数据库
use demo;select * from CLASSINFO;select * from persons;delete from CLASSINFO;delete from persons;insert into CLASSINFO values('c111','banji1');insert into CLASSINFO values('c222','banji2');insert into persons values('p1','p111','c111')insert into persons values('p2','p222','c111')insert into persons values('p3','p333','c222')insert into persons values('p4','p444','c222')insert into persons values('p5','p555',null)select pid,name from persons order by pid desc;--降序select pid,name from persons order by pid asc;--升序select COUNT(*),name from persons group by nameselect (select pid,name from persons),p.rci from persons p left join CLASSINFO c on p.rci=c.cid group by p.rci;
使用双向一对多多对一的案例
实体人，班级不变；实体映射文件不变；配置文件不变
班级dao包
package dao;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import shuang.m2oo2m.ClassInfo;import util.HibernateUtil;public class ClassInfoDao { /*public void insert(){ SessionFactory sf = HibernateUtil.getSessionFactory(); Session s = sf.openSession(); Transaction tx = s.beginTransaction(); ClassInfo ci = new ClassInfo(); ci.setCid("xxx"); ci.setName("xxxx"); s.save(ci); tx.commit(); s.close(); }*/ /*public void insert(Session s,Transaction tx){ SessionFactory sf = HibernateUtil.getSessionFactory(); //Session s = sf.openSession(); //Transaction tx = s.beginTransaction(); ClassInfo ci = new ClassInfo(); ci.setCid("xxx"); ci.setName("xxxx"); s.save(ci); // tx.commit(); //s.close(); }*/ //4. public void insert(){ Session s = HibernateUtil .getSessionFactory() .getCurrentSession(); System.out.println("第二次调用getCurrentSession" + s.hashCode()); ClassInfo ci = new ClassInfo(); ci.setCid("xxx"); ci.setName("xxxx"); s.save(ci); }}
人dao包
package dao;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import shuang.m2oo2m.*;import util.HibernateUtil;public class PersonDao { /* * 1.往person表里面添加一条记录 */ /*public void insert(){ SessionFactory sf = HibernateUtil.getSessionFactory(); Session s = sf.openSession(); Transaction tx = s.beginTransaction(); Person p = new Person(); p.setPid("p6"); p.setName("xxx"); s.save(p); tx.commit(); s.close(); }*/ //2. /*public void insert(Session s){ SessionFactory sf = HibernateUtil.getSessionFactory(); Transaction tx = s.beginTransaction(); Person p = new Person(); p.setPid("p6"); p.setName("xxx"); s.save(p); tx.commit(); //s.close(); }*/ //3 /*public void insert(Session s,Transaction tx){ SessionFactory sf = HibernateUtil.getSessionFactory(); //Transaction tx = s.beginTransaction(); Person p = new Person(); p.setPid("p6"); p.setName("xxx"); s.save(p); //tx.commit(); //s.close(); }*/ //4. public void insert(){ Session s = HibernateUtil .getSessionFactory() .getCurrentSession(); System.out.println("第1111次调用getCurrentSession" + s.hashCode()); Person p = new Person(); p.setPid("p6"); p.setName("xxx"); s.save(p); }}
业务
package service;import dao.ClassInfoDao;import dao.PersonDao;import util.HibernateUtil;public class ClassPersonService { /* * 这个方法的作用是用来 * 同时插入一个人和一个班级信息 */ private PersonDao pdao= new PersonDao(); private ClassInfoDao cdao = new ClassInfoDao(); public void insert(){ //1.第一次，用来表明为什么session //要从service类里传到dao里 //初始的时候，每一个dao的方法都有自己的session与事务对象 //也就是每个方法都是独立的 //每次一个业务，对应多个dao对象的多个方法或者 //一个dao对象的多个方法，都打开了多个session（关联了jdbc connection） //这样是资源浪费 //同时也导致是不同的事务 /*pdao.insert(); cdao.insert();*/ //2.第二次改造 //这次的改造是让多个方法用同一个session //解决了多session（意味着多个jdbc connection）的 //资源浪费问题 //但是仍然存在不同同一个事务里面的问题 /*Session s = HibernateUtil.getSessionFactory().openSession(); pdao.insert(s); cdao.insert(s); s.close();*/ //3.下面的这次改造就是同一个session，同一个事物。 //解决了session的资源浪费问题以及多个不同事务的问题 /* Session s = HibernateUtil.getSessionFactory().openSession(); Transaction tx = s.beginTransaction(); pdao.insert(s,tx); cdao.insert(s,tx); tx.commit(); s.close();*/ //4. /* Session s = HibernateUtil.getSessionFactory().getCurrentSession(); Transaction tx = s.getTransaction(); pdao.insert(); cdao.insert(); tx.commit();*/ /* Session s = HibernateUtil.getSessionFactory().getCurrentSession(); s.getTransaction().begin();//创建一个事务 pdao.insert(); cdao.insert(); s.getTransaction().commit(); */ HibernateUtil.getSessionFactory() .getCurrentSession() .getTransaction() .begin();//创建一个事务 pdao.insert(); cdao.insert(); HibernateUtil.getSessionFactory() .getCurrentSession() .getTransaction() .commit();//当事务提交时，此事务关联的session会自动帮你关闭 /*与此服务类的代理类配合使用 * pdao.insert(); cdao.insert();*/ }}
Main测试
package com.nf;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import service.ClassPersonService;import util.HibernateUtil;public class Main { public static void main(String[] args) { ClassPersonService service = new ClassPersonService(); service.insert(); } private static void template() { SessionFactory sf = HibernateUtil.getSessionFactory(); Session s = sf.openSession(); Transaction tx = s.beginTransaction(); tx.commit(); s.close(); sf.close(); }}
使用代理改进版
前面不变，业务变
package service;import util.HibernateUtil;public class ClassPersonServiceProxy extends ClassPersonService { public void insert() { HibernateUtil.getSessionFactory() .getCurrentSession() .getTransaction() .begin();//创建一个事务 super.insert(); HibernateUtil.getSessionFactory() .getCurrentSession() .getTransaction() .commit(); }}
Main测试变
package com.nf;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import service.ClassPersonServiceProxy;import util.HibernateUtil;public class Main { public static void main(String[] args) { ClassPersonServiceProxy service = new ClassPersonServiceProxy(); service.insert(); } private static void template() { SessionFactory sf = HibernateUtil.getSessionFactory(); Session s = sf.openSession(); Transaction tx = s.beginTransaction(); tx.commit(); s.close(); sf.close(); }}