1、環境準備

spring boot版本：2.3.1.RELEASE

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網上搜索spring boot 2.x hibernate配置，很多都是(yes)jpa例子
從關系上來(Come)說應該是(yes)spring data jpa-》hibernate-》jpa，jpa是(yes)注解規範，jpa是(yes)基于(At)hibernate幫我(I)們(them)實現一(one)些通用(use)的(of)操作(do)。
因爲(for)需要(want)把舊的(of)項目（spring mvc + spring + hibernat 3.6.5，前後端分離）升級spring boot 2.x，這(this)裏隻讨論hibernate的(of)配置，畢竟除了(Got it)hibernate的(of)部分需要(want)升級，其他(he)的(of)部分大(big)部分都可以(by)通用(use)。

2、sessionFactory

hibernate别的(of)不(No)需要(want)多說，隻需要(want)設置sessionFactory就可以(by)了(Got it)。

spring boot可以(by)直接從EntityManagerFactory獲取sessionFactory.

下面是(yes)修改SimpleHibernateDao的(of)代碼，SimpleHibernateDao是(yes)舊項目裏的(of)封裝了(Got it)常用(use)方法的(of)基類

@Autowired
private EntityManagerFactory entityManagerFactory;
/**
 * 取得sessionFactory.
 */
public SessionFactory getSessionFactory() {
    return entityManagerFactory.unwrap(SessionFactory.class);
}
/**
 * 取得當前Session.
 */
protected Session getSession() {
    return getSessionFactory().getCurrentSession();
}

獲取session的(of)2種方式：
1、getCurrentSession()會自動關閉session，但是(yes)要(want)配置current_session_context_class，并且需要(want)使用(use)事務
2、openSession()這(this)種方式需要(want)手動關閉session

3、步驟三

前面配置完，測試報no transaction is in progress錯誤
解決方法1:代碼配置

spring.jpa.database=MYSQL
spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=none
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.properties.hibernate.current_session_context_class=org.springframework.orm.hibernate5.SpringSessionContext
spring.jpa.properties.hibernate.show-sql=true
spring.jpa.properties.hibernate.cache.use_second_level_cache=false
spring.jpa.properties.hibernate.cache.use_query_cache=false

@Configuration
public class HibernateConfig {
    @Autowired
    private Environment environment;
   @Autowired
    private DataSource dataSource;
    @Bean
    public LocalSessionFactoryBean sessionFactoryBean() {
        LocalSessionFactoryBean sessionFactoryBean = new LocalSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setPackagesToScan("com.qizhan100");//dao和(and)entity的(of)公共包
        sessionFactoryBean.setHibernateProperties(hibernateProperties());
        return sessionFactoryBean;
    }
    //獲取hibernate配置
    private Properties hibernateProperties() {
        Properties properties = new Properties();
        properties.setProperty("hibernate.current_session_context_class", environment.getProperty("spring.jpa.properties.hibernate.current_session_context_class"));
        properties.setProperty("hibernate.hbm2ddl.auto", environment.getProperty("spring.jpa.hibernate.ddl-auto"));
        properties.setProperty("hibernate.show-sql", environment.getProperty("spring.jpa.properties.hibernate.show-sql"));
        properties.setProperty("hibernate.cache.use_second_level_cache", environment.getProperty("spring.jpa.properties.hibernate.cache.use_second_level_cache"));
        properties.setProperty("hibernate.cache.use_query_cache", environment.getProperty("spring.jpa.properties.hibernate.cache.use_query_cache"));
        return properties;
    }
}

解決方法2：降低hibernate版本

<properties>
    <java.version>1.8</java.version>
    <hibernate.version>5.0.12.Final</hibernate.version>
</properties>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>${hibernate.version}</version>
</dependency>
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-entitymanager</artifactId>
    <version>${hibernate.version}</version>
</dependency>
`

getCurrentSession導緻的(of)問題

問題1：org.hibernate.HibernateException: No CurrentSessionContext configured!

application.properties

spring.jpa.properties.hibernate.current_session_context_class=org.springframework.orm.hibernate5.SpringSessionContext

問題2：Could not obtain transaction-synchronized Session for current thread

這(this)個(indivual)問題就是(yes)因爲(for)session是(yes)用(use)getCurrentSession()獲取，但是(yes)方法上沒有開啓事務導緻。

consider declaring the factory method as static for independence from its containing instance
待查

參考資料
https://www.jianshu.com/p/57e3c9a40709
https://blog.csdn.net/qq_15329947/article/details/85232287
https://blog.csdn.net/xiaonannew/article/details/82634241
https://blog.csdn.net/wt592376761/article/details/104797009