【7.3】

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.siggy.pojo">
	<class name="Grade">
		<id name="id">
			<generator class="native"></generator>
		</id>
		<property name="name"/>
		<!-- set是 Grade中的集合属性  name属性名称 -->
		<set name="students" cascade="delete">
			<!-- key表示外键  column外键列名-->
			<key column="grade_id"></key>
			<!-- one-to-many 一对多  类Grade 中  students 所表示类型 -->
			<one-to-many class="Student"/>
		</set>
	</class>
</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.siggy.pojo">
	<class name="Student">
		<id name="id">
			<generator class="native"></generator>
		</id>
		<property name="name"/>
		<property name="age"/>
		<!-- 
			cascade 级联：让操作级联到子实体 
			save-update：保存和更新多的一端数据时，一的一端的数据可以一起保存和更新
			none:不级联
			delete：删除级联-不能在多的一端使用
			all:表示所有操作都级联
		 -->
		<many-to-one name="grade" class="Grade" column="grade_id" cascade="save-update"></many-to-one>
	</class>
</hibernate-mapping>

package cn.siggy.test;

import java.sql.SQLException;

import javax.sql.rowset.serial.SerialException;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

import cn.siggy.pojo.Grade;
import cn.siggy.pojo.Student;
import cn.siggy.util.HibernateUtil;

public class HibernateTest {
	@Test
	public void testCreateDB(){
		Configuration cfg = new Configuration().configure();
		SchemaExport se = new SchemaExport(cfg);
		//第一个参数 是否生成ddl脚本  第二个参数  是否执行到数据库中
		se.create(true, true);
	}
	@Test
	public void testSave() throws HibernateException, SerialException, SQLException{
		Session session = null;
		Transaction tx = null;
		try{
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			Grade grade = new Grade();
			grade.setName("基础");
			
			Student stu = new Student();
			stu.setName("张三疯");
			stu.setAge(22);
			stu.setGrade(grade);
			Student stu1 = new Student();
			stu1.setName("老王");
			stu1.setAge(23);
			stu1.setGrade(grade);
			
			grade.getStudents().add(stu);
			grade.getStudents().add(stu1);
//			session.save(grade);
			session.save(stu);
			session.save(stu1);
			
			tx.commit();
			
		}catch (HibernateException e) {
			if(tx!=null)
				tx.rollback();
			e.printStackTrace();
			throw e;
		}finally{
			HibernateUtil.closeSession();
		}
	}
	@Test
	public void testGet(){
		Session session = null;
		Transaction tx = null;
		try{
			session = HibernateUtil.getSession();
			tx = session.beginTransaction();
			
			Grade grade = (Grade)session.get(Grade.class, 1);
			session.delete(grade);
			tx.commit();
		}catch (HibernateException e) {
			if(tx!=null)
				tx.rollback();
			e.printStackTrace();
			//throw e;
		}finally{
			HibernateUtil.closeSession();
		}
	}
}