今天看视频教程学习了一下Hibernate,按照视频教程中的代码写,老师测试通不过,老报错,苦苦找不到原因,最终经过一个下午一个晚上的时间找出了原因,遂记录一下,希望帮助到有需要的人。
先说下报错:
org.hibernate.MappingException: Unknown entity
这句报错的原因是映射没有成功,查看Bean和Hibernate的主配置文件和映射配置文件如下:
Students.java
package cn.codekong.entity;
/**
* 学生类
* @author szh
*
*/
public class Students{
private int sid;
private String sname;
private String gender;
private String address;
public Students() {
}
public Students(int sid, String sname, String gender, String address) {
super();
this.sid = sid;
this.sname = sname;
this.gender = gender;
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 String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", address=" + address + "]";
}
}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
hibernate.cfg.xml
<?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">root</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql:///hibernate?useUnicode=true&characterEncoding=UTF-8</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="hbm2ddl.auto">create</property>
<mapping resource="cn/codekong/entity/Students.hbm.xml"/>
</session-factory>
</hibernate-configuration>
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
Students.hbm.xml
<?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 2017-4-2 18:05:47 by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
<class name="cn.codekong.entity.Students" table="STUDENTS">
<id name="sid" type="int">
<column name="SID" />
<generator class="assigned" />
</id>
<property name="sname" type="java.lang.String">
<column name="SNAME" />
</property>
<property name="gender" type="java.lang.String">
<column name="GENDER" />
</property>
<property name="address" type="java.lang.String">
<column name="ADDRESS" />
</property>
</class>
</hibernate-mapping>
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
StudentsTest.java
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 cn.codekong.entity.Students;
public class StudentsTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void init() {
//创建配置对象
Configuration configuration = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
//创建会话工厂对象
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
//会话对象
session = sessionFactory.openSession();
//开启事物
transaction = session.beginTransaction();
}
@After
public void destory() {
//提交事物
transaction.commit();
//关闭会话
session.close();
//关闭会话工厂
sessionFactory.close();
}
@Test
public void testSaveStudents() {
//生成学生对象
Students student = new Students(1, "张三丰", "男", "武当山");
System.out.println(student);
session.save(student);
System.out.println(session);
}
}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
上面的代码看其实确实是对的,但是就是测试跑不通,最终发现是版本问题 ,对,版本问题,视频里面是Hibernate3.x,而我使用的是Hibernate5.x,所以代码有变化。
说明一下,上面的代码在Hibernate5.x以下是可以运行的,但是在Hibernate5.x以后,必须写成如下的形式:
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.service.ServiceRegistry;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import cn.codekong.entity.Students;
public class StudentsTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void init() {
//创建服务注册对象
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
//创建会话工厂对象
sessionFactory = new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
//会话对象
session = sessionFactory.openSession();
//开启事物
transaction = session.beginTransaction();
}
@After
public void destory() {
//提交事物
transaction.commit();
//关闭会话
session.close();
//关闭会话工厂
sessionFactory.close();
}
@Test
public void testSaveStudents() {
//生成学生对象
Students student = new Students(1, "张三丰", "男", "武当山");
System.out.println(student);
session.save(student);
System.out.println(session);
}
}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
主要的变化就两句代码,便可以解决问题,希望可以帮助到有需要的人。
原文转自:https://blog.csdn.net/bingjianit/article/details/68954250
今天看视频教程学习了一下Hibernate,按照视频教程中的代码写,老师测试通不过,老报错,苦苦找不到原因,最终经过一个下午一个晚上的时间找出了原因,遂记录一下,希望帮助到有需要的人。