}


@PostMapping(value = "/upload")
public String saveCategory(@Valid @ModelAttribute("category") Category category, BindingResult bindingResult,
        Model uiModel, HttpServletRequest httpServletRequest, RedirectAttributes redirectAttributes,
        Locale locale, @RequestParam(value="file", required=true) MultipartFile file) {
    logger.info("Creating Category....");
    logger.info("Category ID" + category.getId());
    logger.info("Category ID" + category.getCategoryName());
    logger.info("Category ID" + category.getCategoryPhoto());
    if(bindingResult.hasErrors())
    {
        logger.info("Error:", bindingResult.getAllErrors());
        logger.debug("field Error:", bindingResult.getFieldError());
        uiModel.addAttribute("message", new Message("error", messageSource.getMessage("category_save_fail", new Object[] {}, locale)));
        uiModel.addAttribute("category", category);
        return "updateCategory";
    }
    uiModel.asMap().clear();
    redirectAttributes.addFlashAttribute("message", 
            new Message("success", messageSource.getMessage("Category_save_success", new Object[] {}, locale)));
    //process upload file 
    logger.info("File Name :", file.getName() );
    logger.info("File Size :", file.getSize() );
    logger.info("File content type :", file.getContentType() );
    if(file != null) {
    byte[] filecontent = null;
    try
    {
        InputStream inputStream = file.getInputStream();
        if(inputStream == null) 
            logger.debug("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().toString();
}

}

categoryShow.page

<body>
<div th:replace="fragments/header_admin :: header_admin">Header</div>
<div class="container">

<h1>Category Details</h1>

<div>
    <form class="form-horizontal" th:object="${category}" >
    <input type="hidden" th:field="*{id}"/>
        <div class="form-group">
            <label class="col-sm-2 control-label">Category Name:</label>
            <div class="col-sm-10">
                <p class="form-control-static" th:text="${CategoryName}"> 
</p></div>
        </div>

        <div class="form-group">
            <label class="col-sm-2 control-label" >Category Photo</label>
            <div class="col-sm-10">
                <p class="form-control-static" ><img alt="CatName" 
  th:src="@{CategoryPhoto}" /> </p></div>
        </div>
    </form>
</div>

categoryUpdate页面(创建或更新包含详细信息和图像的类别)

<div class="container">

<h1>Category Details</h1>

<div>
    <form  class="form-horizontal" th:object="${category}" th:action="@{/categories/upload}" 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" class="form-control" th:field="*{CategoryPhoto}"/>
            </div>
        </div>
        <div class="row">
            <button class="btn btn-default">Save</button>
        </div>
    </form>
</div>
<div th:insert="~{fragments/footer :: footer}">&copy; 2017 Iuliana Cosmina & Apress</div>

错误:我在CategoryController.saveCategory()方法的bindingResult中获取.

当我调试代码时,我收到错误.这是一张图片来展示:

我很难使用thymleaf在CategoryShow页面上显示图像.任何帮助,将不胜感激.

更新:任何人都可以告诉我这个错误意味着什么,请:

Failed to convert property value of    type 'org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile' to required type 'byte[]' for property 'CategoryPhoto'; nested exception is 
java.lang.IllegalArgumentException: Cannot convert value of type 'org.springframework.web.multipart.support.
StandardMultipartHttpServletRequest$StandardMultipartFile' to required type 'byte' for property
'CategoryPhoto[0]': PropertyEditor [org.springframework.beans.propertyeditors.CustomNumberEditor] returned 
inappropriate value of type 'org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile' 

**最终更新:我收到此错误:**所需的请求部分'文件'不存在

Answer 1

您始终可以做的就是将工作文件上传示例与您的进行比较。

另一件有助于将输入名称与控制器方法期望文件的名称进行比较的事情。

如果您发布的代码仍然相关，您可以在模板中的文件输入中找到名称“Fileimport”，但在您的控制器中您需要文件（ @RequestParam(value="file", required=false) ）。

其他有助于您调试的事情：

• 使用浏览器的开发人员工具并查看您通过网络发送的内容
• 在服务器端记录传入的请求（以这种方式，或者对您来说太复杂，您可以简单地迭代参数名称并记录它们（如果可能的话，也记录它们的值）

如果这对您没有帮助，那么请更新帖子：更新您的代码（模板+控制器，如果更改）并使用更好的堆栈跟踪：更好我的意思是您不仅应该显示堆栈跟踪的最后 N 行，而且应该显示至少到执行代码的第一行（换句话说，类名以包开头），如果第一个 Caused by 或第二个（如果有意义的话）存在，那就更好了。