Question

我正在尝试创建/删除/更新图书的CRUD + spring应用程序。一切正常，但从数据库中搜索一本书。请帮忙。

@Controller
public class BookController {
...................
    @RequestMapping("searchBook")
    public ModelAndView searchBook(@RequestParam("searchBook") String title){
        List<Book> booksList = bookService.getAllBooks(title);
        return new ModelAndView("booksearch", "booksList", booksList);
    }
}

有一个books.jsp：     ...................
    返回主菜单

按标题搜索书籍：

                                                   ID                 标题                 作者                 描述                 国际标准书号                 打印年份                 已经阅读了                 编辑                 删除                                                                                          $ {} book.id                     $ {} book.bookTitle                     $ {} book.bookAuthor                     $ {} book.description                     $ {} book.isbn                     $ {} book.printYear                     $ {} book.readAlready                     ＆＃34;＆gt;编辑                     ＆＃34;＆GT;删除                                                              **我的项目有一个结构：http://clip2net.com/s/3ON3F6n

There's a getAllBooks() method from BookDaoimpl:**

 @SuppressWarnings("unchecked")
    @Override
    public List<Book> getAllBooks(String bookName) {
        Session session = this.sessionFactory.getCurrentSession();
        String query = "SELECT * FROM books WHERE BOOK_TITLE like '%" + 
bookName + "%'";
        List<Object[]> bookObjects = session.createQuery(query).list();
        List<Book> books = new ArrayList<Book>();
        for (Object[] bookObject : bookObjects) {
            Book book = new Book();
            int id = (int) bookObject[0];
            String title = (String) bookObject[1];
            String description = (String) bookObject[2];
            String author = (String) bookObject[3];
            int isbn = (int) bookObject[4];
            int printYear = (int) bookObject[5];
            int readAlready = (int) bookObject[6];
            book.setId(id);
            book.setBookTitle(title);
            book.setDescription(description);
            book.setBookAuthor(author);
            book.setIsbn(isbn);
            book.setPrintYear(printYear);
            book.setReadAlready(readAlready);
            books.add(book);
        }
        System.out.println(books);

        return books;
    }

有一个MySQL数据库：http://clip2net.com/s/3ON4e7o和这个http://clip2net.com/s/3OPyIHL

My Book.class:
@Entity
@Table(name = "books")
public class Book {

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

    @Column(name = "BOOK_TITLE")
    private String bookTitle;

    @Column(name = "BOOK_AUTHOR")
    private String bookAuthor;

    @Column(name = "BOOK_DESCRIPTION")
    private String description;

    @Column(name = "ISBN")
    private int isbn;

    @Column(name = "PRINTYEAR")
    private int printYear;

    @Column(name = "READALREADY")
    private int readAlready;
......................................


**My mvc-dispatcher-servlet.xml:**
<!-- Specifying base package of the Components like Controller, Service, DAO -->
    <context:component-scan base-package="ru.maxim.bookmanager" />

    <!-- View Resolver -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/" />
        <property name="suffix" value=".jsp" />
    </bean>

    <!-- DataBase Information -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
          destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/bookmanager" />
        <property name="username" value="root" />
        <property name="password" value="root" />
    </bean>

    <!-- Hibernate & SessionFactory Bean definition-->
    <bean id="hibernate4AnnotatedSessionFactory"
          class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="annotatedClasses">
            <list>
                <value>ru.maxim.bookmanager.model.Book</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>

    <!-- BookDao & BookSession beans -->
    <bean id="bookDao" class="ru.maxim.bookmanager.dao.BookDaoImpl">
        <property name="sessionFactory" ref="hibernate4AnnotatedSessionFactory"></property>
    </bean>

    <bean id="bookService" class="ru.maxim.bookmanager.service.BookServiceImpl">
        <property name="bookDao" ref="bookDao"></property>
    </bean>

    <context:component-scan base-package="ru.maxim.bookmanager" />
    <tx:annotation-driven transaction-manager="transactionManager" />

    <!-- Transaction -->
    <bean id="transactionManager"
          class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="hibernate4AnnotatedSessionFactory" />
    </bean>
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven/>

如果我将查询更改为＆＃34; SELECT Book FROM Book b＆＃34;，我收到一个新的例外：请求处理失败;嵌套异常是java.lang.ClassCastException：ru.maxim.bookmanager.model.Book无法强制转换为[Ljava.lang.Object;

有什么问题？谢谢！

Answer 1

我认为你正在以错误的方式从数据库中获取数据。

您有两种方法可以解决该错误： -

使用Sql

Session session = this.sessionFactory.getCurrentSession();
String query = "SELECT * FROM books WHERE BOOK_TITLE like '%" + bookName + "%'";  
List<Object[]> bookObjects = session.createSQLQuery(query).list();
List<Book> books = new ArrayList<Book>(); 
//rest code snippet  will be same as your code snippet .

使用原生Hql

String book_title="book title name";
org.hibernate.Query que=session.createQuery("from Book where bookTitle  like ?");
que.setString(0,"%"+book_title+"%");
//rest will be same as your code snippet

这里使用Native HQL而不是表名（BOOK_TITLE）使用实体名称（BOOK）和就地名列（BOOK_TITLE）类变量名（bookTitle）将被使用

异常是org.hibernate.hql.internal.ast.QuerySyntaxException：书籍没有映射[FROM books ...

按标题搜索书籍：

1 个答案: