1. hibernate entity not found: (carefully check if your package is imported wrong)

org.hibernate.MappingException: Unknown entity: com.huangliusong.entity.Person
at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1192)
at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1403)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:117)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:204)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:189)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:757)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:749)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:745)
at com.huangliusong.test.Test_joined.test1(Test_joined.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

2. Solution.

Check out your own test code

package com.huangliusong.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.huangliusong.entity.Person;
import com.huangliusong.entity.Student;

public class Test_joined {
	// Create a session factory
	SessionFactory sessionFactory = null;
	// Create a session
	Session session = null;
	// Create a transaction
	Transaction transaction = null;

	@Before
	public void init() {
		// 1. Create the configuration object
		Configuration configuration = new Configuration().configure();
		// 2. Create the service registration object
		ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
				.applySettings(configuration.getProperties())
				.buildServiceRegistry();
		sessionFactory=configuration.buildSessionFactory(serviceRegistry);
		session=sessionFactory.openSession();
		transaction=session.beginTransaction();
	}
	@After
	public void destory(){
		transaction.commit();
		session.close();
		sessionFactory.close();
	}
	@Test
	public void test1(){
		Person person=new Person();
		person.setAge(111);
		person.setName("huang");
		
		Student student=new Student();
		student.setAge(1);
		student.setName("xiao wu");
		student.setSchool("GaungXi School");
		
		session.save(person);
		session.save(student);
	}
}

Found my own test code guide package imported by.

import com.huangliusong.entity.Person;
import com.huangliusong.entity.Student;

Modify:

import com.huangliusong.joined.Person;
import com.huangliusong.joined.Student;

Complete the test code as follows”

package com.huangliusong.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.huangliusong.joined.Person;
import com.huangliusong.joined.Student;


public class Test_joined {
	// Create a session factory
	SessionFactory sessionFactory = null;
	// Create a session
	Session session = null;
	// Create a transaction
	Transaction transaction = null;

	@Before
	public void init() {
		// 1.Create the configuration object
		Configuration configuration = new Configuration().configure();
		// 2. Create the service registration object
		ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
				.applySettings(configuration.getProperties())
				.buildServiceRegistry();
		sessionFactory=configuration.buildSessionFactory(serviceRegistry);
		session=sessionFactory.openSession();
		transaction=session.beginTransaction();
	}
	@After
	public void destory(){
		transaction.commit();
		session.close();
		sessionFactory.close();
	}
	@Test
	public void test1(){
		Person person=new Person();
		person.setAge(111);
		person.setName("huang");
		
		Student student=new Student();
		student.setAge(1);
		student.setName("xiao wu");
		student.setSchool("GuangXi School");
		
		session.save(person);
		session.save(student);
	}
}

success!