1 Hibernate的查询方式
1.1 Hibernate的查询方式
- 在Hibernate中有提供了很多种的查询方式。 Hibernate一共提供了5种查询方式：
- OID查询。
- 对象导航查询。
- HQL查询。
- QBC查询。
- SQL查询。
1.2 OID查询
- OID检索：HIbernate根据对象的OID（主键）查询。例如：使用get或load方法查询对象。
1.3 对象导航查询
- Hibernate根据一个已经查询到的对象，获取其关联对象的一种查询方式。例如：先查询到了联系人的信息，然后通过联系人对象获取对应的客户信息。
1.4 HQL查询
- HQL：Hibernate查询语言，是一种面向对象的方式的查询语言，语法类似SQL。通过session.createQuery()，用于接收一个HQL进行查询的方式。
1.4.1 搭建环境并进行数据初始化
- Customer.java
package com.xuweiwei.hibernate;import java.util.HashSet;import java.util.Set;/** * 客户 * * @author 许威威 */public class Customer { ???/** ????* 客户编号(主键) ????*/ ???private Long id; ???/** ????* 客户名称(公司名称) ????*/ ???private String name; ???/** ????* 客户信息来源 ????*/ ???private String source; ???/** ????* 客户所属行业 ????*/ ???private String industry; ???/** ????* 客户级别 ????*/ ???private String level; ???/** ????* 固定电话 ????*/ ???private String phone; ???/** ????* 移动电话 ????*/ ???private String mobile; ???//一个客户有多个联系人 ???private Set<LinkMan> linkMans = new HashSet<>(); ???public Long getId() { ???????return id; ???} ???public void setId(Long id) { ???????this.id = id; ???} ???public String getName() { ???????return name; ???} ???public void setName(String name) { ???????this.name = name; ???} ???public String getSource() { ???????return source; ???} ???public void setSource(String source) { ???????this.source = source; ???} ???public String getIndustry() { ???????return industry; ???} ???public void setIndustry(String industry) { ???????this.industry = industry; ???} ???public String getLevel() { ???????return level; ???} ???public void setLevel(String level) { ???????this.level = level; ???} ???public String getPhone() { ???????return phone; ???} ???public void setPhone(String phone) { ???????this.phone = phone; ???} ???public String getMobile() { ???????return mobile; ???} ???public void setMobile(String mobile) { ???????this.mobile = mobile; ???} ???public Set<LinkMan> getLinkMans() { ???????return linkMans; ???} ???public void setLinkMans(Set<LinkMan> linkMans) { ???????this.linkMans = linkMans; ???}}- LinkMan.java
package com.xuweiwei.hibernate;/** * 联系人 * * @author 许威威 */public class LinkMan { ???/** ????* 主键 ????*/ ???private Long id; ???/** ????* 联系人姓名 ????*/ ???private String name; ???/** ????* 联系人性别 ????*/ ???private Character gender; ???/** ????* 联系人办公电话 ????*/ ???private String phone; ???/** ????* 联系人手机 ????*/ ???private String mobile; ???/** ????* 联系人邮箱 ????*/ ???private String email; ???/** ????* 联系人QQ ????*/ ???private String qq; ???/** ????* 联系人职位 ????*/ ???private String position; ???/** ????* 联系人备注 ????*/ ???private String memo; ???//一个联系人属于一个客户 ???private Customer customer; ???public Long getId() { ???????return id; ???} ???public void setId(Long id) { ???????this.id = id; ???} ???public String getName() { ???????return name; ???} ???public void setName(String name) { ???????this.name = name; ???} ???public Character getGender() { ???????return gender; ???} ???public void setGender(Character gender) { ???????this.gender = gender; ???} ???public String getPhone() { ???????return phone; ???} ???public void setPhone(String phone) { ???????this.phone = phone; ???} ???public String getMobile() { ???????return mobile; ???} ???public void setMobile(String mobile) { ???????this.mobile = mobile; ???} ???public String getEmail() { ???????return email; ???} ???public void setEmail(String email) { ???????this.email = email; ???} ???public String getQq() { ???????return qq; ???} ???public void setQq(String qq) { ???????this.qq = qq; ???} ???public String getPosition() { ???????return position; ???} ???public void setPosition(String position) { ???????this.position = position; ???} ???public String getMemo() { ???????return memo; ???} ???public void setMemo(String memo) { ???????this.memo = memo; ???} ???public Customer getCustomer() { ???????return customer; ???} ???public void setCustomer(Customer customer) { ???????this.customer = 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.xuweiwei.hibernate.Customer" table="customer"> ???????<!-- 建立类中的属性与表中的主键对应 --> ???????<id name="id" column="id"> ???????????<generator ></generator> ???????</id> ???????<!-- 建立类中的普通的属性和表的字段的对应 --> ???????<property name="name" column="name"/> ???????<property name="source" column="source"/> ???????<property name="industry" column="industry"/> ???????<property name="level" column="level"/> ???????<property name="phone" column="phone"/> ???????<property name="mobile" column="mobile"/> ???????<set name="linkMans"> ???????????<key column="customer_id"></key> ???????????<one-to-many /> ???????</set> ???</class></hibernate-mapping>
- LinkMan.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.xuweiwei.hibernate.LinkMan" table="linkMan"> ???????<!-- 建立类中的属性与表中的主键对应 --> ???????<id name="id" column="id"> ???????????<generator ></generator> ???????</id> ???????<!-- 建立类中的普通的属性和表的字段的对应 --> ???????<property name="name" column="name"/> ???????<property name="gender" column="gender"/> ???????<property name="phone" column="phone"/> ???????<property name="mobile" column="mobile"/> ???????<property name="email" column="email"/> ???????<property name="qq" column="qq"/> ???????<property name="position" column="position"/> ???????<property name="memo" column="memo"/> ???????<many-to-one name="customer" column="customer_id"/> ???</class></hibernate-mapping>
- hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE hibernate-configuration PUBLIC ???????"-//Hibernate/Hibernate Configuration DTD 3.0//EN" ???????"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"><hibernate-configuration> ???<session-factory> ???????<!-- 连接数据库的基本参数 --> ???????<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> ???????<property name="hibernate.connection.url">jdbc:mysql:///hibernate</property> ???????<property name="hibernate.connection.username">root</property> ???????<property name="hibernate.connection.password">123456</property> ???????<!-- 配置Hibernate的方言 --> ???????<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> ???????<!-- 可选配置================ --> ???????<!-- 打印SQL --> ???????<property name="hibernate.show_sql">true</property> ???????<!-- 格式化SQL --> ???????<property name="hibernate.format_sql">true</property> ???????<!-- 自动创建表 --> ???????<property name="hibernate.hbm2ddl.auto">update</property> ???????<!-- 加载映射文件 --> ???????<mapping resource="com/xuweiwei/hibernate/Customer.hbm.xml"/> ???????<mapping resource="com/xuweiwei/hibernate/LinkMan.hbm.xml"/> ???</session-factory></hibernate-configuration>
- log4j.properties
### direct log messages to stdout ###log4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.Target=System.errlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n### direct messages to file mylog.log ###log4j.appender.file=org.apache.log4j.FileAppenderlog4j.appender.file.File=c\:mylog.loglog4j.appender.file.layout=org.apache.log4j.PatternLayoutlog4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n### set log levels - for more verbose logging change ‘info‘ to ‘debug‘ #### error warn info debug tracelog4j.rootLogger= info, stdout- 初始化数据
???//初始化数据 ???@Test ???public void test() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Customer customer1 = new Customer(); ???????customer1.setName("张无忌"); ???????Customer customer2 = new Customer(); ???????customer2.setName("张三丰"); ???????for (int i = 0; i < 10; i++) { ???????????LinkMan linkMan = new LinkMan(); ???????????linkMan.setName("赵敏" + (i+1)); ???????????customer1.getLinkMans().add(linkMan); ???????????linkMan.setCustomer(customer1); ???????????session.save(linkMan); ???????} ???????for (int i = 0; i < 10; i++) { ???????????LinkMan linkMan = new LinkMan(); ???????????linkMan.setName("郭襄" + (i+1)); ???????????customer2.getLinkMans().add(linkMan); ???????????linkMan.setCustomer(customer2); ???????????session.save(linkMan); ???????} ???????session.save(customer1); ???????session.save(customer2); ???????transaction.commit(); ???????session.close(); ???}1.4.2 HQL的简单查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery(" from Customer "); ???????List<Customer> list = query.list(); ???????for (Customer customer : list) { ???????????System.out.println(customer); ???????} ???????transaction.commit(); ???????session.close(); ???}- 示例：别名查询
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery(" from Customer c"); ???????List<Customer> list = query.list(); ???????for (Customer customer : list) { ???????????System.out.println(customer); ???????} ???????transaction.commit(); ???????session.close(); ???} ???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery("select c from Customer c"); ???????List<Customer> list = query.list(); ???????for (Customer customer : list) { ???????????System.out.println(customer); ???????} ???????transaction.commit(); ???????session.close(); ???}1.4.3 HQL的排序查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????//默认情况下，是升序 ???????Query query = session.createQuery("select c from Customer c order by id"); ???????List<Customer> list = query.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????//默认情况下，是升序 ???????Query query = session.createQuery(" select c from Customer c order by c.id desc "); ???????List<Customer> list = query.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.4.4 条件查询
- 示例：按位置绑定：和JDBC一样，只不多Hibernate的位置是从0开始的。
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery(" select c from Customer c where c.id = ? "); ???????query.setParameter(0,1L); ???????List<Customer> list = query.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}- 示例：按名称绑定
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery(" select c from Customer c where c.id = :id "); ???????query.setParameter("id",1L); ???????List<Customer> list = query.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.4.5 HQL的投影查询
- 投影查询：查询某个对象的某个属性或部分属性。
- 示例：查询所有客户的名称
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery(" select c.name from Customer c ?"); ???????List<Object> list = query.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}- 示例：查询所有客户的编号和名称
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//SQL中支持*的写法，但是HQL不支持 ???????Query query = session.createQuery(" select c.id,c.name from Customer c ?"); ???????List<Object[]> list = query.list(); ???????for (Object[] objects : list) { ???????????System.out.println(Arrays.asList(objects)); ???????} ???????transaction.commit(); ???????session.close(); ???}1.4.5 HQL的分组统计查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????//根据姓名分组 ???????Query query = session.createQuery("select l.name,count(l.id) from LinkMan l group by l.name "); ???????List<Object[]> list = query.list(); ???????for (Object[] objects : list) { ???????????System.out.println(Arrays.asList(objects)); ???????} ???????transaction.commit(); ???????session.close(); ???}1.4.6 HQL的分页查询
- 示例：分页显示联系人
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Integer pageNo = 1; ???????Integer pageSize = 5; ???????Query query = session.createQuery(" from LinkMan ?"); ???????query.setFirstResult((pageNo - 1) * pageSize); ???????query.setMaxResults(pageSize); ???????List<LinkMan> list = query.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.4.7 多表查询
- HQL支持的多表查询有：交叉连接、内连接（显示内连接，隐式内连接，迫切内连接）、外连接（左外连接、右外连接、迫切左外连接）。
- 所谓的迫切连接，就是在join后面添加一个关键字fetch。目的是通知Hibernate将另一个对象的数据封装到该对象中。
- 示例：内连接
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Query query = session.createQuery(" from Customer c inner join c.linkMans "); ???????List<Object[]> list = query.list(); ???????for (Object[] objects : list) { ???????????System.out.println(Arrays.toString(objects)); ???????} ???????transaction.commit(); ???????session.close(); ???}- 示例：迫切内连接
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Query query = session.createQuery(" select distinct c from Customer c inner join fetch c.linkMans "); ???????List<Customer> list = query.list(); ???????list.forEach(System.out::println); ???????transaction.commit(); ???????session.close(); ???}1.5 QBC查询
- QBC：条件查询。是一种更加面向对象化的查询方式。
1.5.1 简单查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Criteria criteria = session.createCriteria(Customer.class); ???????List<Customer> list = criteria.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.5.2 排序查询
- 示例：根据id降序
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Criteria criteria = session.createCriteria(Customer.class); ???????List<Customer> list = criteria.addOrder(Order.desc("id")).list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.5.3 分页查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Integer pageNo = 1; ???????Integer pageSize = 5; ???????Criteria criteria = session.createCriteria(LinkMan.class); ???????criteria.setFirstResult((pageNo - 1) * pageSize); ???????criteria.setMaxResults(pageSize); ???????List<LinkMan> list = criteria.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.5.4 条件查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Criteria criteria = session.createCriteria(Customer.class); ???????criteria.add(Restrictions.like("name","张", MatchMode.ANYWHERE)); ???????List<Customer> list = criteria.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}1.5.5 统计查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????Criteria criteria = session.createCriteria(Customer.class); ???????criteria.setProjection(Projections.rowCount()); ???????Object o = criteria.uniqueResult(); ???????System.out.println(o); ???????transaction.commit(); ???????session.close(); ???}1.6 SQL查询
- 示例：
???@Test ???public void test1() { ???????Session session = HibernateUtil.getSession(); ???????Transaction transaction = session.beginTransaction(); ???????SQLQuery sqlQuery = session.createSQLQuery(" select * from customer ").addEntity(Customer.class); ???????List<Customer> list = sqlQuery.list(); ???????System.out.println(list); ???????transaction.commit(); ???????session.close(); ???}2 Hibernate的抓取策略
Hibernate四
原文地址：https://www.cnblogs.com/xuweiweiwoaini/p/9941179.html