`未知實體`在休眠異常

我正在學習hibernate，我無法弄清楚爲什麼會出現這個錯誤。我嘗試搜索，但我找不到幫助我的解決方案。我想知道爲什麼我得到這個錯誤。`未知實體`在休眠異常

Exception in thread "main" org.hibernate.MappingException: Unknown entity: com.simpleprogrammer.User 
at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:776) 
at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1451) 
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:100) 
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:678) 
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:670) 
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:665) 
at Program.main(Program.java:23)

請幫我已經浪費了太多的時間調試此。這裏是我的簡單程序，

Program.java

import org.hibernate.Session; 
import com.simpleprogrammer.HibernateUtilities; 
import com.simpleprogrammer.User; 

public class Program { 

/** 
* @param args 
* @throws ClassNotFoundException 
* @throws SQLException 
*/ 
public static void main(String[] args) { 
    // TODO Auto-generated method stub 
    System.out.println("Hello World"); 
    Session session = HibernateUtilities.getSessionFactory().openSession(); 

    session.beginTransaction(); 

    User user = new User(); 
    user.setName("Deepak"); 
    user.setTotal(130); 
    user.setGoal(150); 
    session.save(user); 

    session.getTransaction().commit(); 

    session.close(); 

} 


}

HibernateUtilities.java

package com.simpleprogrammer; 
import org.hibernate.HibernateException; 

import org.hibernate.SessionFactory; 

import org.hibernate.boot.registry.StandardServiceRegistryBuilder; 

import org.hibernate.cfg.Configuration; 

import org.hibernate.service.ServiceRegistry; 



public class HibernateUtilities { 

public static SessionFactory sessionFactory; 
public static ServiceRegistry serviceRegistry; 

static{ 
    try{ 
     Configuration configuation = new Configuration().configure(); 

     serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuation.getProperties()).build(); 

     sessionFactory = configuation.buildSessionFactory(serviceRegistry); 

    }catch(HibernateException e){ 
     System.out.println("Error while creating Session Factory."); 
     e.printStackTrace(); 
    } 
} 

public static SessionFactory getSessionFactory(){ 
    return sessionFactory; 
}

}

User.java

package com.simpleprogrammer; 

public class User { 

private int id; 
private String name; 
private int total; 
private int goal; 
public int getId() { 
    return id; 
} 
public void setId(int id) { 
    this.id = 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; 
} 


}

用戶。 hbm.xml中

<?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 Oct 28, 2015 8:05:49 PM by Hibernate Tools 3.4.0.CR1 --> 
<hibernate-mapping> 
<class name="com.simpleprogrammer.User" table="users"> 
    <id name="id" type="int"> 
     <column name="id" /> 
     <generator class="identity" /> 
    </id> 
    <property name="name" type="java.lang.String"> 
     <column name="name" /> 
    </property> 
    <property name="total" type="int"> 
     <column name="total" /> 
    </property> 
    <property name="goal" type="int"> 
     <column name="goal" /> 
    </property> 
</class> 
</hibernate-mapping>

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> 
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> 
    <property name="hibernate.connection.password">admin</property> 
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306</property> 
    <property name="hibernate.connection.username">root</property> 
    <property name="hibernate.default_schema">protein_tracker</property> 
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> 
    <mapping resource="com/simpleprogrammer/User.hbm.xml" /> 
</session-factory>