维护入口

src/main/java/com/mzh/library/controller/BookManagementServlet.java

@@ -27,6 +27,8 @@ import javax.servlet.http.HttpSession;
 public class BookManagementServlet extends HttpServlet {
     private static final String MANAGE_JSP = "/WEB-INF/jsp/books/manage.jsp";
     private static final String FORM_JSP = "/WEB-INF/jsp/books/form.jsp";
+    private static final String CATEGORY_MANAGE_JSP = "/WEB-INF/jsp/books/categories.jsp";
+    private static final String CATEGORY_FORM_JSP = "/WEB-INF/jsp/books/category-form.jsp";
     private static final String UNAUTHORIZED_JSP = "/WEB-INF/jsp/auth/unauthorized.jsp";
     private static final String FLASH_SUCCESS = "flashSuccess";
     private static final String FLASH_ERROR = "flashError";
@@ -50,6 +52,19 @@ public class BookManagementServlet extends HttpServlet {
             showEditForm(request, response);
             return;
         }
+        if ("/book-categories".equals(path)) {
+            showCategoryList(request, response);
+            return;
+        }
+        if ("/book-categories/new".equals(path)) {
+            renderCategoryForm(request, response, "Create category", "/book-categories", new BookCategory(),
+                Collections.emptyMap(), Collections.emptyMap(), null);
+            return;
+        }
+        if ("/book-categories/edit".equals(path)) {
+            showEditCategoryForm(request, response);
+            return;
+        }
         if (!"/books".equals(path)) {
             response.sendError(HttpServletResponse.SC_NOT_FOUND);
             return;
@@ -73,6 +88,18 @@ public class BookManagementServlet extends HttpServlet {
             deleteBook(request, response);
             return;
         }
+        if ("/book-categories".equals(path)) {
+            createCategory(request, response);
+            return;
+        }
+        if ("/book-categories/update".equals(path)) {
+            updateCategory(request, response);
+            return;
+        }
+        if ("/book-categories/delete".equals(path)) {
+            deleteCategory(request, response);
+            return;
+        }
 
         response.sendError(HttpServletResponse.SC_NOT_FOUND);
     }
@@ -116,6 +143,32 @@ public class BookManagementServlet extends HttpServlet {
             Collections.emptyMap(), Collections.emptyMap(), null);
     }
 
+    private void showCategoryList(HttpServletRequest request, HttpServletResponse response)
+        throws ServletException, IOException {
+        applyFlash(request);
+
+        ServiceResult<List<BookCategory>> result = bookService.listCategories();
+        request.setAttribute("categories", result.isSuccessful() ? result.getData() : Collections.emptyList());
+        if (!result.isSuccessful()) {
+            request.setAttribute("errorMessage", result.getMessage());
+        }
+        request.getRequestDispatcher(CATEGORY_MANAGE_JSP).forward(request, response);
+    }
+
+    private void showEditCategoryForm(HttpServletRequest request, HttpServletResponse response)
+        throws ServletException, IOException {
+        long id = requiredLong(request.getParameter("id"), -1L);
+        ServiceResult<Optional<BookCategory>> result = bookService.findCategory(id);
+        if (!result.isSuccessful() || !result.getData().isPresent()) {
+            flashError(request, result.isSuccessful() ? "Category was not found." : result.getMessage());
+            response.sendRedirect(request.getContextPath() + "/book-categories");
+            return;
+        }
+
+        renderCategoryForm(request, response, "Edit category", "/book-categories/update", result.getData().get(),
+            Collections.emptyMap(), Collections.emptyMap(), null);
+    }
+
     private void createBook(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         BookForm form = readBookForm(request, false);
         if (!form.getErrors().isEmpty()) {
@@ -167,6 +220,60 @@ public class BookManagementServlet extends HttpServlet {
         response.sendRedirect(request.getContextPath() + "/books");
     }
 
+    private void createCategory(HttpServletRequest request, HttpServletResponse response)
+        throws ServletException, IOException {
+        CategoryForm form = readCategoryForm(request, false);
+        if (!form.getErrors().isEmpty()) {
+            renderCategoryForm(request, response, "Create category", "/book-categories", form.getCategory(),
+                form.getValues(), form.getErrors(), "Please correct the highlighted category fields.");
+            return;
+        }
+
+        ServiceResult<Long> result = bookService.createCategory(currentUser(request), form.getCategory());
+        if (!result.isSuccessful()) {
+            handleCategoryFormFailure(request, response, "Create category", "/book-categories", form, result);
+            return;
+        }
+
+        flashSuccess(request, result.getMessage());
+        response.sendRedirect(request.getContextPath() + "/book-categories");
+    }
+
+    private void updateCategory(HttpServletRequest request, HttpServletResponse response)
+        throws ServletException, IOException {
+        CategoryForm form = readCategoryForm(request, true);
+        if (!form.getErrors().isEmpty()) {
+            renderCategoryForm(request, response, "Edit category", "/book-categories/update", form.getCategory(),
+                form.getValues(), form.getErrors(), "Please correct the highlighted category fields.");
+            return;
+        }
+
+        ServiceResult<Void> result = bookService.updateCategory(currentUser(request), form.getCategory());
+        if (!result.isSuccessful()) {
+            handleCategoryFormFailure(request, response, "Edit category", "/book-categories/update", form, result);
+            return;
+        }
+
+        flashSuccess(request, result.getMessage());
+        response.sendRedirect(request.getContextPath() + "/book-categories");
+    }
+
+    private void deleteCategory(HttpServletRequest request, HttpServletResponse response)
+        throws IOException, ServletException {
+        long id = requiredLong(request.getParameter("id"), -1L);
+        ServiceResult<Void> result = bookService.deleteCategory(currentUser(request), id);
+        if (isPermissionDenied(result)) {
+            forwardDenied(request, response, result.getMessage());
+            return;
+        }
+        if (result.isSuccessful()) {
+            flashSuccess(request, result.getMessage());
+        } else {
+            flashError(request, result.getMessage());
+        }
+        response.sendRedirect(request.getContextPath() + "/book-categories");
+    }
+
     private void handleFormFailure(HttpServletRequest request, HttpServletResponse response, String title,
                                    String action, BookForm form, ServiceResult<?> result)
         throws ServletException, IOException {
@@ -178,6 +285,17 @@ public class BookManagementServlet extends HttpServlet {
             result.getMessage());
     }
 
+    private void handleCategoryFormFailure(HttpServletRequest request, HttpServletResponse response, String title,
+                                           String action, CategoryForm form, ServiceResult<?> result)
+        throws ServletException, IOException {
+        if (isPermissionDenied(result)) {
+            forwardDenied(request, response, result.getMessage());
+            return;
+        }
+        renderCategoryForm(request, response, title, action, form.getCategory(), form.getValues(),
+            result.getErrors(), result.getMessage());
+    }
+
     private void renderForm(HttpServletRequest request, HttpServletResponse response, String title, String action,
                             Book book, Map<String, String> formValues, Map<String, String> errors, String errorMessage)
         throws ServletException, IOException {
@@ -199,6 +317,21 @@ public class BookManagementServlet extends HttpServlet {
         request.getRequestDispatcher(FORM_JSP).forward(request, response);
     }
 
+    private void renderCategoryForm(HttpServletRequest request, HttpServletResponse response, String title,
+                                    String action, BookCategory category, Map<String, String> formValues,
+                                    Map<String, String> errors, String errorMessage)
+        throws ServletException, IOException {
+        request.setAttribute("formTitle", title);
+        request.setAttribute("formAction", action);
+        request.setAttribute("category", category);
+        request.setAttribute("formValues", formValues);
+        request.setAttribute("errors", errors);
+        if (errorMessage != null && !errorMessage.isEmpty()) {
+            request.setAttribute("errorMessage", errorMessage);
+        }
+        request.getRequestDispatcher(CATEGORY_FORM_JSP).forward(request, response);
+    }
+
     private BookForm readBookForm(HttpServletRequest request, boolean requireId) {
         Map<String, String> values = formValues(request);
         Map<String, String> errors = new LinkedHashMap<>();
@@ -237,6 +370,27 @@ public class BookManagementServlet extends HttpServlet {
         return values;
     }
 
+    private CategoryForm readCategoryForm(HttpServletRequest request, boolean requireId) {
+        Map<String, String> values = categoryFormValues(request);
+        Map<String, String> errors = new LinkedHashMap<>();
+        BookCategory category = new BookCategory();
+
+        if (requireId) {
+            category.setId(parseLong(values.get("id"), "id", "Select a valid category.", errors));
+        }
+        category.setName(values.get("name"));
+        category.setDescription(values.get("description"));
+        return new CategoryForm(category, values, errors);
+    }
+
+    private Map<String, String> categoryFormValues(HttpServletRequest request) {
+        Map<String, String> values = new LinkedHashMap<>();
+        values.put("id", trim(request.getParameter("id")));
+        values.put("name", trim(request.getParameter("name")));
+        values.put("description", trim(request.getParameter("description")));
+        return values;
+    }
+
     private BookSearchCriteria searchCriteria(HttpServletRequest request) {
         return new BookSearchCriteria(
             request.getParameter("identifier"),
@@ -368,4 +522,28 @@ public class BookManagementServlet extends HttpServlet {
             return errors;
         }
     }
+
+    private static final class CategoryForm {
+        private final BookCategory category;
+        private final Map<String, String> values;
+        private final Map<String, String> errors;
+
+        private CategoryForm(BookCategory category, Map<String, String> values, Map<String, String> errors) {
+            this.category = category;
+            this.values = values;
+            this.errors = errors;
+        }
+
+        private BookCategory getCategory() {
+            return category;
+        }
+
+        private Map<String, String> getValues() {
+            return values;
+        }
+
+        private Map<String, String> getErrors() {
+            return errors;
+        }
+    }
 }

src/main/java/com/mzh/library/dao/BookDao.java

@@ -10,6 +10,18 @@ import java.util.Optional;
 public interface BookDao {
     List<BookCategory> findAllCategories();
 
+    Optional<BookCategory> findCategoryById(long id);
+
+    Optional<BookCategory> findCategoryByName(String name);
+
+    long createCategory(BookCategory category);
+
+    boolean updateCategory(BookCategory category);
+
+    boolean deleteCategory(long id);
+
+    int countBooksByCategoryId(long categoryId);
+
     List<Book> search(BookSearchCriteria criteria);
 
     Optional<Book> findById(long id);

src/main/java/com/mzh/library/dao/impl/JdbcBookDao.java

@@ -33,6 +33,32 @@ public class JdbcBookDao implements BookDao {
         + "FROM book_categories "
         + "ORDER BY name";
 
+    private static final String FIND_CATEGORY_BY_ID = ""
+        + "SELECT id, name, description "
+        + "FROM book_categories "
+        + "WHERE id = ?";
+
+    private static final String FIND_CATEGORY_BY_NAME = ""
+        + "SELECT id, name, description "
+        + "FROM book_categories "
+        + "WHERE name = ?";
+
+    private static final String CREATE_CATEGORY = ""
+        + "INSERT INTO book_categories (name, description) "
+        + "VALUES (?, ?)";
+
+    private static final String UPDATE_CATEGORY = ""
+        + "UPDATE book_categories "
+        + "SET name = ?, description = ? "
+        + "WHERE id = ?";
+
+    private static final String DELETE_CATEGORY = "DELETE FROM book_categories WHERE id = ?";
+
+    private static final String COUNT_BOOKS_BY_CATEGORY = ""
+        + "SELECT COUNT(*) "
+        + "FROM books "
+        + "WHERE category_id = ?";
+
     private static final String FIND_BY_ID = "SELECT " + BOOK_COLUMNS + BOOK_FROM + "WHERE b.id = ?";
 
     private static final String FIND_BY_IDENTIFIER = "SELECT " + BOOK_COLUMNS + BOOK_FROM
@@ -66,6 +92,86 @@ public class JdbcBookDao implements BookDao {
         }
     }
 
+    @Override
+    public Optional<BookCategory> findCategoryById(long id) {
+        try (Connection connection = JdbcUtil.getConnection();
+             PreparedStatement statement = connection.prepareStatement(FIND_CATEGORY_BY_ID)) {
+            statement.setLong(1, id);
+            try (ResultSet resultSet = statement.executeQuery()) {
+                return resultSet.next() ? Optional.of(mapCategory(resultSet)) : Optional.empty();
+            }
+        } catch (SQLException ex) {
+            throw new DaoException("Unable to load book category by id", ex);
+        }
+    }
+
+    @Override
+    public Optional<BookCategory> findCategoryByName(String name) {
+        try (Connection connection = JdbcUtil.getConnection();
+             PreparedStatement statement = connection.prepareStatement(FIND_CATEGORY_BY_NAME)) {
+            statement.setString(1, name);
+            try (ResultSet resultSet = statement.executeQuery()) {
+                return resultSet.next() ? Optional.of(mapCategory(resultSet)) : Optional.empty();
+            }
+        } catch (SQLException ex) {
+            throw new DaoException("Unable to load book category by name", ex);
+        }
+    }
+
+    @Override
+    public long createCategory(BookCategory category) {
+        try (Connection connection = JdbcUtil.getConnection();
+             PreparedStatement statement = connection.prepareStatement(CREATE_CATEGORY, Statement.RETURN_GENERATED_KEYS)) {
+            bindCategory(statement, category);
+            statement.executeUpdate();
+
+            try (ResultSet generatedKeys = statement.getGeneratedKeys()) {
+                if (generatedKeys.next()) {
+                    return generatedKeys.getLong(1);
+                }
+            }
+            throw new DaoException("Unable to read generated book category id", null);
+        } catch (SQLException ex) {
+            throw new DaoException("Unable to create book category", ex);
+        }
+    }
+
+    @Override
+    public boolean updateCategory(BookCategory category) {
+        try (Connection connection = JdbcUtil.getConnection();
+             PreparedStatement statement = connection.prepareStatement(UPDATE_CATEGORY)) {
+            bindCategory(statement, category);
+            statement.setLong(3, category.getId());
+            return statement.executeUpdate() == 1;
+        } catch (SQLException ex) {
+            throw new DaoException("Unable to update book category", ex);
+        }
+    }
+
+    @Override
+    public boolean deleteCategory(long id) {
+        try (Connection connection = JdbcUtil.getConnection();
+             PreparedStatement statement = connection.prepareStatement(DELETE_CATEGORY)) {
+            statement.setLong(1, id);
+            return statement.executeUpdate() == 1;
+        } catch (SQLException ex) {
+            throw new DaoException("Unable to delete book category", ex);
+        }
+    }
+
+    @Override
+    public int countBooksByCategoryId(long categoryId) {
+        try (Connection connection = JdbcUtil.getConnection();
+             PreparedStatement statement = connection.prepareStatement(COUNT_BOOKS_BY_CATEGORY)) {
+            statement.setLong(1, categoryId);
+            try (ResultSet resultSet = statement.executeQuery()) {
+                return resultSet.next() ? resultSet.getInt(1) : 0;
+            }
+        } catch (SQLException ex) {
+            throw new DaoException("Unable to count books by category", ex);
+        }
+    }
+
     @Override
     public List<Book> search(BookSearchCriteria criteria) {
         List<Object> parameters = new ArrayList<>();
@@ -194,6 +300,11 @@ public class JdbcBookDao implements BookDao {
         statement.setString(7, book.getStatus().getCode());
     }
 
+    private void bindCategory(PreparedStatement statement, BookCategory category) throws SQLException {
+        statement.setString(1, category.getName());
+        statement.setString(2, category.getDescription());
+    }
+
     private Book mapBook(ResultSet resultSet) throws SQLException {
         Book book = new Book();
         book.setId(resultSet.getLong("id"));

src/main/java/com/mzh/library/filter/AuthorizationFilter.java

@@ -29,6 +29,7 @@ public class AuthorizationFilter implements Filter {
         new PathRule("/admin/system-logs", Permission.VIEW_SYSTEM_LOGS),
         new PathRule("/reports", Permission.VIEW_REPORTS),
         new PathRule("/borrowing", Permission.MANAGE_BORROWING),
+        new PathRule("/book-categories", Permission.MANAGE_BOOKS),
         new PathRule("/books", Permission.MANAGE_BOOKS),
         new PathRule("/readers", Permission.MANAGE_READERS),
         new PathRule("/catalog", Permission.VIEW_CATALOG),

src/main/java/com/mzh/library/service/BookService.java

@@ -11,6 +11,14 @@ import java.util.Optional;
 public interface BookService {
     ServiceResult<List<BookCategory>> listCategories();
 
+    ServiceResult<Optional<BookCategory>> findCategory(long id);
+
+    ServiceResult<Long> createCategory(AuthenticatedUser actor, BookCategory category);
+
+    ServiceResult<Void> updateCategory(AuthenticatedUser actor, BookCategory category);
+
+    ServiceResult<Void> deleteCategory(AuthenticatedUser actor, long id);
+
     ServiceResult<List<Book>> searchBooks(BookSearchCriteria criteria);
 
     ServiceResult<Optional<Book>> findBook(long id);

src/main/java/com/mzh/library/service/impl/BookServiceImpl.java

@@ -23,6 +23,7 @@ public class BookServiceImpl implements BookService {
     private static final String UNAVAILABLE_MESSAGE =
         "Book service is temporarily unavailable. Please try again later.";
     private static final String VALIDATION_MESSAGE = "Please correct the highlighted book fields.";
+    private static final String CATEGORY_VALIDATION_MESSAGE = "Please correct the highlighted category fields.";
     private static final String DENIED_MESSAGE = "You do not have permission to manage books.";
 
     private final BookDao bookDao;
@@ -47,6 +48,111 @@ public class BookServiceImpl implements BookService {
         }
     }
 
+    @Override
+    public ServiceResult<Optional<BookCategory>> findCategory(long id) {
+        if (id <= 0) {
+            return ServiceResult.failure("Select a valid category.");
+        }
+
+        try {
+            return ServiceResult.success(bookDao.findCategoryById(id));
+        } catch (DaoException ex) {
+            LOGGER.log(Level.SEVERE, "Unable to load book category id=" + id, ex);
+            return ServiceResult.failure(UNAVAILABLE_MESSAGE);
+        }
+    }
+
+    @Override
+    public ServiceResult<Long> createCategory(AuthenticatedUser actor, BookCategory category) {
+        if (!canManageBooks(actor)) {
+            return ServiceResult.failure(DENIED_MESSAGE);
+        }
+
+        normalize(category);
+        Map<String, String> errors = validate(category, false);
+        if (!errors.isEmpty()) {
+            return ServiceResult.validationFailure(CATEGORY_VALIDATION_MESSAGE, errors);
+        }
+
+        try {
+            if (bookDao.findCategoryByName(category.getName()).isPresent()) {
+                errors.put("name", "Category name is already in use.");
+                return ServiceResult.validationFailure(CATEGORY_VALIDATION_MESSAGE, errors);
+            }
+
+            long id = bookDao.createCategory(category);
+            LOGGER.info("Created book category id=" + id + " actorId=" + actor.getId());
+            return ServiceResult.success(id, "Category created.");
+        } catch (DaoException ex) {
+            LOGGER.log(Level.SEVERE, "Unable to create book category actorId=" + actor.getId()
+                + " name=" + safeCategoryName(category), ex);
+            return ServiceResult.failure(UNAVAILABLE_MESSAGE);
+        }
+    }
+
+    @Override
+    public ServiceResult<Void> updateCategory(AuthenticatedUser actor, BookCategory category) {
+        if (!canManageBooks(actor)) {
+            return ServiceResult.failure(DENIED_MESSAGE);
+        }
+
+        normalize(category);
+        Map<String, String> errors = validate(category, true);
+        if (!errors.isEmpty()) {
+            return ServiceResult.validationFailure(CATEGORY_VALIDATION_MESSAGE, errors);
+        }
+
+        try {
+            Optional<BookCategory> existingWithName = bookDao.findCategoryByName(category.getName());
+            if (existingWithName.isPresent() && existingWithName.get().getId() != category.getId()) {
+                errors.put("name", "Category name is already in use.");
+                return ServiceResult.validationFailure(CATEGORY_VALIDATION_MESSAGE, errors);
+            }
+
+            if (!bookDao.updateCategory(category)) {
+                return ServiceResult.failure("Category was not found.");
+            }
+
+            LOGGER.info("Updated book category id=" + category.getId() + " actorId=" + actor.getId());
+            return ServiceResult.success(null, "Category updated.");
+        } catch (DaoException ex) {
+            LOGGER.log(Level.SEVERE, "Unable to update book category id=" + category.getId()
+                + " actorId=" + actor.getId(), ex);
+            return ServiceResult.failure(UNAVAILABLE_MESSAGE);
+        }
+    }
+
+    @Override
+    public ServiceResult<Void> deleteCategory(AuthenticatedUser actor, long id) {
+        if (!canManageBooks(actor)) {
+            return ServiceResult.failure(DENIED_MESSAGE);
+        }
+        if (id <= 0) {
+            return ServiceResult.failure("Select a valid category.");
+        }
+
+        try {
+            if (!bookDao.findCategoryById(id).isPresent()) {
+                return ServiceResult.failure("Category was not found.");
+            }
+            if (bookDao.countBooksByCategoryId(id) > 0) {
+                Map<String, String> errors = new LinkedHashMap<>();
+                errors.put("category", "Category is used by existing books and cannot be deleted.");
+                return ServiceResult.validationFailure("Category is used by existing books and cannot be deleted.",
+                    errors);
+            }
+            if (!bookDao.deleteCategory(id)) {
+                return ServiceResult.failure("Category was not found.");
+            }
+
+            LOGGER.info("Deleted book category id=" + id + " actorId=" + actor.getId());
+            return ServiceResult.success(null, "Category deleted.");
+        } catch (DaoException ex) {
+            LOGGER.log(Level.SEVERE, "Unable to delete book category id=" + id + " actorId=" + actor.getId(), ex);
+            return ServiceResult.failure(UNAVAILABLE_MESSAGE);
+        }
+    }
+
     @Override
     public ServiceResult<List<Book>> searchBooks(BookSearchCriteria criteria) {
         BookSearchCriteria normalized = criteria == null ? new BookSearchCriteria() : criteria;
@@ -171,6 +277,14 @@ public class BookServiceImpl implements BookService {
         book.setAuthor(trim(book.getAuthor()));
     }
 
+    private void normalize(BookCategory category) {
+        if (category == null) {
+            return;
+        }
+        category.setName(trim(category.getName()));
+        category.setDescription(trim(category.getDescription()));
+    }
+
     private Map<String, String> validate(Book book, boolean requireId) {
         Map<String, String> errors = new LinkedHashMap<>();
         if (book == null) {
@@ -202,6 +316,27 @@ public class BookServiceImpl implements BookService {
         return errors;
     }
 
+    private Map<String, String> validate(BookCategory category, boolean requireId) {
+        Map<String, String> errors = new LinkedHashMap<>();
+        if (category == null) {
+            errors.put("category", "Category details are required.");
+            return errors;
+        }
+
+        if (requireId && category.getId() <= 0) {
+            errors.put("id", "Select a valid category.");
+        }
+        requireLength(errors, "name", category.getName(), "Category name", 96);
+        if (category.getDescription() != null && category.getDescription().length() > 255) {
+            errors.put("description", "Description must be 255 characters or fewer.");
+        }
+        return errors;
+    }
+
+    private String safeCategoryName(BookCategory category) {
+        return category == null ? "" : category.getName();
+    }
+
     private void requireLength(Map<String, String> errors, String field, String value, String label, int maxLength) {
         if (value == null || value.isEmpty()) {
             errors.put(field, label + " is required.");

src/main/webapp/WEB-INF/jsp/books/categories.jsp

@@ -0,0 +1,89 @@
+<%@ page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>
+<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>Manage Categories - MZH Library</title>
+    <link rel="stylesheet" href="${pageContext.request.contextPath}/static/css/app.css">
+</head>
+<body>
+<%@ include file="/WEB-INF/jsp/common/header.jspf" %>
+<main class="page-shell">
+    <section class="dashboard-hero catalog-hero" aria-labelledby="category-title">
+        <div>
+            <p class="eyebrow">Book Management</p>
+            <h1 id="category-title">Manage categories</h1>
+            <p>Maintain catalog groupings used by book records and search filters.</p>
+        </div>
+        <div class="hero-actions">
+            <a class="button button-primary" href="${pageContext.request.contextPath}/book-categories/new">New category</a>
+            <a class="button button-secondary" href="${pageContext.request.contextPath}/books">Manage books</a>
+        </div>
+    </section>
+
+    <c:if test="${not empty successMessage}">
+        <div class="message message-success" role="status">
+            <c:out value="${successMessage}" />
+        </div>
+    </c:if>
+    <c:if test="${not empty errorMessage}">
+        <div class="message message-error" role="alert">
+            <c:out value="${errorMessage}" />
+        </div>
+    </c:if>
+
+    <section class="table-panel" aria-labelledby="category-results-title">
+        <h2 id="category-results-title">Category records</h2>
+        <c:choose>
+            <c:when test="${empty categories}">
+                <p class="empty-state">No categories have been created yet.</p>
+            </c:when>
+            <c:otherwise>
+                <div class="table-scroll">
+                    <table class="data-table category-table">
+                        <thead>
+                        <tr>
+                            <th scope="col">Name</th>
+                            <th scope="col">Description</th>
+                            <th scope="col">Actions</th>
+                        </tr>
+                        </thead>
+                        <tbody>
+                        <c:forEach var="category" items="${categories}">
+                            <tr>
+                                <td><c:out value="${category.name}" /></td>
+                                <td>
+                                    <c:choose>
+                                        <c:when test="${empty category.description}">
+                                            <span class="muted-text">No description</span>
+                                        </c:when>
+                                        <c:otherwise>
+                                            <c:out value="${category.description}" />
+                                        </c:otherwise>
+                                    </c:choose>
+                                </td>
+                                <td>
+                                    <div class="table-actions">
+                                        <a class="button button-secondary"
+                                           href="${pageContext.request.contextPath}/book-categories/edit?id=${category.id}">Edit</a>
+                                        <form action="${pageContext.request.contextPath}/book-categories/delete"
+                                              method="post"
+                                              onsubmit="return confirm('Delete this category?');">
+                                            <input type="hidden" name="id" value="${category.id}">
+                                            <button class="button button-danger" type="submit">Delete</button>
+                                        </form>
+                                    </div>
+                                </td>
+                            </tr>
+                        </c:forEach>
+                        </tbody>
+                    </table>
+                </div>
+            </c:otherwise>
+        </c:choose>
+    </section>
+</main>
+</body>
+</html>

src/main/webapp/WEB-INF/jsp/books/category-form.jsp

@@ -0,0 +1,66 @@
+<%@ page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" %>
+<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
+<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title><c:out value="${formTitle}" /> - MZH Library</title>
+    <link rel="stylesheet" href="${pageContext.request.contextPath}/static/css/app.css">
+</head>
+<body>
+<%@ include file="/WEB-INF/jsp/common/header.jspf" %>
+<main class="page-shell">
+    <section class="form-panel" aria-labelledby="category-form-title">
+        <p class="eyebrow">Book Management</p>
+        <h1 id="category-form-title"><c:out value="${formTitle}" /></h1>
+
+        <c:if test="${not empty errorMessage}">
+            <div class="message message-error" role="alert">
+                <c:out value="${errorMessage}" />
+            </div>
+        </c:if>
+
+        <c:set var="hasFormValues" value="${not empty formValues}" />
+        <c:set var="nameValue" value="${hasFormValues ? formValues.name : category.name}" />
+        <c:set var="descriptionValue" value="${hasFormValues ? formValues.description : category.description}" />
+
+        <form class="category-form" action="${pageContext.request.contextPath}${formAction}" method="post" novalidate>
+            <c:if test="${category.id > 0}">
+                <input type="hidden" name="id" value="${category.id}">
+            </c:if>
+
+            <div class="form-grid">
+                <div class="form-field">
+                    <label for="name">Category name</label>
+                    <input id="name" name="name" type="text" value="${fn:escapeXml(nameValue)}" required>
+                    <c:if test="${not empty errors.name}">
+                        <span class="field-error"><c:out value="${errors.name}" /></span>
+                    </c:if>
+                </div>
+
+                <div class="form-field form-field-wide">
+                    <label for="description">Description</label>
+                    <textarea id="description" name="description" rows="4">${fn:escapeXml(descriptionValue)}</textarea>
+                    <c:if test="${not empty errors.description}">
+                        <span class="field-error"><c:out value="${errors.description}" /></span>
+                    </c:if>
+                </div>
+            </div>
+
+            <c:if test="${not empty errors.category}">
+                <div class="message message-error" role="alert">
+                    <c:out value="${errors.category}" />
+                </div>
+            </c:if>
+
+            <div class="form-actions">
+                <button class="button button-primary" type="submit">Save</button>
+                <a class="button button-secondary" href="${pageContext.request.contextPath}/book-categories">Cancel</a>
+            </div>
+        </form>
+    </section>
+</main>
+</body>
+</html>

src/main/webapp/WEB-INF/jsp/books/manage.jsp

@@ -16,7 +16,10 @@
         <p class="eyebrow">Book Management</p>
         <h1 id="manage-title">Manage books</h1>
         <p>Create, update, delete, and review inventory for catalog records.</p>
-        <a class="button button-primary" href="${pageContext.request.contextPath}/books/new">New book</a>
+        <div class="hero-actions">
+            <a class="button button-primary" href="${pageContext.request.contextPath}/books/new">New book</a>
+            <a class="button button-secondary" href="${pageContext.request.contextPath}/book-categories">Categories</a>
+        </div>
     </section>
 
     <c:if test="${not empty successMessage}">
@@ -65,6 +68,7 @@
             <button class="button button-primary" type="submit">Search</button>
             <a class="button button-secondary" href="${pageContext.request.contextPath}/books">Clear</a>
             <a class="button button-secondary" href="${pageContext.request.contextPath}/catalog">View catalog</a>
+            <a class="button button-secondary" href="${pageContext.request.contextPath}/book-categories">Categories</a>
         </form>
     </section>
 

src/main/webapp/WEB-INF/jsp/common/header.jspf

@@ -13,6 +13,7 @@
             <c:if test="${sessionScope.userRole == 'administrator' or sessionScope.userRole == 'librarian'}">
                 <a href="${pageContext.request.contextPath}/librarian/home">Librarian</a>
                 <a href="${pageContext.request.contextPath}/books">Books</a>
+                <a href="${pageContext.request.contextPath}/book-categories">Categories</a>
                 <a href="${pageContext.request.contextPath}/readers">Readers</a>
                 <a href="${pageContext.request.contextPath}/borrowing">Borrowing</a>
                 <a href="${pageContext.request.contextPath}/reports">Reports</a>

src/main/webapp/WEB-INF/jsp/dashboard.jsp

@@ -53,6 +53,12 @@
                 <a class="button button-secondary" href="${pageContext.request.contextPath}/books">Open</a>
             </article>
 
+            <article class="workspace-card">
+                <h2>Category Maintenance</h2>
+                <p>Maintain catalog categories used by book records and search filters.</p>
+                <a class="button button-secondary" href="${pageContext.request.contextPath}/book-categories">Open</a>
+            </article>
+
             <article class="workspace-card">
                 <h2>Reader Management</h2>
                 <p>Create, update, deactivate, and review reader eligibility records.</p>

src/main/webapp/WEB-INF/jsp/role-home.jsp

@@ -48,6 +48,12 @@
                 <a class="button button-secondary" href="${pageContext.request.contextPath}/books">Manage books</a>
             </article>
 
+            <article class="workspace-card">
+                <h2>Category Maintenance</h2>
+                <p>Create, update, and retire catalog categories used by book records.</p>
+                <a class="button button-secondary" href="${pageContext.request.contextPath}/book-categories">Manage categories</a>
+            </article>
+
             <article class="workspace-card">
                 <h2>Reader Management</h2>
                 <p>Create, update, deactivate, and review eligibility fields for reader records.</p>

src/main/webapp/WEB-INF/web.xml

@@ -117,6 +117,11 @@
         <url-pattern>/books/edit</url-pattern>
         <url-pattern>/books/update</url-pattern>
         <url-pattern>/books/delete</url-pattern>
+        <url-pattern>/book-categories</url-pattern>
+        <url-pattern>/book-categories/new</url-pattern>
+        <url-pattern>/book-categories/edit</url-pattern>
+        <url-pattern>/book-categories/update</url-pattern>
+        <url-pattern>/book-categories/delete</url-pattern>
     </servlet-mapping>
 
     <servlet>

src/main/webapp/static/css/app.css

@@ -313,6 +313,12 @@ h2 {
     margin-top: 0;
 }
 
+.hero-actions {
+    display: flex;
+    gap: 10px;
+    flex-wrap: wrap;
+}
+
 .toolbar-panel,
 .table-panel,
 .form-panel {
@@ -350,6 +356,8 @@ h2 {
 .search-form select,
 .book-form input,
 .book-form select,
+.category-form input,
+.category-form textarea,
 .reader-form input,
 .reader-form select,
 .user-form input,
@@ -368,6 +376,8 @@ h2 {
 .search-form select:focus,
 .book-form input:focus,
 .book-form select:focus,
+.category-form input:focus,
+.category-form textarea:focus,
 .reader-form input:focus,
 .reader-form select:focus,
 .user-form input:focus,
@@ -394,7 +404,8 @@ h2 {
 }
 
 .user-table,
-.system-log-table {
+.system-log-table,
+.category-table {
     min-width: 980px;
 }
 
@@ -504,6 +515,7 @@ h2 {
 }
 
 .book-form,
+.category-form,
 .reader-form,
 .user-form,
 .borrow-form {
@@ -522,6 +534,15 @@ h2 {
     gap: 6px;
 }
 
+.form-field-wide {
+    grid-column: 1 / -1;
+}
+
+.category-form textarea {
+    min-height: 112px;
+    resize: vertical;
+}
+
 .form-field label {
     color: var(--color-muted);
     font-size: 14px;

src/test/java/com/mzh/library/service/BookServiceCheck.java

@@ -12,7 +12,6 @@ import com.mzh.library.exception.DaoException;
 import com.mzh.library.service.impl.BookServiceImpl;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.EnumSet;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -48,6 +47,12 @@ public final class BookServiceCheck {
         require("You do not have permission to manage books.".equals(denied.getMessage()),
             "reader write should return permission message");
 
+        ServiceResult<Long> deniedCategory = service.createCategory(reader,
+            category(0L, "Reader Category", "Denied category"));
+        require(!deniedCategory.isSuccessful(), "reader category create should fail");
+        require("You do not have permission to manage books.".equals(deniedCategory.getMessage()),
+            "reader category write should return permission message");
+
         ServiceResult<Long> created = service.createBook(librarian,
             book(0L, "BK-1002", "Service Test", "Test Author", 1L, 2, 1, BookStatus.AVAILABLE));
         require(created.isSuccessful(), "librarian should create a valid book");
@@ -63,6 +68,13 @@ public final class BookServiceCheck {
         require(updated.isSuccessful(), "librarian should update a valid book");
         require(dao.findById(createdId).get().getAvailableCopies() == 3, "update should persist available copies");
 
+        ServiceResult<Void> deleteUsedCategory = service.deleteCategory(librarian, 1L);
+        require(!deleteUsedCategory.isSuccessful(), "used category delete should fail");
+        require("Category is used by existing books and cannot be deleted.".equals(deleteUsedCategory.getMessage()),
+            "used category delete should return a safe specific message");
+        require(deleteUsedCategory.getErrors().containsKey("category"),
+            "used category delete should return a category-level field error");
+
         ServiceResult<List<Book>> search = service.searchBooks(new BookSearchCriteria("BK-1003", "", "", null));
         require(search.isSuccessful(), "search should succeed");
         require(search.getData().size() == 1, "search should find updated identifier");
@@ -71,6 +83,26 @@ public final class BookServiceCheck {
         require(deleted.isSuccessful(), "librarian should delete a book");
         require(!dao.findById(createdId).isPresent(), "delete should remove the record");
 
+        ServiceResult<Long> createdCategory = service.createCategory(librarian,
+            category(0L, "Architecture", "Design and systems"));
+        require(createdCategory.isSuccessful(), "librarian should create a category");
+        long categoryId = createdCategory.getData();
+
+        ServiceResult<Long> duplicateCategory = service.createCategory(librarian,
+            category(0L, "Architecture", "Duplicate category"));
+        require(!duplicateCategory.isSuccessful(), "duplicate category should fail");
+        require(duplicateCategory.getErrors().containsKey("name"), "duplicate category should target name field");
+
+        ServiceResult<Void> updatedCategory = service.updateCategory(librarian,
+            category(categoryId, "Software Architecture", "Updated category"));
+        require(updatedCategory.isSuccessful(), "librarian should update a category");
+        require("Software Architecture".equals(dao.findCategoryById(categoryId).get().getName()),
+            "category update should persist the new name");
+
+        ServiceResult<Void> deletedCategory = service.deleteCategory(librarian, categoryId);
+        require(deletedCategory.isSuccessful(), "unused category should be deleted");
+        require(!dao.findCategoryById(categoryId).isPresent(), "category delete should remove unused category");
+
         BookService failingService = new BookServiceImpl(new FailingBookDao());
         ServiceResult<List<Book>> unavailable = failingService.searchBooks(new BookSearchCriteria());
         require(!unavailable.isSuccessful(), "DAO failure should not escape service");
@@ -98,6 +130,14 @@ public final class BookServiceCheck {
         return book;
     }
 
+    private static BookCategory category(long id, String name, String description) {
+        BookCategory category = new BookCategory();
+        category.setId(id);
+        category.setName(name);
+        category.setDescription(description);
+        return category;
+    }
+
     private static void require(boolean condition, String message) {
         if (!condition) {
             throw new AssertionError(message);
@@ -106,14 +146,70 @@ public final class BookServiceCheck {
 
     private static final class InMemoryBookDao implements BookDao {
         private final Map<Long, Book> books = new LinkedHashMap<>();
+        private final Map<Long, BookCategory> categories = new LinkedHashMap<>();
         private long nextId = 1L;
+        private long nextCategoryId = 2L;
+
+        private InMemoryBookDao() {
+            categories.put(1L, category(1L, "Computer Science", "Programming books"));
+        }
 
         @Override
         public List<BookCategory> findAllCategories() {
-            BookCategory category = new BookCategory();
-            category.setId(1L);
-            category.setName("Computer Science");
-            return Collections.singletonList(category);
+            List<BookCategory> results = new ArrayList<>();
+            for (BookCategory category : categories.values()) {
+                results.add(copy(category));
+            }
+            return results;
+        }
+
+        @Override
+        public Optional<BookCategory> findCategoryById(long id) {
+            return Optional.ofNullable(categories.get(id)).map(this::copy);
+        }
+
+        @Override
+        public Optional<BookCategory> findCategoryByName(String name) {
+            for (BookCategory category : categories.values()) {
+                if (category.getName().equals(name)) {
+                    return Optional.of(copy(category));
+                }
+            }
+            return Optional.empty();
+        }
+
+        @Override
+        public long createCategory(BookCategory category) {
+            long id = nextCategoryId++;
+            BookCategory stored = copy(category);
+            stored.setId(id);
+            categories.put(id, stored);
+            return id;
+        }
+
+        @Override
+        public boolean updateCategory(BookCategory category) {
+            if (!categories.containsKey(category.getId())) {
+                return false;
+            }
+            categories.put(category.getId(), copy(category));
+            return true;
+        }
+
+        @Override
+        public boolean deleteCategory(long id) {
+            return categories.remove(id) != null;
+        }
+
+        @Override
+        public int countBooksByCategoryId(long categoryId) {
+            int count = 0;
+            for (Book book : books.values()) {
+                if (book.getCategoryId() == categoryId) {
+                    count++;
+                }
+            }
+            return count;
         }
 
         @Override
@@ -178,6 +274,10 @@ public final class BookServiceCheck {
             copy.setCategoryName(source.getCategoryName());
             return copy;
         }
+
+        private BookCategory copy(BookCategory source) {
+            return category(source.getId(), source.getName(), source.getDescription());
+        }
     }
 
     private static final class FailingBookDao implements BookDao {
@@ -186,6 +286,36 @@ public final class BookServiceCheck {
             throw new DaoException("Simulated category failure", null);
         }
 
+        @Override
+        public Optional<BookCategory> findCategoryById(long id) {
+            throw new DaoException("Simulated category find failure", null);
+        }
+
+        @Override
+        public Optional<BookCategory> findCategoryByName(String name) {
+            throw new DaoException("Simulated category find failure", null);
+        }
+
+        @Override
+        public long createCategory(BookCategory category) {
+            throw new DaoException("Simulated category create failure", null);
+        }
+
+        @Override
+        public boolean updateCategory(BookCategory category) {
+            throw new DaoException("Simulated category update failure", null);
+        }
+
+        @Override
+        public boolean deleteCategory(long id) {
+            throw new DaoException("Simulated category delete failure", null);
+        }
+
+        @Override
+        public int countBooksByCategoryId(long categoryId) {
+            throw new DaoException("Simulated category count failure", null);
+        }
+
         @Override
         public List<Book> search(BookSearchCriteria criteria) {
             throw new DaoException("Simulated search failure", null);