• thread: Session 对象的生命周期与本地线程绑定
• jta*: Session 对象的生命周期与 JTA 事务绑定
• managed: Hibernate 托付程序来管理 Session 对象的生命周期

Session 对象的生命周期与本地线程绑定

• 当一个线程(threadA)第一次调用 SessionFactory 对象的 getCurrentSession() 方法时, 该方法会创建一个新的 Session(sessionA) 对象, 把该对象与 threadA 绑定, 并将 sessionA 返回
• 当 threadA 再次调用 SessionFactory 对象的 getCurrentSession() 方法时, 该方法将返回 sessionA 对象
• 当 threadA 提交 sessionA 对象关联的事务时, Hibernate 会自己主动flush sessionA 对象的缓存, 然后提交事务, 关闭 sessionA 对象. 当 threadA 撤销 sessionA 对象关联的事务时, 也会自己主动关闭 sessionA 对象
• 若 threadA 再次调用 SessionFactory 对象的 getCurrentSession() 方法时, 该方法会又创建一个新的 Session(sessionB) 对象, 把该对象与 threadA 绑定, 并将 sessionB 返回

package com.atguigu.hibernate.hibernate;import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;public class HibernateUtils {private HibernateUtils(){}private static HibernateUtils instance = new HibernateUtils();public static HibernateUtils getInstance() {return instance;}private SessionFactory sessionFactory;public SessionFactory getSessionFactory() {if (sessionFactory == null) {Configuration configuration = new Configuration().configure();ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();sessionFactory = configuration.buildSessionFactory(serviceRegistry);}return sessionFactory;}public Session getSession(){return getSessionFactory().getCurrentSession();}}

package com.atguigu.hibernate.dao;import org.hibernate.Session;import com.atguigu.hibernate.entities.Department;
import com.atguigu.hibernate.hibernate.HibernateUtils;public class DepartmentDao {public void save(Department dept){//内部获取 Session 对象//获取和当前线程绑定的 Session 对象//1. 不须要从外部传入 Session 对象//2. 多个 DAO 方法也能够使用一个事务!Session session = HibernateUtils.getInstance().getSession();System.out.println(session.hashCode());session.save(dept);}/*** 若须要传入一个 Session 对象, 则意味着上一层(Service)须要获取到 Session 对象.* 这说明上一层须要和 Hibernate 的 API 紧密耦合. 所以不推荐使用此种方式. */public void save(Session session, Department dept){session.save(dept);}}

Test

package com.atguigu.hibernate.test;import java.sql.Connection;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Conjunction;
import org.hibernate.criterion.Disjunction;
import org.hibernate.criterion.MatchMode;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.hibernate.jdbc.Work;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;import com.atguigu.hibernate.dao.DepartmentDao;
import com.atguigu.hibernate.entities.Department;
import com.atguigu.hibernate.entities.Employee;
import com.atguigu.hibernate.hibernate.HibernateUtils;public class HibernateTest {private SessionFactory sessionFactory;private Session session;private Transaction transaction;@Beforepublic void init(){Configuration configuration = new Configuration().configure();ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();sessionFactory = configuration.buildSessionFactory(serviceRegistry);session = sessionFactory.openSession();transaction = session.beginTransaction();}@Afterpublic void destroy(){transaction.commit();session.close();sessionFactory.close();}@Testpublic void testManageSession(){//获取 Session//开启事务Session session = HibernateUtils.getInstance().getSession();System.out.println("-->" + session.hashCode());Transaction transaction = session.beginTransaction();DepartmentDao departmentDao = new DepartmentDao();Department dept = new Department();dept.setName("ATGUIGU");departmentDao.save(dept);departmentDao.save(dept);departmentDao.save(dept);//若 Session 是由 thread 来管理的, 则在提交或回滚事务时, 已经关闭 Session 了. transaction.commit();System.out.println(session.isOpen()); }}

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC"-//Hibernate/Hibernate Configuration DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration><session-factory><!-- Hibernate 连接数据库的基本信息 --><property name="connection.username">scott</property><property name="connection.password">java</property><property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property><property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property><!-- Hibernate 的基本配置 --><!-- Hibernate 使用的数据库方言 --><property name="dialect">org.hibernate.dialect.Oracle10gDialect</property><!-- 执行时是否打印 SQL --><property name="show_sql">true</property><!-- 执行时是否格式化 SQL --><property name="format_sql">true</property><!-- 生成数据表的策略 --><property name="hbm2ddl.auto">update</property><!-- 设置 Hibernate 的事务隔离级别 --><property name="connection.isolation">2</property><!-- 删除对象后, 使其 OID 置为 null --><property name="use_identifier_rollback">true</property><!-- 配置 C3P0 数据源 --><!--  <property name="hibernate.c3p0.max_size">10</property><property name="hibernate.c3p0.min_size">5</property><property name="c3p0.acquire_increment">2</property><property name="c3p0.idle_test_period">2000</property><property name="c3p0.timeout">2000</property><property name="c3p0.max_statements">10</property>--><!-- 设定 JDBC 的 Statement 读取数据的时候每次从数据库中取出的记录条数 --><property name="hibernate.jdbc.fetch_size">100</property><!-- 设定对数据库进行批量删除，批量更新和批量插入的时候的批次大小 --><property name="jdbc.batch_size">30</property><!-- 启用二级缓存 --><property name="cache.use_second_level_cache">true</property><!-- 配置使用的二级缓存的产品 --><property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property><!-- 配置启用查询缓存 --><property name="cache.use_query_cache">true</property><!-- 配置管理 Session 的方式 --><property name="current_session_context_class">thread</property><!-- 须要关联的 hibernate 映射文件 .hbm.xml --><mapping resource="com/atguigu/hibernate/entities/Department.hbm.xml"/><mapping resource="com/atguigu/hibernate/entities/Employee.hbm.xml"/><class-cache usage="read-write" class="com.atguigu.hibernate.entities.Employee"/><class-cache usage="read-write" class="com.atguigu.hibernate.entities.Department"/><collection-cache usage="read-write" collection="com.atguigu.hibernate.entities.Department.emps"/></session-factory>
</hibernate-configuration>