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

Question

考虑层次结构：

以及以下类和 xml：

HibernateUtil.java

 package annotations;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

/**
 *
 * @author X3
 *
 */
public class HibernateUtil {

    private static final SessionFactory sessionFactory = buildSessionFactory();
    private static final String HIBERNATE_CFG = "hibernateAnnotations.cfg.xml";

    private static SessionFactory buildSessionFactory()
    {
        Configuration cfg = new Configuration().addResource(HIBERNATE_CFG).configure();
        ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().
                applySettings(cfg.getProperties()).buildServiceRegistry();
        SessionFactory sessionFactory = cfg.buildSessionFactory(serviceRegistry);
        return sessionFactory;
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

用户.java

 package annotations;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import java.sql.Timestamp;

@Entity
@Table(name = "Users")
public class Users {

    @Id
    @GeneratedValue
    @Column(name = "USER_ID")
    private long userID;

    @Column(name = "USERNAME", nullable = false, length = 100)
    private String username;

    @Column(name = "MessageTimeDate", nullable = false)
    private java.sql.Timestamp datetime;

    @Column(name = "UserMessage", nullable = false)
    private String message;

    public Users(String username , String message)
    {
        java.util.Date date = new java.util.Date();
        this.datetime = new Timestamp(date.getTime());

        this.username = username;
        this.message = message;
    }

    public long getUserID() {
        return userID;
    }

    public void setUserID(long userID) {
        this.userID = userID;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public java.sql.Timestamp getDatetime() {
        return datetime;
    }

    public void setDatetime(java.sql.Timestamp datetime) {
        this.datetime = datetime;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

}

主.java

 package annotations;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

public class Main {

    public static void main(String[] args) {

        try
        {
               SessionFactory sf = HibernateUtil.getSessionFactory();
               Session session = sf.openSession();
               session.beginTransaction();

               Users user1 = new Users("Jack" , "Hello");
               session.save(user1);
               session.getTransaction().commit();
               session.close();
        }

        catch (Exception e)
        {
            System.out.println(e.toString());
            e.getStackTrace();
        }

    }
}

和 hibernateAnnotations.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>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/CHAT_DB</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
        <property name="connection.pool_size">1</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="current_session_context_class">thread</property>
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
        <property name="show_sql">true</property>
        <property name="hbm2ddl.auto">create</property>
        <mapping class="annotations.Users"></mapping>
    </session-factory>
</hibernate-configuration>

当我运行 main() 时，输出窗口中出现以下错误：

 org.hibernate.MappingException: Unknown entity: annotations.Users

但是实体 Users 在 annotations 包中，所以有什么问题吗？

原文由 JAN 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

Hibernate 配置文件必须定义实体类：

 <mapping class="annotations.Users"/>

或者您必须显式地将类添加到配置中使用

configuration.addClass(annotations.Users.class)
// Read mappings as a application resourceName
 // addResource is for add hbml.xml files in case of declarative approach
configuration.addResource("myFile.hbm.xml");  // not hibernateAnnotations.cfg.xml

原文由 Asif Bhutto 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

当我试图重写我的示例（来自 tutorialspoint）以使用注释时，我遇到了同样的异常。这对我有帮助（addAnnotatedClass()）：

 Configuration cfg=new Configuration();
cfg.addAnnotatedClass(com.tutorialspoint.hibernate.entity.Employee.class);
cfg.configure();

原文由 user5728489 发布，翻译遵循 CC BY-SA 3.0 许可协议