5.0以上使用这个

hibernate5+用这个方式获取ServiceRegistry、SessionFactory：

ServiceRegistry sr = new StandardServiceRegistryBuilder().configure().build();
sessionFactory = new MetadataSources(sr).buildMetadata().buildSessionFactory();

我也碰到了和你一模一样的问题，解决了

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

刚开始我看到这句话，首先肯定是hibernate的错误 mapping映射错误

我还以为是hibernate的cfg.xml里的<mapping>标签里的映射文件路径写错了，导致找不到持久化类。但是检查确认了老半天，发现文件路径是对的，很崩溃。

后来发现我导入的hibernate框架是我自己从官网上下载的hibernate 5.2,不是老师讲课用的hibernate4.3。

然后重新导了一下老师讲课用的hibernate4.3,然后错误就没了。

你是不是用的不是老师讲课用的hibernate4.3啊，视频下方的课程资源下一下。不要用上一节课的hibernate4.2.4,也不要从官网上下最新的。版本不一样 API可能不一样。

package com.test.entity;

import java.io.Serializable;

import java.util.HashSet;

import java.util.Set;

public class Grade implements Serializable {

private int gid;

private String gname;

private String gdesc;

//在一方定义一个多方的集合

private Set<Student> students =new HashSet<Student>();

public Grade() {

//super();

}

public Grade(int gid, String gname, String gdesc, Set<Student> students) {

//super();

this.gid = gid;

this.gname = gname;

this.gdesc = gdesc;

this.students = students;

}

public int getGid() {

return gid;

}

public void setGid(int gid) {

this.gid = gid;

}

public String getGname() {

return gname;

}

public void setGname(String gname) {

this.gname = gname;

}

public String getGdesc() {

return gdesc;

}

public void setGdesc(String gdesc) {

this.gdesc = gdesc;

}

public Set<Student> getStudents() {

return students;

}

public void setStudents(Set<Student> students) {

this.students = students;

}

public Grade(String gname, String gdesc) {

//super();

this.gname = gname;

this.gdesc = gdesc;

}

package com.test.entity;

import java.io.Serializable;

import java.util.HashSet;

import java.util.Set;

public class Grade implements Serializable {

private int gid;

private String gname;

private String gdesc;

//在一方定义一个多方的集合

private Set<Student> students =new HashSet<Student>();

public Grade() {

//super();

}

public Grade(int gid, String gname, String gdesc, Set<Student> students) {

//super();

this.gid = gid;

this.gname = gname;

this.gdesc = gdesc;

this.students = students;

}

public int getGid() {

return gid;

}

public void setGid(int gid) {

this.gid = gid;

}

public String getGname() {

return gname;

}

public void setGname(String gname) {

this.gname = gname;

}

public String getGdesc() {

return gdesc;

}

public void setGdesc(String gdesc) {

this.gdesc = gdesc;

}

public Set<Student> getStudents() {

return students;

}

public void setStudents(Set<Student> students) {

this.students = students;

}

public Grade(String gname, String gdesc) {

//super();

this.gname = gname;

this.gdesc = gdesc;

}

}

}

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<!-- Mapping file autogenerated by MyEclipse Persistence Tools -->

<hibernate-mapping>

<class name="com.test.entity.Grade" table="grade" catalog="swh1">

<id name="gid" type="java.lang.Integer">

<column name="gid" />

<generator class="native" />

</id>

<property name="gname" type="java.lang.String">

<column name="gname" length="20" not-null="true" />

</property>

<property name="gdesc" type="java.lang.String">

<column name="gdesc" length="50" />

</property>

<set name="students" table="student">

<key>

<column name="gid" />

</key>

<one-to-many class="com.test.entity.Student" />

</set>

</class>

</hibernate-mapping>

<?xml version='1.0' encoding='utf-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

          "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:3306/swh1?useUnicode=true&amp;characterEncoding=UTF-8</property>

    -->

    <property name="connection.url">

    <![CDATA[

    jdbc:mysql://localhost:3306/swh1?useUnicode=true&characterEncoding=UTF-8

    ]]>

    </property>

    <property name="connection.username">root</property>

    <property name="connection.password">root</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.internal.NoCacheProvider</property>

-->

    <!-- Echo all executed SQL to stdout -->

    <property name="show_sql">true</property>

    <!-- Drop and re-create the database schema on startup -->

    <property name="hbm2ddl.auto">update</property>

    <!-- 指定映射文件的路径 -->

    <mapping resource="com/test/entity/Grade.hbm.xml"/>

    <mapping resource="com/test/entity/Student.hbm.xml"/>

  </session-factory>

</hibernate-configuration>

代码呢兄弟