Hibernate Mapping Exception : Unknown Entity

Question

I am mapping a simple POJO to a database table in SQL server using xml file mapping. I am getting Hibernate Mapping Exception: Unknown Entity
These are my code files:
Entry point class:

public class Program {

    public static void main(String[] args) {
        System.out.println("Helo World");

        Session session = HibernateUtilities.getSessionFactory().openSession();
        session.beginTransaction();

        User user = new User();
        user.setId(1);
        user.setName("Ajay");
        user.setGoal(100);
        user.setTotal(0);

        session.save(user);

        session.getTransaction().commit();
        session.close();
        HibernateUtilities.getSessionFactory().close();
        System.out.println("session closed");
    }

}

this is HibernateUtilities class:

public class HibernateUtilities {
        private static SessionFactory sessionFactory;
        private static ServiceRegistry serviceRegistry;
        static {
            try {
                Configuration configuration = new Configuration().configure();
                serviceRegistry = new StandardServiceRegistryBuilder()
                        .applySettings(configuration.getProperties()).build();
                sessionFactory = configuration.buildSessionFactory(serviceRegistry);
            } catch (HibernateException e) {
                System.out.println(e);
            }
        }

        public static SessionFactory getSessionFactory(){
            return sessionFactory;
        }

}

this is POJO User:

public class User {
    private int id;
    private String name;
    private int total;
    private int goal;

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

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

    public int getTotal() {
        return total;
    }

    public void setTotal(int total) {
        this.total = total;
    }

    public int getGoal() {
        return goal;
    }

    public void setGoal(int goal) {
        this.goal = goal;
    }

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

This is Mapping file:

<?xml version="1.0"?>
    <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
                                       "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
    <!-- Generated Sep 14, 2016 11:58:02 AM by Hibernate Tools 3.4.0.CR1 -->
    <hibernate-mapping package="com.example.hibernate">
     <class entity-name="User" name="com.example.hibernate.User" table="USERS">
      <id name="id" type="int">
       <column name="ID"/>
       <generator class="increment"/>
      </id>
      <property generated="never" lazy="false" name="name" type="java.lang.String">
       <column name="NAME"/>
      </property>
      <property generated="never" lazy="false" name="total" type="int">
       <column name="TOTAL"/>
      </property>
      <property generated="never" lazy="false" name="goal" type="int">
       <column name="GOAL"/>
      </property>
     </class>
    </hibernate-mapping>

this is configuration file:

<?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 name="">
      <property name="hibernate.connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
      <property name="hibernate.connection.password">ajay1994</property>
      <property name="hibernate.connection.url">jdbc:sqlserver://localhost:1433;databaseName=protein_tracker</property>
      <property name="hibernate.connection.username">test</property>
      <property name="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</property>
      <mapping class="com.example.hibernate.User" resource="com/example/hibernate/User.hbm.xml"/>
     </session-factory>
    </hibernate-configuration>

Stack Trace for Error:

Helo World
Sep 14, 2016 2:58:58 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {5.2.2.Final}
Sep 14, 2016 2:58:58 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
Sep 14, 2016 2:58:58 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
Sep 14, 2016 2:58:58 PM org.hibernate.boot.jaxb.internal.stax.LocalXmlResourceResolver resolveEntity
WARN: HHH90000012: Recognized obsolete hibernate namespace http://hibernate.sourceforge.net/hibernate-configuration. Use namespace http://www.hibernate.org/dtd/hibernate-configuration instead.  Support for obsolete DTD/XSD namespaces may be removed at any time.
Sep 14, 2016 2:58:58 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
Sep 14, 2016 2:58:58 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH10001002: Using Hibernate built-in connection pool (not for production use!)
Sep 14, 2016 2:58:58 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001005: using driver [com.microsoft.sqlserver.jdbc.SQLServerDriver] at URL [jdbc:sqlserver://localhost:1433;databaseName=protein_tracker]
Sep 14, 2016 2:58:58 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001001: Connection properties: {user=test, password=****}
Sep 14, 2016 2:58:58 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001003: Autocommit mode: false
Sep 14, 2016 2:58:58 PM org.hibernate.engine.jdbc.connections.internal.PooledConnections <init>
INFO: HHH000115: Hibernate connection pool size: 20 (min=1)
Sep 14, 2016 2:58:58 PM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.SQLServerDialect
Exception in thread "main" org.hibernate.MappingException: Unknown entity: com.example.hibernate.User
    at org.hibernate.metamodel.internal.MetamodelImpl.entityPersister(MetamodelImpl.java:620)
    at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1604)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:104)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:673)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:665)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:660)
    at com.example.hibernate.Program.main(Program.java:18)

Answer 1

open hibernate.cfg.xml file. press ctrl and hold it and click on mapping class " com.example.hibernate.User " check whether you are navigated to User class or not.

Answer 2

For anyone refereing this question today.Looks like he is using xml for mapping and in cfg.xml he used class and resource.If you are using hbm.xml for mapping cfg.xml should contain

  <mapping resource="com/example/hibernate/User.hbm.xml"/>

and if you are using annotation for mapping cfg.xml should contain the below mappping

  <mapping class="com.example.hibernate.User"/>

and you cannot use both in mapping.

Answer 3

For me it was the fact that at some point hibernate started using the annotations from jakarta.persistence.* as opposed to java.persistence.*

WOOHOO HOPE IT DOESN'T TAKE HOURS OF HEAD POUNDING TO FIGURE THAT OUT!