hibernate课程 初探单表映射2-5 session详解（上）

1　　　　本章目的：获得session的两种方式：

openSession 和 getCurrentSession

2　　　　两种session的使用方法

1openSession可以直接写，getCurrentSession需要在cfg.xml中配置

2 getCurrentSession创建的线程会在事务回滚或事物提交后自动关闭,而openSession必须手动关闭

这里getCurrentSession本地事务(本地事务:jdbc)时 要在配置文件里进行如下设置

 * 如果使用的是本地事务（jdbc事务）  <property name="hibernate.current_session_context_class">thread</property>

 * 如果使用的是全局事务（jta事务）  <property name="hibernate.current_session_context_class">jta</property> 

3　　　　两种session用途不同之出

 getCurrentSession创建的session会和绑定到当前线程,而openSession不会。

demo：

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>
     <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
     <property name="connection.url">jdbc:mysql://localhost:3306/bendi</property>
     <property name="connection.username">root</property>
     <property name="connection.password">weidou318</property>
     <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
     
     <property name="show_sql">true</property>
     <property name="format_sql">true</property>
     <property name="hbm2ddl.auto">create</property>
     
     <property name="hibernate.current_session_context_class">thread</property>
  
  <mapping resource = "Student.hbm.xml"/>     
    </session-factory>
</hibernate-configuration>

StudentTest.java

package hibernate_001;

import java.sql.Array; import java.sql.Blob; import java.sql.CallableStatement; import java.sql.Clob; import java.sql.DatabaseMetaData; import java.sql.NClob; import java.sql.PreparedStatement; import java.sql.SQLClientInfoException; import java.sql.SQLException; import java.sql.SQLWarning; import java.sql.SQLXML; import java.sql.Savepoint; import java.sql.Statement; import java.sql.Struct; import java.util.Date; import java.util.Map; import java.util.Properties; import java.util.TimeZone; import java.util.concurrent.Executor;

import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.hibernate.jdbc.Work; import org.hibernate.metamodel.SessionFactoryBuilder; import org.hibernate.service.ServiceRegistry; import org.hibernate.service.ServiceRegistryBuilder; import org.junit.After; import org.junit.Before; import org.junit.Test;

import com.ddwei.student.Student; import com.mysql.jdbc.Connection; import com.mysql.jdbc.ExceptionInterceptor; import com.mysql.jdbc.Extension; import com.mysql.jdbc.MySQLConnection; import com.mysql.jdbc.log.Log;

public class StudentTest {    private SessionFactory sessionFactory;  private Session session;  private Transaction trasaction;    @Test  public void testSaveStudent1(){   Configuration config = new Configuration().configure();   ServiceRegistry serviceRe = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();   SessionFactory sessionFactory = config.buildSessionFactory(serviceRe);   Session session = sessionFactory.openSession(); //  Student student =new Student(3,"周恩来","男",new Date(),"绍兴");//创建学生对象 //  session.save(student);//会话保存学生对象进入数据库        }      @Test  public void testSaveStudent2(){      Configuration config = new Configuration().configure();   ServiceRegistry serviceRe = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();   SessionFactory sessionFactory = config.buildSessionFactory(serviceRe);   Session session = sessionFactory.getCurrentSession(); //  Student student =new Student(3,"周恩来","男",new Date(),"绍兴");//创建学生对象 //  session.save(student);//会话保存学生对象进入数据库           }    

}