lazy 懒加载默认为proxy

继承映射

discriminant column="type" type="string"

集合映射

生成表的语句：

public class DbCreate {

public static void main(String[] args) {

Configuration cfg=new Configuration().configure("/hibernate.cfg.xml");

SchemaExport exprot=new SchemaExport(cfg);

exprot.create(true, true);

}

集合的实体

private String id;

private String name;

private Set setValue;

private List listValue;

private String[] arrayValue;

private Map mapValue;

该配置文件

<hibernate-mapping>

</id>

</property>

</set>

<list-index column="list_index"/>

</list>

<list-index column="array_index"/>

</array>

<map-key type="string" column="map_key"/>

</map>

</class>

</hibernate-mapping>

生成的表结构

自己写的crud

package com.pcx.dao;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import org.hibernate.Hibernate;

import org.hibernate.Session;

import org.hibernate.Transaction;

import com.pcx.model.Collection;

import com.pcx.util.HibernateSessionFactory;

public class CollTest {

public void testQueryColl(String id){

Session session=HibernateSessionFactory.getSession();

Collection c=(Collection) session.get(Collection.class, id);

List list=c.getListValue();

for (Object o : list) {

System.out.println(o);

}

HibernateSessionFactory.closeSession();

}

public void testColl(){

Collection c=new Collection();

c.setName("测试");

String[]ss={"a","b","c","d"};

ArrayList<String>list=new ArrayList<String>();

list.add("a");

list.add("c");

list.add("e");

HashSet<String>set=new HashSet<String>();

set.add("1");

set.add("3");

set.add("aaaa");

HashMap<String, String>map=new HashMap<String, String>();

map.put("1", "11");

map.put("2", "22");

map.put("3", "33");

c.setArrayValue(ss);

c.setListValue(list);

c.setSetValue(set);

c.setMapValue(map);

Session session=HibernateSessionFactory.getSession();

Transaction tx=session.beginTransaction();

session.save(c);

tx.commit();

HibernateSessionFactory.closeSession();

}

public static void main(String[] args) {

CollTest test=new CollTest();

// test.testColl();

test.testQueryColl("4028d0814ecd7aa4014ecd7aa66c0001");

}

组合映射

两个实体类对应生成一张表格

Emp类：

private String id;

private String name;

private Address address;

对应的地址类：address类

private String homeAddress;

private String comAddress;

对应的配置文件

<hibernate-mapping>

</id>

</property>

</component>

</class>

</hibernate-mapping>

对应生成的表结构为

自己写的crud

package com.pcx.dao;

import org.hibernate.Session;

import org.hibernate.Transaction;

import com.pcx.model.Address;

import com.pcx.model.Emp;

import com.pcx.util.HibernateSessionFactory;

public class ComponentTest {

public void testCom(){

Session session=HibernateSessionFactory.getSession();

Transaction tx=session.beginTransaction();

Address ad=new Address();

ad.setComAddress("济南长清");

ad.setHomeAddress("山东泰安");

Emp e=new Emp();

e.setName("程志");

e.setAddress(ad);

session.save(e);

tx.commit();

HibernateSessionFactory.closeSession();

}

public void testQueryCom(String id){

Session session=HibernateSessionFactory.getSession();

Emp e=(Emp) session.get(Emp.class,id );

System.out.println(e.getId());

System.out.println(e.getName());

System.out.println(e.getAddress().getHomeAddress());

}

public static void main(String[] args) {

ComponentTest com=new ComponentTest();

// com.testCom();

com.testQueryCom("4028d0814ece0647014ece0648f20001");

}

联合主键

如果一个表没主键，那么由表生成类的时候会单独生成一个 id类

Student 类中就单独一个StudentId

StudentId中则包含 id name

生成的配置文件为：

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!--

Mapping file autogenerated by MyEclipse Persistence Tools

-->

<hibernate-mapping>

<composite-id name="id" class="com.pcx.model.StudentId">

<key-property name="id" type="java.lang.Integer">

</key-property>

<key-property name="name" type="java.lang.String">

</key-property>

</composite-id>

</class>

</hibernate-mapping>

在一个例子

Emp

private PKId pkid;

private String name;

PKId

private Integer fristId;

private Integer lastId;

配置文件：

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

<composite-id name="pkid">

<key-property name="fristId" />

<key-property name="lastId" />

</composite-id>

</property>

</class>

</hibernate-mapping>

配置文件字段配置错了可能会出现

类的变量没配对

提示错误找不到配置文件。

多对多关系

多个学生对应多个老师

学生

private String id;

private String name;

private Set<Teacher> teachers;

老师

private String id;

private String name;

private Set<Student> students;

配置文件

学生

<hibernate-mapping>

</id>

</property>

<many-to-many class="com.pcx.entity.Teacher" column="tid" ></many-to-many>

</set>

</class>

</hibernate-mapping>

老师

<hibernate-mapping>

</id>

</property>

<many-to-many class="com.pcx.entity.Student" column="sid"></many-to-many>

</set>

</class>

</hibernate-mapping>

对应的crud

package com.pcx.dao;

import java.util.HashSet;

import java.util.Set;

import org.hibernate.Session;

import org.hibernate.Transaction;

import com.pcx.entity.Student;

import com.pcx.entity.Teacher;

import com.pcx.util.HibernateSessionFactory;

public class TestManyToMany {

private void testManyToMany(){

Session session=HibernateSessionFactory.getSession();

Transaction tx=session.beginTransaction();

Teacher t1=new Teacher();

t1.setName("彭");

Teacher t2=new Teacher();

t2.setName("李");

Student s1=new Student();

Student s2=new Student();

Student s3=new Student();

Student s4=new Student();

s1.setName("aaa");

s2.setName("aaa");

s3.setName("bbb");

s4.setName("aaa");

Set<Teacher>set=new HashSet<Teacher>();

set.add(t1);set.add(t2);

s1.setTeachers(set);

session.save(s1);

tx.commit();

HibernateSessionFactory.closeSession();

}

public void testQuery(String id){

Session session=HibernateSessionFactory.getSession();

Teacher t=(Teacher) session.get(Teacher.class, id);

System.out.println(t.getName());

Set<Student>ss=t.getStudents();

for (Student student : ss) {

System.out.println(student.getName());

}

HibernateSessionFactory.closeSession();

}

public static void main(String[] args) {

TestManyToMany test=new TestManyToMany();

// test.testManyToMany();

test.testQuery("4028d0814ece5103014ece51053b0002");

}

一对一

查询

Hql

懒加载的问题

一对多的表关系中默认是proxy

true 不加载关联的老师查出来学生不被加载了

false 加载关联的

enchor代理

load验证id在表中是否存在，不加载其他的属性，若不关闭Session 可以取出name 因为被代理掉了

同Query类的iterator

查询一个单体的时候

根据ID来查询 get load

get直接发送sql语句，直接将数据从数据库中加载到当前程序中，并且置入对象属性。

load不发送sql语句，只是查询当前给定的id在数据库中是否有这样一条记录对应存在

协助维护数据关系的

可以通过forward --过滤器用于开启或关闭Session

unionQueresult()

分页

Criteria类

gt 大于1000的

lt 小于1000的

复合条件

.add().add()

排序 addorder

ReStrictions

结合离线查询

查询的案例代码

package com.pcx.dao;

import java.util.List;

import org.hibernate.Criteria;

import org.hibernate.Query;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.hibernate.criterion.DetachedCriteria;

import org.hibernate.criterion.Order;

import org.hibernate.criterion.Restrictions;

import com.pcx.model1.Emp;

import com.pcx.util.HibernateSessionFactory;

public class QueryTest {

public static void initDate(){

Session session=HibernateSessionFactory.getSession();

Transaction tx=session.beginTransaction();

for (int i = 0; i < 100; i++) {

Emp e=new Emp();

e.setName("张三"+i);

session.save(e);

}

tx.commit();

HibernateSessionFactory.closeSession();

}

public static List<Emp> hql1(){

Session session=HibernateSessionFactory.getSession();

String hql=" from Emp e where e.sal>1000";

Query query=session.createQuery(hql);

List<Emp>emps=query.list();

for (Emp emp : emps) {

System.out.println(emp);

}

HibernateSessionFactory.closeSession();

return emps;

}

/**

* 查询的第二种情况

* @param args

public static void hql2(){

Session session=HibernateSessionFactory.getSession();

String hql="select name,age from Emp ";

Query query=session.createQuery(hql);

List emps=query.list();

Object[]obj=(Object[]) emps.get(0);

String name=(String) obj[0];

Integer age=(Integer) obj[1];

System.out.println("name:"+name+" age:"+age);

HibernateSessionFactory.closeSession();

}

/**

* 绑定变量

* @param args

public static void bindVar(){

Session session=HibernateSessionFactory.getSession();

String hql="from Emp where name=:name";

Query q=session.createQuery(hql);

q.setParameter("name", "张三");

List<Emp>list=q.list();

System.out.println( list.get(0));;

HibernateSessionFactory.closeSession();

}

// 使用Criteria

public static void load1(){

Session s=HibernateSessionFactory.getSession();

Criteria c=s.createCriteria(Emp.class);

//这个Criteria绝大多数的应用是增加条件

// c.add(Restrictions.eq("name", "李四"));

// c.add(Restrictions.between("sal", 1000.00, 5000.00));

// c.add(Restrictions.gt("age", 20));//大于

// c.add(Restrictions.lt("age", 20));//小于

// c.add(null).add(null);//可以不停的去add 节省了拼sql的时间

// c.add(Restrictions.like("name", "李%"));

// c.setFirstResult(0);

// c.setMaxResults(20);

c.addOrder(Order.asc("sal"));

List<Emp>list=c.list();

for (Emp emp : list) {

System.out.println(emp);

}

HibernateSessionFactory.closeSession();

}

//离线查询脱离Session 创建查询

public static void load2(){

Session session=HibernateSessionFactory.getSession();

DetachedCriteria dc=DetachedCriteria.forClass(Emp.class);

dc.add(Restrictions.eq("name", "李四"));

List<Emp>list=dc.getExecutableCriteria(session).list();

for (Emp emp : list) {

System.out.println(emp);

}

HibernateSessionFactory.closeSession();

}

//分页查询

public static void load3(int firstRow,int maxResult){

Session session=HibernateSessionFactory.getSession();

Query query=session.createQuery("from Emp");

query.setFirstResult(firstRow);

query.setMaxResults(maxResult);

List<Emp>list=query.list();

for (Emp emp : list) {

System.out.println(emp);

}

HibernateSessionFactory.closeSession();

}

//分页查询二

public static void load4(int currentPage){

int pageSize=10;

int totalPageSize=(int)getTotalSize();

int pageCount=totalPageSize/pageSize;

if (totalPageSize%pageSize!=0) {

pageCount++;

}

System.out.println("共"+pageCount+"页");

System.out.println("共"+totalPageSize+"条记录");

//如果客户给出的当前页小于 1 则给当前页赋值1 防止负数的出现

if (currentPage<1) {

currentPage=1;

}

//如果客户给出的当前页大于总页数。则给当前页赋值为最大页数

if(currentPage>pageCount){

currentPage = pageCount;

}

Session session = HibernateSessionFactory.getSession();

String hql = "from Emp order by id";

Query query = session.createQuery(hql);

query.setFirstResult((currentPage-1)*pageSize);

query.setMaxResults(pageSize);

List<Emp> list = query.list();

for (Emp emp : list) {

System.out.println(emp.getId());

System.out.println(emp.getName());

}

HibernateSessionFactory.closeSession();

}

private static long getTotalSize() {

Session session = HibernateSessionFactory.getSession();

String hql ="select count(*) from Emp";

Query query = session.createQuery(hql);

List list = query.list();

Object obj = list.get(0);

return (Long) obj;

}

public static void main(String[] args) {

// List<Emp>emps=hql1();

//Session已经关闭，加载不了对象如果开启懒加载的话就不会报错

// for (Emp emp : emps) {

// System.out.println(emp);

// }

// hql2();

// bindVar();

// load2();

initDate();

}

Hibernate笔记③--集合映射、组合映射、联合主键、查询案例

集合映射

组合映射

联合主键

多对多关系

查询

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