JavaWeb学习：Hibernate抓取策略
Hibernate性能优化的手段：缓存、抓取策略
抓取策略不会单独使用，抓取策略通常和延迟加载一起使用
一、延迟加载
①、延迟加载：lazy（懒加载）。执行到该行代码的时候，不会发送语句去进行查询，在真正使用这个对象的属性的时候才会发送SQL语句进行查询。
②、延迟加载的分类
2.1、类级别的延迟加载
指的是通过load方法查询某个对象的时候，是否采用延迟。session.load(Customer.class,1l);
2.1.1、类级别延迟加载失效
2.1.1.1、*.hbm.xml修改class 的lazy的值
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 建立类与表的映射 --> <class name="com.hibernate.domain.Customer" table="cst_customer" lazy="false">
2.1.1.2、将持久化类使用final修饰
2.1.1.3、Hibernate. Initialize()
@Test public void demo12() { Session session = HibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); Customer customer=session.load(Customer.class, 1l); Hibernate.initialize(customer); transaction.commit(); }
2.2、关联级别的延迟加载
指的是在查询到某个对象的时候，查询其关联的对象的时候，是否采用延迟加载。
Customer customer = session.get(Customer.class,1l);
customer.getLinkMans();----通过客户获得联系人的时候，联系人对象是否采用了延迟加载，称为是关联级别的延迟。
抓取策略往往会和关联级别的延迟加载一起使用，优化语句。
2.2.1、抓取策略的概述
通过一个对象抓取到关联对象需要发送SQL语句，通过配置<set>或者<many-to-one>上的fetch和lazy属性优化发送的SQL语句
2.2.2、<set>上的fetch和lazy
-
-
- fetch：抓取策略，控制SQL语句格式
- select：默认值，发送普通的select语句，查询关联对象
- join：发送一条迫切左外连接查询关联对象
- subselect：发送一条子查询查询其关联对象
- lazy：延迟加载，控制查询关联对象的时候是否采用延迟
- true：默认值，查询关联对象的时候，采用延迟加载
- false：查询关联对象的时候，不采用延迟加载
- extra ：极其懒惰。
- 在实际开发中，一般都采用默认值。如果有特殊的需求，可能需要配置join
- fetch：抓取策略，控制SQL语句格式
-
Java代码：
@Test public void demo5() { Session session = HibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); Customer customer=session.get(Customer.class, 2l); System.out.println(customer.getLinkMans().size());//加断点 transaction.commit(); }
2.2.2.1、 fetch="select" lazy="true"
<!-- set标签 ： * name ：多的一方的对象集合的属性名称。 * cascade：级联 * inverse：放弃外键维护权。 --> <set name="linkMans" cascade="save-update,delete" inverse="true" fetch="select" lazy="true" >
执行到断点前结果：
Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?
执行到断点后结果：
Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? 1
2.2.2.2、 fetch="select" lazy="false"
<set name="linkMans" cascade="save-update,delete" inverse="true" fetch="select" lazy="false" >
执行到断点前结果：
Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=?
执行到断点后结果：1
2.2.2.3、 fetch="select" lazy="extra"
<set name="linkMans" cascade="save-update,delete" inverse="true" fetch="select" lazy="extra" >
执行到断点前结果：
Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?
执行到断点后结果：
Hibernate: select count(lkm_id) from cst_linkman where lkm_cust_id =? 1
2.2.2.4、 fetch="join" lazy=失效
<set name="linkMans" cascade="save-update,delete" inverse="true" fetch="join" lazy="true" >
执行到断点前结果：
Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_, linkmans1_.lkm_cust_id as lkm_cus10_1_1_, linkmans1_.lkm_id as lkm_id1_1_1_, linkmans1_.lkm_id as lkm_id1_1_2_, linkmans1_.lkm_name as lkm_name2_1_2_, linkmans1_.lkm_gender as lkm_gend3_1_2_, linkmans1_.lkm_phone as lkm_phon4_1_2_, linkmans1_.lkm_mobile as lkm_mobi5_1_2_, linkmans1_.lkm_email as lkm_emai6_1_2_, linkmans1_.lkm_qq as lkm_qq7_1_2_, linkmans1_.lkm_position as lkm_posi8_1_2_, linkmans1_.lkm_memo as lkm_memo9_1_2_, linkmans1_.lkm_cust_id as lkm_cus10_1_2_ from cst_customer customer0_ left outer join cst_linkman linkmans1_ on customer0_.cust_id=linkmans1_.lkm_cust_id where customer0_.cust_id=?
执行到断点后结果：1
2.2.2.5、 fetch="subselect" lazy="true"
@Test public void demo5() { Session session = HibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); List<Customer> list = session.createCriteria(Customer.class).list(); for (Customer customer : list) { System.out.println(customer); System.out.println(customer.getLinkMans().size());//断点 } transaction.commit(); }
<set name="linkMans" cascade="save-update,delete" inverse="true" fetch="subselect" lazy="true" >
执行到断点前结果：
Hibernate: select this_.cust_id as cust_id1_0_0_, this_.cust_name as cust_nam2_0_0_, this_.cust_source as cust_sou3_0_0_, this_.cust_industry as cust_ind4_0_0_, this_.cust_level as cust_lev5_0_0_, this_.cust_phone as cust_pho6_0_0_, this_.cust_mobile as cust_mob7_0_0_ from cst_customer this_ Customer [cust_id=1, cust_name=lisi, cust_source=1, cust_industry=null, cust_level=null, cust_phone=null, cust_mobile=null]
执行到断点后结果：
Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_1_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_name as lkm_name2_1_0_, linkmans0_.lkm_gender as lkm_gend3_1_0_, linkmans0_.lkm_phone as lkm_phon4_1_0_, linkmans0_.lkm_mobile as lkm_mobi5_1_0_, linkmans0_.lkm_email as lkm_emai6_1_0_, linkmans0_.lkm_qq as lkm_qq7_1_0_, linkmans0_.lkm_position as lkm_posi8_1_0_, linkmans0_.lkm_memo as lkm_memo9_1_0_, linkmans0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id in ( select this_.cust_id from cst_customer this_ ) 1
2.2.2.6、 fetch="subselect" lazy="false"
<set name="linkMans" cascade="save-update,delete" inverse="true" fetch="subselect" lazy="false" >
执行到断点前结果：
Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_1_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_name as lkm_name2_1_0_, linkmans0_.lkm_gender as lkm_gend3_1_0_, linkmans0_.lkm_phone as lkm_phon4_1_0_, linkmans0_.lkm_mobile as lkm_mobi5_1_0_, linkmans0_.lkm_email as lkm_emai6_1_0_, linkmans0_.lkm_qq as lkm_qq7_1_0_, linkmans0_.lkm_position as lkm_posi8_1_0_, linkmans0_.lkm_memo as lkm_memo9_1_0_, linkmans0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id in ( select this_.cust_id from cst_customer this_ ) Customer [cust_id=1, cust_name=lisi, cust_source=1, cust_industry=null, cust_level=null, cust_phone=null, cust_mobile=null]
执行到断点后结果：1
2.2.2.7、 fetch="subselect" lazy="extra"
<set name="linkMans" cascade="save-update,delete" inverse="true" fetch="subselect" lazy="extra" >
执行到断点前结果：
Hibernate: select this_.cust_id as cust_id1_0_0_, this_.cust_name as cust_nam2_0_0_, this_.cust_source as cust_sou3_0_0_, this_.cust_industry as cust_ind4_0_0_, this_.cust_level as cust_lev5_0_0_, this_.cust_phone as cust_pho6_0_0_, this_.cust_mobile as cust_mob7_0_0_ from cst_customer this_ Customer [cust_id=1, cust_name=lisi, cust_source=1, cust_industry=null, cust_level=null, cust_phone=null, cust_mobile=null]
执行到断点后结果：
Hibernate: select count(lkm_id) from cst_linkman where lkm_cust_id =? 1
2.2.3、<many-to-one>上的fetch和lazy
-
-
- fetch ：抓取策略，控制SQL语句格式。
- select：默认值，发送普通的select语句，查询关联对象。
- join：发送一条迫切左外连接。
- lazy ：延迟加载，控制查询关联对象的时候是否采用延迟。
- proxy ：默认值，proxy具体的取值，取决于另一端的<class>上的lazy的值。
- false：查询关联对象，不采用延迟。
- no-proxy：（不会使用）
- 在实际开发中，一般都采用默认值。如果有特殊的需求，可能需要配置join。
- fetch ：抓取策略，控制SQL语句格式。
-
2.2.3.1、默认配置
<many-to-one name="customer" cascade="save-update" column="lkm_cust_id" class="com.hibernate.domain.Customer" />
Customer.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 建立类与表的映射 --> <class name="com.hibernate.domain.Customer" table="cst_customer" > <!-- 建立类中的属性与表中的主键对应 --> <id name="cust_id" column="cust_id"> <generator class="native"></generator> </id> <!-- 建立类中的普通属性与表中的字段对应 --> <property name="cust_name" column="cust_name"></property> <property name="cust_source" column="cust_source"></property> <property name="cust_industry" column="cust_industry"></property> <property name="cust_level" column="cust_level"></property> <property name="cust_phone" column="cust_phone"></property> <property name="cust_mobile" column="cust_mobile"></property> <!-- 配置一对多的映射：放置的多的一方的集合 --> <!-- set标签 ： * name ：多的一方的对象集合的属性名称。 * cascade：级联 * inverse：放弃外键维护权。 --> <set name="linkMans" > <!--key标签 * column：多的一方的外键的名称。 --> <key column="lkm_cust_id" /> <!-- one-to-many标签 * class :多的一方的类的全路径 --> <one-to-many class="com.hibernate.domain.LinkMan" /> </set> </class> </hibernate-mapping>
@Test public void demo5() { Session session = HibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); LinkMan linkMan = session.get(LinkMan.class, 1l); System.out.println(linkMan.getCustomer().getCust_name());//此处设置断点 transaction.commit(); }
执行到断点前结果：
Hibernate: select linkman0_.lkm_id as lkm_id1_1_0_, linkman0_.lkm_name as lkm_name2_1_0_, linkman0_.lkm_gender as lkm_gend3_1_0_, linkman0_.lkm_phone as lkm_phon4_1_0_, linkman0_.lkm_mobile as lkm_mobi5_1_0_, linkman0_.lkm_email as lkm_emai6_1_0_, linkman0_.lkm_qq as lkm_qq7_1_0_, linkman0_.lkm_position as lkm_posi8_1_0_, linkman0_.lkm_memo as lkm_memo9_1_0_, linkman0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkman0_ where linkman0_.lkm_id=?
执行到断点后结果：
Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? lisi
2.2.3.2、fetch="select" lazy="proxy"
<many-to-one name="customer" fetch="select" lazy="proxy" cascade="save-update" column="lkm_cust_id" class="com.hibernate.domain.Customer" />
执行到断点前结果：
Hibernate: select linkman0_.lkm_id as lkm_id1_1_0_, linkman0_.lkm_name as lkm_name2_1_0_, linkman0_.lkm_gender as lkm_gend3_1_0_, linkman0_.lkm_phone as lkm_phon4_1_0_, linkman0_.lkm_mobile as lkm_mobi5_1_0_, linkman0_.lkm_email as lkm_emai6_1_0_, linkman0_.lkm_qq as lkm_qq7_1_0_, linkman0_.lkm_position as lkm_posi8_1_0_, linkman0_.lkm_memo as lkm_memo9_1_0_, linkman0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkman0_ where linkman0_.lkm_id=?
执行到断点后结果：
Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? lisi
2.2.3.2.1、fetch="select" lazy="proxy" 、关联对象的hbm.xml中<class>上的lazy=“false”
<class name="com.hibernate.domain.Customer" table="cst_customer" lazy="false" >
执行到断点前结果：
Hibernate: select linkman0_.lkm_id as lkm_id1_1_0_, linkman0_.lkm_name as lkm_name2_1_0_, linkman0_.lkm_gender as lkm_gend3_1_0_, linkman0_.lkm_phone as lkm_phon4_1_0_, linkman0_.lkm_mobile as lkm_mobi5_1_0_, linkman0_.lkm_email as lkm_emai6_1_0_, linkman0_.lkm_qq as lkm_qq7_1_0_, linkman0_.lkm_position as lkm_posi8_1_0_, linkman0_.lkm_memo as lkm_memo9_1_0_, linkman0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkman0_ where linkman0_.lkm_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?
执行到断点后结果：lisi
2.2.3.3、fetch="select" lazy="false"
<many-to-one name="customer" fetch="select" lazy="false" cascade="save-update" column="lkm_cust_id" class="com.hibernate.domain.Customer" />
执行到断点前结果：
Hibernate: select linkman0_.lkm_id as lkm_id1_1_0_, linkman0_.lkm_name as lkm_name2_1_0_, linkman0_.lkm_gender as lkm_gend3_1_0_, linkman0_.lkm_phone as lkm_phon4_1_0_, linkman0_.lkm_mobile as lkm_mobi5_1_0_, linkman0_.lkm_email as lkm_emai6_1_0_, linkman0_.lkm_qq as lkm_qq7_1_0_, linkman0_.lkm_position as lkm_posi8_1_0_, linkman0_.lkm_memo as lkm_memo9_1_0_, linkman0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkman0_ where linkman0_.lkm_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?
执行到断点后结果：lisi
2.2.3.4、fetch="join" lazy=失效
<many-to-one name="customer" fetch="join" cascade="save-update" column="lkm_cust_id" class="com.hibernate.domain.Customer" />
执行到断点前结果：
Hibernate: select linkman0_.lkm_id as lkm_id1_1_0_, linkman0_.lkm_name as lkm_name2_1_0_, linkman0_.lkm_gender as lkm_gend3_1_0_, linkman0_.lkm_phone as lkm_phon4_1_0_, linkman0_.lkm_mobile as lkm_mobi5_1_0_, linkman0_.lkm_email as lkm_emai6_1_0_, linkman0_.lkm_qq as lkm_qq7_1_0_, linkman0_.lkm_position as lkm_posi8_1_0_, linkman0_.lkm_memo as lkm_memo9_1_0_, linkman0_.lkm_cust_id as lkm_cus10_1_0_, customer1_.cust_id as cust_id1_0_1_, customer1_.cust_name as cust_nam2_0_1_, customer1_.cust_source as cust_sou3_0_1_, customer1_.cust_industry as cust_ind4_0_1_, customer1_.cust_level as cust_lev5_0_1_, customer1_.cust_phone as cust_pho6_0_1_, customer1_.cust_mobile as cust_mob7_0_1_ from cst_linkman linkman0_ left outer join cst_customer customer1_ on linkman0_.lkm_cust_id=customer1_.cust_id where linkman0_.lkm_id=?
执行到断点后结果：lisi
③、批量抓取（batch-size）
通过查询语句一次查询多条记录，通过配置batch-size的值确定一次查询多少条记录（都是在一的一方的hbm.xml配置）
1、通过客户获取联系人（需要配置set节点上batch-size,batch-size默认值为1）
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 建立类与表的映射 --> <class name="com.hibernate.domain.Customer" table="cst_customer"> <!-- 建立类中的属性与表中的主键对应 --> <id name="cust_id" column="cust_id"> <generator class="native"></generator> </id> <!-- 建立类中的普通属性与表中的字段对应 --> <property name="cust_name" column="cust_name"></property> <property name="cust_source" column="cust_source"></property> <property name="cust_industry" column="cust_industry"></property> <property name="cust_level" column="cust_level"></property> <property name="cust_phone" column="cust_phone"></property> <property name="cust_mobile" column="cust_mobile"></property> <!-- 配置一对多的映射：放置的多的一方的集合 --> <!-- set标签 ： * name ：多的一方的对象集合的属性名称。 * cascade：级联 * inverse：放弃外键维护权。 --> <set name="linkMans" > <!--key标签 * column：多的一方的外键的名称。 --> <key column="lkm_cust_id" /> <!-- one-to-many标签 * class :多的一方的类的全路径 --> <one-to-many class="com.hibernate.domain.LinkMan" /> </set> </class> </hibernate-mapping>
@Test public void demo5() { Session session = HibernateUtils.getCurrentSession(); Transaction transaction = session.beginTransaction(); List<Customer> list = session.createQuery("from Customer").list(); for (Customer customer : list) { System.out.println(customer.getCust_name()); for (LinkMan linkMan : customer.getLinkMans()) { //设置断点 System.out.println(linkMan.getLkm_name()); } } transaction.commit(); }
执行到断点前结果：
Hibernate: select customer0_.cust_id as cust_id1_0_, customer0_.cust_name as cust_nam2_0_, customer0_.cust_source as cust_sou3_0_, customer0_.cust_industry as cust_ind4_0_, customer0_.cust_level as cust_lev5_0_, customer0_.cust_phone as cust_pho6_0_, customer0_.cust_mobile as cust_mob7_0_ from cst_customer customer0_ lisi
执行到断点后结果：
Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=? Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_0_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_name as lkm_name2_1_1_, linkmans0_.lkm_gender as lkm_gend3_1_1_, linkmans0_.lkm_phone as lkm_phon4_1_1_, linkmans0_.lkm_mobile as lkm_mobi5_1_1_, linkmans0_.lkm_email as lkm_emai6_1_1_, linkmans0_.lkm_qq as lkm_qq7_1_1_, linkmans0_.lkm_position as lkm_posi8_1_1_, linkmans0_.lkm_memo as lkm_memo9_1_1_, linkmans0_.lkm_cust_id as lkm_cus10_1_1_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id=?
2、通过客户获取联系人（需要配置set节点上batch-size=“3”）
<set name="linkMans" batch-size="3" >
执行到断点前结果：
Hibernate: select customer0_.cust_id as cust_id1_0_, customer0_.cust_name as cust_nam2_0_, customer0_.cust_source as cust_sou3_0_, customer0_.cust_industry as cust_ind4_0_, customer0_.cust_level as cust_lev5_0_, customer0_.cust_phone as cust_pho6_0_, customer0_.cust_mobile as cust_mob7_0_ from cst_customer customer0_ lisi
执行到断点后结果：
Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_1_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_name as lkm_name2_1_0_, linkmans0_.lkm_gender as lkm_gend3_1_0_, linkmans0_.lkm_phone as lkm_phon4_1_0_, linkmans0_.lkm_mobile as lkm_mobi5_1_0_, linkmans0_.lkm_email as lkm_emai6_1_0_, linkmans0_.lkm_qq as lkm_qq7_1_0_, linkmans0_.lkm_position as lkm_posi8_1_0_, linkmans0_.lkm_memo as lkm_memo9_1_0_, linkmans0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id in ( ?, ?, ? ) Hibernate: select linkmans0_.lkm_cust_id as lkm_cus10_1_1_, linkmans0_.lkm_id as lkm_id1_1_1_, linkmans0_.lkm_id as lkm_id1_1_0_, linkmans0_.lkm_name as lkm_name2_1_0_, linkmans0_.lkm_gender as lkm_gend3_1_0_, linkmans0_.lkm_phone as lkm_phon4_1_0_, linkmans0_.lkm_mobile as lkm_mobi5_1_0_, linkmans0_.lkm_email as lkm_emai6_1_0_, linkmans0_.lkm_qq as lkm_qq7_1_0_, linkmans0_.lkm_position as lkm_posi8_1_0_, linkmans0_.lkm_memo as lkm_memo9_1_0_, linkmans0_.lkm_cust_id as lkm_cus10_1_0_ from cst_linkman linkmans0_ where linkmans0_.lkm_cust_id in ( ?, ?, ? )
配置batch-size后，每次查询条件个数为batch-size值，如果查询条件个数小于batch-size的值，那就查询一次，否则就会查询batch-size值的倍数次
3、通过联系人查找客户
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 建立类与表的映射 --> <class name="com.hibernate.domain.Customer" table="cst_customer"> <!-- 建立类中的属性与表中的主键对应 --> <id name="cust_id" column="cust_id"> <generator class="native"></generator> </id> <!-- 建立类中的普通属性与表中的字段对应 --> <property name="cust_name" column="cust_name"></property> <property name="cust_source" column="cust_source"></property> <property name="cust_industry" column="cust_industry"></property> <property name="cust_level" column="cust_level"></property> <property name="cust_phone" column="cust_phone"></property> <property name="cust_mobile" column="cust_mobile"></property> <!-- 配置一对多的映射：放置的多的一方的集合 --> <!-- set标签 ： * name ：多的一方的对象集合的属性名称。 * cascade：级联 * inverse：放弃外键维护权。 --> <set name="linkMans" > <!--key标签 * column：多的一方的外键的名称。 --> <key column="lkm_cust_id" /> <!-- one-to-many标签 * class :多的一方的类的全路径 --> <one-to-many class="com.hibernate.domain.LinkMan" /> </set> </class> </hibernate-mapping>
结果：Customer被查询多次
Hibernate: select linkman0_.lkm_id as lkm_id1_1_, linkman0_.lkm_name as lkm_name2_1_, linkman0_.lkm_gender as lkm_gend3_1_, linkman0_.lkm_phone as lkm_phon4_1_, linkman0_.lkm_mobile as lkm_mobi5_1_, linkman0_.lkm_email as lkm_emai6_1_, linkman0_.lkm_qq as lkm_qq7_1_, linkman0_.lkm_position as lkm_posi8_1_, linkman0_.lkm_memo as lkm_memo9_1_, linkman0_.lkm_cust_id as lkm_cus10_1_ from cst_linkman linkman0_ Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=? Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id=?
3.1、修改<class> 节点上batch-size属性值
<class name="com.hibernate.domain.Customer" table="cst_customer" batch-size="6">
结果：Customer被查询一次
Hibernate: select linkman0_.lkm_id as lkm_id1_1_, linkman0_.lkm_name as lkm_name2_1_, linkman0_.lkm_gender as lkm_gend3_1_, linkman0_.lkm_phone as lkm_phon4_1_, linkman0_.lkm_mobile as lkm_mobi5_1_, linkman0_.lkm_email as lkm_emai6_1_, linkman0_.lkm_qq as lkm_qq7_1_, linkman0_.lkm_position as lkm_posi8_1_, linkman0_.lkm_memo as lkm_memo9_1_, linkman0_.lkm_cust_id as lkm_cus10_1_ from cst_linkman linkman0_ Hibernate: select customer0_.cust_id as cust_id1_0_0_, customer0_.cust_name as cust_nam2_0_0_, customer0_.cust_source as cust_sou3_0_0_, customer0_.cust_industry as cust_ind4_0_0_, customer0_.cust_level as cust_lev5_0_0_, customer0_.cust_phone as cust_pho6_0_0_, customer0_.cust_mobile as cust_mob7_0_0_ from cst_customer customer0_ where customer0_.cust_id in ( ?, ?, ?, ?, ?, ? )
