hibernate一对一主键单向关联
2024-08-25 00:29:43
关联是类(类的实例)之间的关系,表示有意义和值得关注的连接。
本系列将介绍Hibernate中主要的几种关联映射
Hibernate一对一主键单向关联
Hibernate一对一主键双向关联
Hibernate一对一外键单向关联
Hibernate一对一外键双向关联
Hibernate多对一单向关联
Hibernate多对一双向关联
Hibernate多对多关联
代码都写有注释,主要包括(核心配置文件,实体映射文件,实体类,测试类,数据库)主要操作有增删改查。
本篇主要介绍Hibernate一对一主键单向关联:
hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- 配置数据库连接驱动类 --> <property name="connection.driver_class">com.mysql.jdbc.Driver</property> <!-- 配置数据库连接字符串 --> <property name="connection.url"><![CDATA[jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf8]]></property> <!-- 配置数据库连接用户名 --> <property name="connection.username">root</property> <!-- 配置数据库连接密码 --> <property name="connection.password">123456</property> <!-- 配置数据库方言 --> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <!-- 配置数据库表生成策略 --> <!--<property name="hibernate.hbm2ddl.auto">update</property> --> <!-- 配置是否打印显示SQL语句 --> <property name="show_sql">true</property> <!-- 配置是否格式化显示SQL语句 --> <property name="format_sql">true</property> <!-- 配置hibernate是否自动提交事务 --> <!--<property name="hibernate.connection.autocommit">true</property> --> <!-- 配置实体类对应的映射文件 --> <!-- 一对一主键单向关联 --> <mapping resource="com/great/entity3/People.hbm.xml"></mapping> <mapping resource="com/great/entity3/IdCard.hbm.xml"></mapping> </session-factory> </hibernate-configuration>
People.hbm.xml
<?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 package="com.great.entity3"> <!-- 配置实体类与数据库表的映射关系 --> <class name="com.great.entity3.People" table="people"> <!-- 配置主键映射关系 --> <id name="id" column="id" type="int"> <!-- 配置主键生成策略 --> <generator class="foreign"> <param name="property">idCard</param> </generator> </id> <!-- 配置属性和表字段映射关系 --> <property name="pName" column="pName" type="string"></property> <one-to-one name="idCard" constrained="true" cascade="all" /> </class> </hibernate-mapping>
IdCard.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.great.entity3"> <class name="IdCard" table="idcard"> <id name="id" column="id" type="int"> <generator class="native"> </generator> </id> <!-- 配置属性和表字段映射关系 --> <property name="CardCode" column="cardCode" type="string"></property> </class> </hibernate-mapping>
People.java
package com.great.entity3; public class People { // 一对一主键单向关联 private int id; private String pName; private IdCard idCard; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getpName() { return pName; } public void setpName(String pName) { this.pName = pName; } public IdCard getIdCard() { return idCard; } public void setIdCard(IdCard idCard) { this.idCard = idCard; } }
IdCard.java
package com.great.entity3; public class IdCard { private int id; private String cardCode; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getCardCode() { return CardCode; } public void setCardCode(String cardCode) { CardCode = cardCode; } }
TestOneToOneUniqueUn.java(测试类)
package com.great.test; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import org.junit.AfterClass; import org.junit.BeforeClass; import org.junit.Test; import com.great.entity3.IdCard; import com.great.entity3.People; public class TestOneToOneUniqueUnidirectional { static Session session; // 一对一单向主键关联 @BeforeClass public static void setUpBeforeClass() throws Exception { // 加载hibernate主配置文件 Configuration cfg = new Configuration().configure(); // 构建session工厂 SessionFactory sf = cfg.buildSessionFactory(); // 打开session session = sf.openSession(); } @AfterClass public static void tearDownAfterClass() throws Exception { // 关闭session,释放资源 session.close(); } // select1, 通过idCard查询people @Test public void testOneToOneSelect1() { People people = (People) session.get(People.class, 1); System.out.println("身份证号码:" + people.getIdCard().getCardCode()); System.out.println("姓名:" + people.getpName()); } // insert1,通过保存people保存数据 两条insert,先保存inCard,再保存people @Test public void testOneToOneSave1() { Transaction ts = session.beginTransaction(); IdCard idCard = new IdCard(); idCard.setCardCode("311487199505051234"); People people = new People(); people.setpName("墨樱22"); people.setIdCard(idCard); session.save(people); ts.commit(); } // delete1, 通过people删除数据 两条select,两条delete,先delete people,再delete idCard @Test public void testOneToOneDelete1() { Transaction ts = session.beginTransaction(); People people = (People) session.get(People.class, 15); session.delete(people); ts.commit(); } // update1,通过people更新数据 两条select,两条update,先update people,再update inCard @Test public void testOneToOneUpdate1() { Transaction ts = session.beginTransaction(); People people = (People) session.get(People.class, 4); people.setpName("张起灵"); people.getIdCard().setCardCode("888888"); session.update(people); ts.commit(); } }
数据库:
people表
两个字段id pName
idcard表
两个字段id cardCode
注意:在people表上建立外键关系。
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