出错啦，org.hibernate.MappingException: Unknown entity: lin.Students

package lin;

import java.util.Date;

import javax.persistence.Entity;

import javax.persistence.Id;

import javax.persistence.Table;

//学生类

@Entity

@Table(name="students_info")

public class Students {

// 1.公有的类

// 2、提供公有的不带参数的默认的构造方法

// 3.属性私有

// 4.属性setter，getter封装

@Id

private int sid; // 学号

private String sname; // 姓名

private String gender; // 性别

private Date birthday; // 出生日期

private String address;// 地址

public Students() {

}

public Students(int sid, String sname, String gender, Date birthday, String address) {

// super();

this.sid = sid;

this.sname = sname;

this.gender = gender;

this.birthday = birthday;

this.address = address;

}

public int getSid() {

return sid;

}

public void setSid(int sid) {

this.sid = sid;

}

public String getSname() {

return sname;

}

public void setSname(String sname) {

this.sname = sname;

}

public String getGender() {

return gender;

}

public void setGender(String gender) {

this.gender = gender;

}

public Date getBirthday() {

return birthday;

}

public void setBirthday(Date birthday) {

this.birthday = birthday;

}

public String getAddress() {

return address;

}

public void setAddress(String address) {

this.address = address;

}

@Override

public String toString() {

return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday

+ ", address=" + address + "]";

}

}

<?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>

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

  <property name="connection.password">123456</property>

  <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

  <property name="connection.url">jdbc:mysql://localhost:3306/hibernate?useUnicode=true&amp;characterEncoding=UTF-8</property>

  <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

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

  <property name="hibernate.format_sql">true</property>

  <property name="hdm2ddl.auto">create</property>

  <property name="hibernate.current_session_context_class">thread</property>

  <mapping class="lin.Students"/>

 </session-factory>

</hibernate-configuration>

import java.util.Date;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

import org.hibernate.cfg.Configuration;

import org.hibernate.service.ServiceRegistry;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

import lin.Students;

//测试类

public class StudentsTest{

private SessionFactory sessionFactory;

private Session session;

private Transaction transaction;

@Before

public void init(){

//创建配置对象

//不带参数的configure（）方法默认加载hibernate.cfg.xml文件

//如果传入abc.xml作为参数，则不再加载hibernate.cfg.xml,改为加载abc.xml

Configuration config = new Configuration().configure();

//创建服务注册对象

ServiceRegistry serviceRegistry=new StandardServiceRegistryBuilder().applySettings(config.getProperties()).build();

//创建会话工厂对象

sessionFactory = config.buildSessionFactory(serviceRegistry);

//创建会话对象

session=sessionFactory.openSession();

//开启事务

transaction=session.beginTransaction();

}

@After

public void destroy(){

transaction.commit(); //提交事务

session.close(); // 关闭会话

sessionFactory.close();//关闭会话工厂

}

@Test

public void testSaveStudents()

{

//生成学生对象

Students s =new Students(1,"张三丰","男",new Date(),"武当山");

session.save(s); //保存对象进数据库

}

}

运行结果：

org.hibernate.MappingException: Unknown entity: lin.Students

at org.hibernate.metamodel.internal.MetamodelImpl.entityPersister(MetamodelImpl.java:620)

at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1596)

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:668)

at org.hibernate.internal.SessionImpl.save(SessionImpl.java:660)

at org.hibernate.internal.SessionImpl.save(SessionImpl.java:655)

at StudentsTest.testSaveStudents(StudentsTest.java:56)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)

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:325)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)

at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)