为什么openSession不工作，但getCurrentSession在Spring Hibernate中起作用 [英] Why doesn't openSession work but getCurrentSession works in Spring Hibernate
问题描述
这是我的applicationContext.xml
< beans xmlns =http://www.springframework.org/schema/beans
xmlns：xsi =http：//www.w3 .org / 2001 / XMLSchema-instancexmlns：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/jeexmlns：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 =driverClassNamevalue =oracle.jdbc.driver.OracleDriver/>
< property name =urlvalue =jdbc：oracle：thin：@localhost：1521：orcl/>
< property name =usernamevalue =system/>
< property name =passwordvalue =admin_123/>
< / bean>
< bean id =sessionFactory
class =org.springframework.orm.hibernate4.LocalSessionFactoryBean>
< property name =dataSourceref =dataSource>< / property>
< property name =packagesToScanvalue =com.general>< / property>
< property name =hibernateProperties>
<道具>
< prop key =hibernate.dialect> org.hibernate.dialect.Oracle10gDialect< / prop>
< prop key =hibernate.show_sql> true< / prop>
< /道具>
< / property>
< / bean>
< bean id =transactionManager
class =org.springframework.orm.hibernate4.HibernateTransactionManager>
< property name =sessionFactoryref =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;
$ b @Service（employeeService）
public class EmployeeServiceImpl implements EmployeeService {
$ b $ @Autowired
private SessionFactory sessionFactory;
public void setSessionFactory（SessionFactory sessionFactory）{
this.sessionFactory = sessionFactory;
$ b @Transactional
public void saveEmployee（Employee emp）{
Session session = sessionFactory.getCurrentSession（）; //。openSession（）;
session.save（emp）;
}
}
我的主类是 p>
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，那么它运行良好，雇员被保存到数据库中，但是如果我使用openSession方法，则不会触发SQL查询，因此不会将任何数据保存到数据库中。
我不知道为什么会发生这种情况。可能是我对getCurrentSession（）和openSession（）没有正确的理解。
事实上，您有 @Transactional 对 @Service 带注释的类中的方法以及 TransactionManager 意味着整个事务生命周期将被Spring管理。
当调用 saveEmployee 方法时，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 。它启动的 Session 绑定到当前线程，并可通过 getCurrentSession（）获得。
如果您改为使用 openSession（），您打开完全不相关 Session ，而不是由Spring的 TransactionManager 管理。因此，交易不会被提交，并且 Session 不会被关闭，除非您自己做。
I have written a sample Spring Hibernate application o understand how Spring hibernate integration works.
Here is my 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>
Then, my service class is like that
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);
}
}
And my main class is
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);
}
}
If I run this application using getCurrentSession method, then it runs fine and employee is saved into the database but if i use openSession method, then no SQL query is fired and thus nothing is saved into the database.
I am not sure why this is happening. May be I don't have correct understanding of getCurrentSession () and openSession (). Can please someone let me know the reason behind it.
The fact that you have @Transactional on a method in a @Service annotated class along with a TransactionManager means the whole transaction lifecycle will be managed by Spring.
When your saveEmployee method is called, Spring will open a Session, start a transaction, execute your code, commit the transaction and close the Session. The Session it starts is bound to the current thread and available through getCurrentSession().
If you instead use openSession(), you are opening a completely unrelated Session, not managed by Spring's TransactionManager. As such, the transaction won't be committed and the Sessionwon't be closed unless you do it yourself.
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