java - Hibernate 找不到书来创建表

Question

在处理来自互联网的代码时，我收到错误

Exception in thread "main" org.hibernate.MappingException: Unknown entity: Book

Book.java

public class Book {

    private String isbn;
    private String title;
    private String author;

    public Book() {
    }
//getters and setters

保存数据:

            Configuration cfg = new Configuration().configure("hibernate.cfg.xml");

            SessionFactory sf = cfg.buildSessionFactory(new StandardServiceRegistryBuilder().applySettings(
                    cfg.getProperties()).build());


            Session session = sf.openSession();

            session.beginTransaction();
            Book book = new Book("12345767", "Welcome to hibernate","Test");
            session.save(book);
            session.getTransaction().commit();
            System.out.println("data saved");
            System.out.println("<------>");
            session.close();
            sf.close();

        }
    }

Hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration SYSTEM 
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- Database connection Settings -->
        <property name="connection.driver_Class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/test</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
        <!-- JDBC connection pool -->
        <property name="connection.pool_size">1</property>
        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <!-- Disable the second level cache -->
        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>
        <property name="show_sql">true</property>
        <property name="hbm2ddl.auto">create</property>
        <mapping resource="Book.hbm.xml" />
    </session-factory>
</hibernate-configuration>

Book.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="Book" table="books">
        <id name="isbn">
            <generator class="auto" />
        </id>
        <property name="title" />
        <property name="author" />
    </class>
</hibernate-mapping>

我无法解决此错误，因为我已在映射文件中提供了所有内容。有什么方法可以解决此问题吗？

Answer 1

您的错误日志清楚地表明 Hibernate 无法找到 jdbc:mysql 的合适驱动程序。

<强>1。您是否在项目中添加了 MySQL JDBC 驱动程序库？

<强>2。您尚未在 hibernate.cfg.xml 文件中的以下行提供端口号:-

<property name="connection.url">jdbc:mysql://localhost/test</property>

将此行替换为

<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>