为什么在Hibernate 5.2中saveOrUpdate的行为不符合记录

Question

在Hibernate 5.2中，org.hibernate.Session.saveOrUpdate()不会为分离的对象执行update，而是执行save。

使用Hibernate 3.6时，它按预期工作。

这些是重现问题的文件：

1. 实体Person.java：

   package model;
   
   import javax.persistence.*;
   
   @Entity
   public class Person
   {
       @Id
       @GeneratedValue
       private Long id;
       @Column(unique = true)
       private String name;
       private Integer age;
   
       public void setName(String name)
       {
           this.name = name;
       }
   
       public void setAge(Integer age)
       {
           this.age = age;
       }
   }

2. DAO接口HibernateTestDao.java：

   package model;
   
   public interface HibernateTestDao
   {
       void test();
   }

3. 和DAO实施HibernateTestDaoImpl.java：

   package model;
   
   import org.hibernate.SessionFactory;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.stereotype.Repository;
   import org.springframework.transaction.annotation.Transactional;
   
   @Transactional(readOnly = true)
   @Repository
   public class HibernateTestDaoImpl implements HibernateTestDao
   {
       @Autowired
       private SessionFactory sessionFactory;
   
       @Transactional(readOnly = false)
       @Override
       public void test()
       {
           Person person = new Person();
           person.setName("Joe");
           person.setAge(10);
   
           Long id = (Long)sessionFactory.getCurrentSession().save(person);
   
           sessionFactory.getCurrentSession().flush();
   
           person = sessionFactory.getCurrentSession().get(Person.class, id);
   
           sessionFactory.getCurrentSession().clear();
   
           person.setAge(11);
   
           sessionFactory.getCurrentSession().saveOrUpdate(person);
           sessionFactory.getCurrentSession().flush();
   
           throw new RuntimeException();
       }
   
   }

4. 主要类HibernateTest.java：

   package test;
   
   import org.springframework.context.support.ClassPathXmlApplicationContext;
   
   import model.HibernateTestDao;
   
   public class HibernateTest
   {
       public static void main(String[] args)
       {
           ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:/applicationContext.xml");
   
           HibernateTestDao dao = applicationContext.getBean(HibernateTestDao.class);
   
           dao.test();;
   
           applicationContext.close();
       }
   }

5. Spring配置文件applicationContext.xml：

   <?xml version="1.0" encoding="UTF-8"?>
   
   <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:context="http://www.springframework.org/schema/context"
     xmlns:util="http://www.springframework.org/schema/util"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:tx="http://www.springframework.org/schema/tx"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
           http://www.springframework.org/schema/tx
           http://www.springframework.org/schema/tx/spring-tx-4.3.xsd
           http://www.springframework.org/schema/util
           http://www.springframework.org/schema/util/spring-util-4.3.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-4.3.xsd">
   
       <context:component-scan base-package="model"/>
   
       <bean id="dataSource"  class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">
           <property name="driverClassName" value="com.mysql.jdbc.Driver" />
           <property name="url" value="jdbc:mysql://localhost:3306/hibernatetest" />
           <property name="username" value="hibernatetest" />
           <property name="password" value="hibernatetest" />
       </bean>
   
       <bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
           <property name="packagesToScan">
               <list>
                   <value>model</value>
               </list>
           </property>
           <property name="hibernateProperties">
               <props>
                   <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>
                   <prop key="hibernate.id.new_generator_mappings">false</prop>
                   <prop key="hibernate.show_sql">true</prop>
                   <prop key="hibernate.generate_statistics">false</prop>
                   <prop key="hibernate.max_fetch_depth">3</prop>
               </props>
           </property>
           <property name="dataSource">
               <ref bean="dataSource"/>
           </property>
       </bean>
   
       <tx:annotation-driven/>
   
       <bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
           <property name="sessionFactory" ref="sessionFactory"/>
       </bean>
   
   </beans>

6. 最后是pom.xml文件：

   <project        
     xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
       http://maven.apache.org/xsd/maven-4.0.0.xsd">
   
     <modelVersion>4.0.0</modelVersion>
     <groupId>ProvaHibernate</groupId>
     <artifactId>ProvaHibernate</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <properties>
         <hibernate.version>5.2.12.Final</hibernate.version>
         <spring.version>4.3.12.RELEASE</spring.version>
     </properties>
     <build>
       <sourceDirectory>src</sourceDirectory>
       <plugins>
         <plugin>
           <artifactId>maven-compiler-plugin</artifactId>
           <version>3.7.0</version>
           <configuration>
             <source>1.8</source>
             <target>1.8</target>
           </configuration>
         </plugin>
       </plugins>
     </build>
     <dependencies>
         <dependency>
             <groupId>org.hibernate</groupId>
             <artifactId>hibernate-core</artifactId>
             <version>${hibernate.version}</version>
         </dependency>
         <dependency>
             <groupId>org.hibernate</groupId>
             <artifactId>hibernate-validator</artifactId>
             <version>5.3.4.Final</version>
         </dependency>
           <dependency>
                   <groupId>mysql</groupId>
                   <artifactId>mysql-connector-java</artifactId>
                   <version>5.1.45</version>
           </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-beans</artifactId>
             <version>${spring.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-context</artifactId>
             <version>${spring.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-orm</artifactId>
             <version>${spring.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-tx</artifactId>
             <version>${spring.version}</version>
         </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-dbcp2</artifactId>
             <version>2.1.1</version>
         </dependency>
      </dependencies>
   </project>

执行时控制台显示：

    Hibernate: insert into Person (age, name) values (?, ?)
    Hibernate: insert into Person (age, name) values (?, ?)
    Dec 13, 2017 6:26:47 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
    WARN: SQL Error: 1062, SQLState: 23000
    Dec 13, 2017 6:26:47 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
    ERROR: Duplicate entry 'Joe' for key 'person_un'
    Exception in thread "main"
    org.hibernate.exception.ConstraintViolationException: could not execute statement
    ...
    Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException:
    Duplicate entry 'Joe' for key 'person_un'
    ...

如果我删除了sessionFactory.getCurrentSession().clear();中的HibernateTestDaoImpl.javastatement，让Person对象进入会话，那么控制台会显示：

    Hibernate: insert into Person (age, name) values (?, ?)
    Hibernate: update Person set age=?, name=? where id=?

Hibernate documentation声称saveOrUpdate将一个独立的对象重新附加到会话中：

这是一个Hibernate 5.2错误，我错过了一些东西。

Answer 1

它不是Hibernate的错误。

在这个answer之后，我在integrate的方法JpaAnnotationsIntegrator上添加了一个句子，引发了这个问题。增加的句子是：

eventListenerRegistry.prependListeners(EventType.SAVE_UPDATE, new JpaSaveEventListener(callbackRegistry));

更新：我忘了说我没有使用任何监听器，只是安装服务。我无法理解为什么这会在saveOrUpdate中引发这种行为。如果我通过prependListeners改变appendListeners，那么事情就会正常进行。