帮我用idea写一个javaweb代码，要求利用JSP Web或SSH、SSM、SpringBoot等框架，实现添加书籍的分类管理、添加图书、查询书籍、预览、附件上传功能

好的，我可以给您提供一个Spring Boot框架下的示例代码，包含了添加书籍的分类管理、添加图书、查询书籍、预览和附件上传功能。请注意，这只是一个示例代码，您需要根据实际需求进行修改和完善。

1. 创建Maven工程，添加Spring Boot和Web依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <!-- 文件上传依赖 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.4</version>
    </dependency>
</dependencies>

2. 编写Controller代码

@Controller
@RequestMapping("/book")
public class BookController {
    @Autowired
    private BookService bookService;
    
    // 添加书籍分类
    @PostMapping("/addCategory")
    public String addCategory(@RequestParam("name") String name) {
        bookService.addCategory(name);
        return "redirect:/book/category";
    }
    
    // 查询书籍分类
    @GetMapping("/category")
    public String category(Model model) {
        List<Category> categories = bookService.getCategories();
        model.addAttribute("categories", categories);
        return "category";
    }
    
    // 添加图书
    @PostMapping("/addBook")
    public String addBook(@ModelAttribute Book book, @RequestParam("file") MultipartFile file) {
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        book.setCover(fileName);
        bookService.addBook(book);
        String uploadDir = "book-covers/" + book.getId();
        FileUploadUtil.saveFile(uploadDir, fileName, file);
        return "redirect:/book/list";
    }
    
    // 查询图书列表
    @GetMapping("/list")
    public String list(Model model) {
        List<Book> books = bookService.getBooks();
        model.addAttribute("books", books);
        return "list";
    }
    
    // 预览图书
    @GetMapping("/preview/{id}")
    public String preview(@PathVariable("id") Long id, Model model) {
        Book book = bookService.getBookById(id);
        model.addAttribute("book", book);
        return "preview";
    }
}

3. 编写Service接口和实现类

public interface BookService {
    void addCategory(String name);
    List<Category> getCategories();
    void addBook(Book book);
    List<Book> getBooks();
    Book getBookById(Long id);
}

@Service
public class BookServiceImpl implements BookService {
    @Autowired
    private CategoryRepository categoryRepository;
    
    @Autowired
    private BookRepository bookRepository;
    
    @Override
    public void addCategory(String name) {
        Category category = new Category();
        category.setName(name);
        categoryRepository.save(category);
    }

    @Override
    public List<Category> getCategories() {
        return categoryRepository.findAll();
    }

    @Override
    public void addBook(Book book) {
        bookRepository.save(book);
    }

    @Override
    public List<Book> getBooks() {
        return bookRepository.findAll();
    }

    @Override
    public Book getBookById(Long id) {
        return bookRepository.findById(id).orElse(null);
    }
}

@Repository
public interface BookRepository extends JpaRepository<Book, Long> {
}

@Repository
public interface CategoryRepository extends JpaRepository<Category, Long> {
}

4. 编写实体类

@Entity
@Table(name = "category")
public class Category {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    private String name;
    
    // getter和setter方法省略
}

@Entity
@Table(name = "book")
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    private String name;
    
    @ManyToOne
    @JoinColumn(name = "category_id")
    private Category category;
    
    private String author;
    
    private String description;
    
    private String cover;
    
    // getter和setter方法省略
}

5. 编写Thymeleaf模板

category.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Book Category</title>
</head>
<body>
    <h2>Add Category</h2>
    <form method="post" action="/book/addCategory">
        <label>Name:</label>
        <input type="text" name="name"/>
        <button type="submit">Add</button>
    </form>
    <hr>
    <h2>Category List</h2>
    <table border="1">
        <tr>
            <th>ID</th>
            <th>Name</th>
        </tr>
        <tr th:each="category : ${categories}">
            <td th:text="${category.id}"></td>
            <td th:text="${category.name}"></td>
        </tr>
    </table>
</body>
</html>

list.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Book List</title>
</head>
<body>
    <h2>Add Book</h2>
    <form method="post" action="/book/addBook" enctype="multipart/form-data">
        <label>Name:</label>
        <input type="text" name="name"/><br>
        <label>Category:</label>
        <select name="category.id">
            <option th:each="category : ${categories}" th:value="${category.id}" th:text="${category.name}"></option>
        </select><br>
        <label>Author:</label>
        <input type="text" name="author"/><br>
        <label>Description:</label>
        <textarea name="description"></textarea><br>
        <label>Cover:</label>
        <input type="file" name="file"/><br>
        <button type="submit">Add</button>
    </form>
    <hr>
    <h2>Book List</h2>
    <table border="1">
        <tr>
            <th>ID</th>
            <th>Name</th>
            <th>Category</th>
            <th>Author</th>
            <th>Description</th>
            <th>Cover</th>
        </tr>
        <tr th:each="book : ${books}">
            <td th:text="${book.id}"></td>
            <td th:text="${book.name}"></td>
            <td th:text="${book.category.name}"></td>
            <td th:text="${book.author}"></td>
            <td th:text="${book.description}"></td>
            <td><img th:src="@{/image/book-covers/__${book.id}__/__${book.cover}__}" width="100"/></td>
        </tr>
    </table>
</body>
</html>

preview.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title th:text="${book.name}"></title>
</head>
<body>
    <h2 th:text="${book.name}"></h2>
    <p th:text="${book.author}"></p>
    <p th:text="${book.description}"></p>
    <img th:src="@{/image/book-covers/__${book.id}__/__${book.cover}__}" width="300"/>
</body>
</html>

6. 编写文件上传工具类

public class FileUploadUtil {
    public static void saveFile(String uploadDir, String fileName, MultipartFile multipartFile) throws IOException {
        Path uploadPath = Paths.get(uploadDir);
        if (!Files.exists(uploadPath)) {
            Files.createDirectories(uploadPath);
        }
        try (InputStream inputStream = multipartFile.getInputStream()) {
            Path filePath = uploadPath.resolve(fileName);
            Files.copy(inputStream, filePath, StandardCopyOption.REPLACE_EXISTING);
        } catch (IOException ex) {
            throw new IOException("Could not save file: " + fileName, ex);
        }
    }
}

以上就是一个简单的JavaWeb在线商城系统的示例代码，希望能对您有所帮助。