Question

我查看了相关问题，但仍未找到解决问题的答案。

这是我的项目结构：

 - src
  - java
   - HibernateDemo
     - HibernateTestApplication.java
     - HibernateUtil.java
   - Models
     - Users.java
   - res
     - hibernate.cfg.xml
     - Users.hbm.xml

这是我的hibernate.cfg.xml：

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://hibernate.sourceforge.net/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:3306/test</property>
        <property name="connection.username">root</property>
        <property name="connection.password">***</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Enable Hibernate's automatic session context management -->
        <!--<property name="current_session_context_class">thread</property>-->

        <!-- Disable the second-level cache  -->
        <!--<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>-->

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->
        <!--<property name="hbm2ddl.auto">update</property>-->

        <mapping resource="Users.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

这是我的Users.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="Models.Users" table="users">
        <meta attribute="class-description">
            This class contains the users detail.
        </meta>
        <id name="id" type="int" column="id">
            <generator class="native"/>
        </id>
        <property name="name" column="name" type="string"/>
        <property name="age" column="age" type="int"/>
    </class>
</hibernate-mapping>

这是我的Users.java：

package Models;

public class Users {
    private int id;
    private String name;
    private int age;

    public Users(){}

    public Users(String name, int age){
        this.name = name;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

这是我的HibernateUtil.java：

package HibernateDemo;

import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import java.io.File;

public class HibernateUtil {

    private static HibernateUtil instance = null;

    private static SessionFactory sessionFactory;
    private static StandardServiceRegistry serviceRegistry;

    private HibernateUtil(){
        String hibernatePropsFilePath = "E:\\java workspace\\study\\hibernate\\src\\main\\java\\res\\hibernate.cfg.xml";
        File hibernatePropsFile = new File(hibernatePropsFilePath);

        Configuration configuration = new Configuration();
        configuration.configure(hibernatePropsFile);
        serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
        sessionFactory = configuration.buildSessionFactory(serviceRegistry);
    }

    public static HibernateUtil getInstance(){
        if(instance == null){
            instance  = new HibernateUtil();
        }
        return instance;
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

}

这是我的HibernateTestApplication.java：

package HibernateDemo;

import Models.Users;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;

public class HibernateTestApplication {

    public static void main(String[] args) {
        HibernateTestApplication hibernateTestApplication = new HibernateTestApplication();
        int userId = hibernateTestApplication.addUser("Tom", 21);
        System.out.println(userId);
    }

    public int addUser(String name, int age){
        HibernateUtil hibernateUtil = HibernateUtil.getInstance();
        SessionFactory sessionFactory = hibernateUtil.getSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction tx = null;
        int userId = 0;

        try{
            tx = session.beginTransaction();
            Users user = new Users(name, age);
            userId = (Integer) session.save(user);
            tx.commit();
        }catch (HibernateException e) {
            if (tx!=null) tx.rollback();
            e.printStackTrace();
        }finally {
            session.close();
        }

        return userId;
    }
}

我希望你能耐心地阅读上面的代码，并找到我的代码中的真正问题，thx！

Answer 1

我没有在hibernate.cfg.xml。

中看到用户的类映射

Hibernate配置文件必须定义实体类：

<mapping class="Models.Users"/>

Answer 2

当您提供映射资源时，请以此格式提供绝对路径：

<mapping resource="res/Users.hbm.xml" /＆GT;

如果是通过类名映射，（当它将类解析为包名时） <mapping class="Models.Users" /＆GT;

如上所述不起作用，请尝试构建会话工厂：

protected static SessionFactory buildSessionFactory() {
    try {

        SessionFactory sessionFactory = new Configuration()
                .configure("/res/hibernate.cfg.xml")
                .addResource("res/Users.hbm.xml")
                .buildSessionFactory();

        return sessionFactory;

    } catch (Throwable ex) {
        System.err.println("SessionFactory creation failed" + ex);
    }
}

查看此加载是否正确。这使用当前类路径来解析，而不是从文件系统加载hbm文件。

org.hibernate.MappingException：未知实体：Models.Users

2 个答案: