为什么openSession不起作用,但getCurrentSession在Spring Hibernate中工作

Question

我已经编写了一个示例Spring Hibernate应用程序o了解Spring hibernate集成的工作原理.

这是我的applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd">

    <context:component-scan base-package="com.general" />

    <tx:annotation-driven />

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
        <property name="url" value="jdbc:oracle:thin:@localhost:1521:orcl" />
        <property name="username" value="system" />
        <property name="password" value="admin_123" />
    </bean>

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean ">
        <property name="dataSource" ref="dataSource"></property>
        <property name="packagesToScan" value="com.general"></property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>

    <bean id="transactionManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>
</beans>

然后,我的服务类就是这样

package com.general;

import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;


@Service("employeeService")
public class EmployeeServiceImpl implements EmployeeService{

    @Autowired
    private SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    @Transactional
    public void saveEmployee(Employee emp) {
        Session session = sessionFactory.getCurrentSession();//.openSession();
        session.save(emp);
    }

}

而我的主要课程是

public class App {

    public static void main(String[] args) {
        System.out.println("load context");
        ConfigurableApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        Employee em = new Employee();
        em.setId(1l);
        em.setName("John");

        EmployeeService emService = (EmployeeService) context.getBean("employeeService");
        emService.saveEmployee(em);
    }

}

如果我使用getCurrentSession方法运行此应用程序,那么它运行正常并且员工被保存到数据库中但是如果我使用openSession方法,则不会触发任何SQL查询,因此不会将任何内容保存到数据库中.

我不确定为什么会这样.可能是我对getCurrentSession()和openSession()没有正确的理解.请有人让我知道背后的原因.

Answer 1

您@Transactional在一个带@Service注释的类中使用方法的事实以及一个TransactionManager意味着整个事务生命周期将由Spring管理.

当你的saveEmployee方法被调用时,Spring将打开一个Session,启动一个事务,执行你的代码,提交事务并关闭Session.在Session它开始被绑定到当前线程,可通过getCurrentSession().

如果您改为使用openSession(),那么您将打开一个完全不相关的 Session,而不是由Spring管理的TransactionManager.因此, 交易将不会被提交,Session除非您自己执行,否则不会关闭.