首页 > 代码库 > [原创]java WEB学习笔记85：Hibernate学习之路-- -映射 一对一关系 ，基于主键方式实现
[原创]java WEB学习笔记85：Hibernate学习之路-- -映射 一对一关系 ，基于主键方式实现
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1.基于主键映射的 1-1
1）基于主键的映射策略:指一端的主键生成器使用 foreign 策略,表明根据”对方”的主键来生成自己的主键，自己并不能独立生成主键. <param> 子元素指定使用当前持久化类的哪个属性作为 “对方”
1 <hibernate-mapping package="com.jason.hibernate.entities.primary.one2one"> 2 3 <class name="Department" table="DEPARTMENT"> 4 5 <id name="deptId" type="java.lang.Integer"> 6 <column name="DEPT_ID" /> 7 <generator class="foreign"> 8 <param name="property">mgr</param> 9 </generator>10 </id>11 12 <property name="deptName" type="java.lang.String">13 <column name="DEPT_NAME" />14 </property>15 16 17 <one-to-one name="mgr" class="Manager" constrained="true"></one-to-one>18 19 20 </class>21 22 </hibernate-mapping>
2）采用foreign主键生成器策略的一端增加 one-to-one 元素映射关联属性，其one-to-one属性还应增加 constrained=“true” 属性；另一端增加one-to-one元素映射关联属性。
1 <hibernate-mapping package="com.jason.hibernate.entities.primary.one2one"> 2 <class name="Manager" table="MANAGER"> 3 4 <id name="mgrId" type="java.lang.Integer"> 5 <column name="MGR_ID" /> 6 <generator class="native" /> 7 </id> 8 9 <property name="mgrName" type="java.lang.String">10 <column name="MGR_NAME" />11 </property>12 13 <one-to-one name="dept" class="Department"></one-to-one>14 15 </class>16 17 </hibernate-mapping>
3）constrained(约束):指定为当前持久化类对应的数据库表的主键添加一个外键约束，引用被关联的对象(“对方”)所对应的数据库表主键
2.代码
Department
1 package com.jason.hibernate.entities.foreign.one2one; 2 3 public class Department { 4 private Integer deptId; 5 private String deptName; 6 7 private Manager mgr; 8 9 public Integer getDeptId() {10 return deptId;11 }12 13 public void setDeptId(Integer deptId) {14 this.deptId = deptId;15 }16 17 public String getDeptName() {18 return deptName;19 }20 21 public void setDeptName(String deptName) {22 this.deptName = deptName;23 }24 25 public Manager getMgr() {26 return mgr;27 }28 29 public void setMgr(Manager mgr) {30 this.mgr = mgr;31 }32 33 }
Manager
1 package com.jason.hibernate.entities.foreign.one2one; 2 3 public class Manager { 4 5 private Integer mgrId; 6 private String mgrName; 7 private Department dept; 8 9 public Integer getMgrId() {10 return mgrId;11 }12 13 public void setMgrId(Integer mgrId) {14 this.mgrId = mgrId;15 }16 17 public String getMgrName() {18 return mgrName;19 }20 21 public void setMgrName(String mgrName) {22 this.mgrName = mgrName;23 }24 25 public Department getDept() {26 return dept;27 }28 29 public void setDept(Department dept) {30 this.dept = dept;31 }32 33 }
Department.hbm.xml
1 <?xml version="1.0"?> 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 4 <!-- Generated 2016-10-5 22:31:35 by Hibernate Tools 3.4.0.CR1 --> 5 <hibernate-mapping package="com.jason.hibernate.entities.primary.one2one"> 6 7 <class name="Department" table="DEPARTMENT"> 8 9 <id name="deptId" type="java.lang.Integer">10 <column name="DEPT_ID" />11 <generator class="foreign">12 <param name="property">mgr</param>13 </generator>14 </id>15 16 <property name="deptName" type="java.lang.String">17 <column name="DEPT_NAME" />18 </property>19 20 21 <one-to-one name="mgr" class="Manager" constrained="true"></one-to-one>22 23 24 </class>25 26 </hibernate-mapping>
Manager.hbm.xml
1 <?xml version="1.0"?> 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 4 <!-- Generated 2016-10-5 22:31:35 by Hibernate Tools 3.4.0.CR1 --> 5 <hibernate-mapping package="com.jason.hibernate.entities.primary.one2one"> 6 <class name="Manager" table="MANAGER"> 7 8 <id name="mgrId" type="java.lang.Integer"> 9 <column name="MGR_ID" />10 <generator class="native" />11 </id>12 13 <property name="mgrName" type="java.lang.String">14 <column name="MGR_NAME" />15 </property>16 17 <one-to-one name="dept" class="Department"></one-to-one>18 19 </class>20 21 </hibernate-mapping>
hibernate.cfg.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-configuration PUBLIC 3 "-//Hibernate/Hibernate Configuration DTD 3.0//EN" 4 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> 5 <hibernate-configuration> 6 <session-factory> 7 <!-- hibernate 连接数据库的基本信息 --> 8 <property name="connection.username">root</property> 9 <property name="connection.password">zhangzhen</property>10 <property name="connection.driver_class">com.mysql.jdbc.Driver</property>11 <property name="connection.url">jdbc:mysql:///hibernate</property>12 13 14 <!-- 配置hibernate 的节本信息 -->15 <!-- hibernate 所使用的数据库方言 -->16 <!--<property name="dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>-->17 <property name="dialect">org.hibernate.dialect.MySQLDialect</property> 18 <!-- 执行操作时是否在控制台打印SQL -->19 <property name="show_sql">true</property>20 21 <!-- 是否都SQL 进行格式化 -->22 <property name="format_sql">true</property>23 24 25 <!-- 指定自动生成数据表的策略 -->26 <property name="hbm2ddl.auto">update</property>27 28 <!-- 设置hibernate 的事务隔离级别 -->29 <property name="connection.isolation">2</property>30 31 32 <!-- 配置c3p0 -->33 <property name="hibernate.c3p0.max_size">10</property>34 <property name="hibernate.c3p0.min_size">5</property>35 <property name="c3p0.acquire_increment">2</property>36 <property name="c3p0.idle_test_period">2000</property>37 <property name="c3p0.timeout">2000</property>38 <property name="c3p0.max_statements">10</property>39 40 41 <!-- 对于mysql 无效，对于oracle 有效 -->42 <!-- 设定JDBC 的Statement 读取数据的时候每次从数据库中取出的记录的条数 -->43 <property name="hibernate.jdbc.fetch_size">100</property>44 45 <!-- 设置数据库进行批量删除，批量更新和批量插入的时候的大小 -->46 <property name="hibernate.jdbc.batch_size">30</property>47 48 <!-- 指定关联的 .hbm.xml 文件 -->49 <!-- 50 <mapping resource="hibernate/helloworld/News.hbm.xml"/>51 <mapping resource="hibernate/helloworld/Worker.hbm.xml"/>52 53 <mapping resource="com/jason/hibernate/entities/n21/Customer.hbm.xml"/>54 <mapping resource="com/jason/hibernate/entities/n21/Order.hbm.xml"/>55 -->56 57 <mapping resource="com/jason/hibernate/entities/n21/both/Customer.hbm.xml"/> 58 <mapping resource="com/jason/hibernate/entities/n21/both/Order.hbm.xml"/> 59 60 61 <!-- 1-1 映射 -->62 <!-- 基于外键实现 -->63 <!-- <mapping resource="com/jason/hibernate/entities/foreign/one2one/Manager.hbm.xml"/>64 <mapping resource="com/jason/hibernate/entities/foreign/one2one/Department.hbm.xml"/>65 -->66 <!-- 基于主键实现 -->67 <mapping resource="com/jason/hibernate/entities/primary/one2one/Manager.hbm.xml"/>68 <mapping resource="com/jason/hibernate/entities/primary/one2one/Department.hbm.xml"/>69 70 71 </session-factory>72 73 </hibernate-configuration>
HibernateTest.java
1 package com.jason.hibernate.entities.foreign.one2one; 2 3 import hibernate.helloworld.News; 4 5 import java.util.Date; 6 7 import org.hibernate.Hibernate; 8 import org.hibernate.Session; 9 import org.hibernate.SessionFactory; 10 import org.hibernate.Transaction; 11 import org.hibernate.cfg.Configuration; 12 import org.hibernate.service.ServiceRegistry; 13 import org.hibernate.service.ServiceRegistryBuilder; 14 import org.junit.After; 15 import org.junit.Before; 16 import org.junit.Test; 17 18 public class HibernateTest { 19 20 private SessionFactory sessionFactory; 21 private Session session; 22 private Transaction transaction; 23 @Test 24 public void test() { 25 26 // 1. 创建一个SessionFatory 对象 27 SessionFactory sessionFactory = null; 28 29 // 1) 创建Configuration 对象：对应hibernate 的基本配置信息 和 对象关系映射信息 30 Configuration configuration = new Configuration().configure(); 31 32 // 2) 创建一个ServiceRegistry 对象：hibernate 4.x 新天添加的对象。 33 // hibernate 的任何配置 和 服务都需要在该对象中注册后才有效 34 ServiceRegistry serviceRegistry = new ServiceRegistryBuilder() 35 .applySettings(configuration.getProperties()) 36 .buildServiceRegistry(); 37 38 // sessionFactory = configuration.buildSessionFactory(); 39 sessionFactory = configuration.buildSessionFactory(serviceRegistry); 40 41 // 2. 创建一个session 对象 42 Session session = sessionFactory.openSession(); 43 44 // 3. 开启事物 45 Transaction transaction = session.beginTransaction(); 46 47 // 4.执行保存操作 48 News news = new News("java", "jason", new Date( 49 new java.util.Date().getTime())); 50 session.save(news); 51 52 // 5.提交事物 53 transaction.commit(); 54 // 6.关闭session 55 session.close(); 56 // 7.关闭SessionFactory 对象 57 sessionFactory.close(); 58 } 59 60 // 创建上述三个对象 61 @Before 62 public void init() { 63 Configuration configuration = new Configuration().configure(); 64 ServiceRegistry serviceRegistry = new ServiceRegistryBuilder() 65 .applySettings(configuration.getProperties()) 66 .buildServiceRegistry(); 67 68 sessionFactory = configuration.buildSessionFactory(serviceRegistry); 69 70 session = sessionFactory.openSession(); 71 72 transaction = session.beginTransaction(); 73 } 74 75 // 关闭上述三个对象 76 @After 77 public void destroy() { 78 transaction.commit(); 79 session.close(); 80 sessionFactory.close(); 81 } 82 83 84 @Test 85 public void testSave(){ 86 87 Department department = new Department(); 88 department.setDeptName("DEPT-BB"); 89 90 Manager manager = new Manager(); 91 manager.setMgrName("MGR-BB"); 92 93 94 //设定关联关系 95 department.setMgr(manager); 96 manager.setDept(department); 97 98 //保存 99 //建议先保存没有外键列的那个对象，这样会减少update 语句100 session.save(manager);101 session.save(department);102 103 104 }105 106 @Test107 public void testGet(){108 109 //1.默认情况下对关联属性使用懒加载110 Department dept = (Department) session.get(Department.class, 1);111 System.out.println(dept.getDeptName());112 113 114 //2.查询Manager 对象的连接条件应该是dept.manager_id = mgr.manager_id115 //而不因该是 manager0_.MGR_ID=department1_.DEPT_ID 116 Manager mgr = dept.getMgr();117 System.out.println(mgr);118 }119 120 121 @Test122 public void testGet2(){123 124 //在查询没有外键的实体对象，使用的是左外连接查询，一并查询出其关联的对象，并已经进行初始化125 Manager manager = (Manager) session.get(Manager.class, 1);126 System.out.println(manager);127 128 System.out.println(manager.getDept().getDeptName());129 130 }131 132 133 134 135 }
[原创]java WEB学习笔记85：Hibernate学习之路-- -映射 一对一关系 ，基于主键方式实现
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