使用XML的Hibernate一对一示例 Hibernate一对一|Hibernate

有两种方法可以在Hibernate模式下执行一对一的映射：

通过多对一元素（使用unique =“ true”属性）
一对一要素

在这里, 我们将通过一对一元素执行一对一映射。在这种情况下, 不会在主表中创建任何外键。
在此示例中, 一个雇员可以有一个地址, 而一个地址仅属于一个雇员。在这里, 我们使用双向关联。让我们看一下持久化类。
1）一对一映射的持久类
有两个持久性类Employee.java和Address.java。雇员类包含地址类引用, 反之亦然。
Employee.java

package com.srcmini; public class Employee { private int employeeId; private String name, email; private Address address; //setters and getters }

Address.java

package com.srcmini; public class Address { private int addressId; private String addressLine1, city, state, country; private int pincode; private Employee employee; //setters and getters }

2）持久类的映射文件
这两个映射文件是employee.hbm.xml和address.hbm.xml。
employee.hbm.xml 在此映射文件中, 我们在两个映射文件中都使用了一对一元素来进行一对一映射。

< ?xml version='1.0' encoding='UTF-8'?> < !DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 5.3//EN" "http://hibernate.sourceforge.net/hibernate-mapping-5.3.dtd"> < hibernate-mapping> < class name="com.srcmini.Employee" table="emp212"> < id name="employeeId"> < generator class="increment"> < /generator> < /id> < property name="name"> < /property> < property name="email"> < /property> < one-to-one name="address" cascade="all"> < /one-to-one> < /class> < /hibernate-mapping>

address.hbm.xml 这是Address类的简单映射文件。但是重要的是生成器类。在这里, 我们使用依赖于Employee类主键的外部生成器类。

< ?xml version='1.0' encoding='UTF-8'?> < !DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 5.3//EN" "http://hibernate.sourceforge.net/hibernate-mapping-5.3.dtd"> < hibernate-mapping> < class name="com.srcmini.Address" table="address212"> < id name="addressId"> < generator class="foreign"> < param name="property"> employee< /param> < /generator> < /id> < property name="addressLine1"> < /property> < property name="city"> < /property> < property name="state"> < /property> < property name="country"> < /property> < property name="pincode"> < /property> < one-to-one name="employee"> < /one-to-one> < /class> < /hibernate-mapping>

3）配置文件
【使用XML的Hibernate一对一示例】该文件包含有关数据库和映射文件的信息。
hibernate.cfg.xml

< ?xml version='1.0' encoding='UTF-8'?> < !DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 5.3//EN" "http://hibernate.sourceforge.net/hibernate-configuration-5.3.dtd"> < hibernate-configuration> < session-factory> < property name="hbm2ddl.auto"> update< /property> < property name="dialect"> org.hibernate.dialect.Oracle9Dialect< /property> < property name="connection.url"> jdbc:oracle:thin:@localhost:1521:xe< /property> < property name="connection.username"> system< /property> < property name="connection.password"> jtp< /property> < property name="connection.driver_class"> oracle.jdbc.driver.OracleDriver< /property> < mapping resource="employee.hbm.xml"/> < mapping resource="address.hbm.xml"/> < /session-factory> < /hibernate-configuration>

4）用于存储和获取数据的用户类
Store.java

package com.srcmini; import org.hibernate.*; import org.hibernate.boot.Metadata; import org.hibernate.boot.MetadataSources; import org.hibernate.boot.registry.StandardServiceRegistry; import org.hibernate.boot.registry.StandardServiceRegistryBuilder; public class Store { public static void main(String[] args) { StandardServiceRegistry ssr=new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build(); Metadata meta=new MetadataSources(ssr).getMetadataBuilder().build(); SessionFactory factory=meta.getSessionFactoryBuilder().build(); Session session=factory.openSession(); Transaction t=session.beginTransaction(); Employee e1=new Employee(); e1.setName("Ravi Malik"); e1.setEmail("ravi@gmail.com"); Address address1=new Address(); address1.setAddressLine1("G-21, Lohia nagar"); address1.setCity("Ghaziabad"); address1.setState("UP"); address1.setCountry("India"); address1.setPincode(201301); e1.setAddress(address1); address1.setEmployee(e1); session.persist(e1); t.commit(); session.close(); System.out.println("success"); } }

输出量

文章图片

文章图片
Fetch.java

package com.srcmini; import java.util.*; import javax.persistence.TypedQuery; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.boot.Metadata; import org.hibernate.boot.MetadataSources; import org.hibernate.boot.registry.StandardServiceRegistry; import org.hibernate.boot.registry.StandardServiceRegistryBuilder; public class Fetch { public static void main(String[] args) { StandardServiceRegistry ssr=new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build(); Metadata meta=new MetadataSources(ssr).getMetadataBuilder().build(); SessionFactory factory=meta.getSessionFactoryBuilder().build(); Session session=factory.openSession(); TypedQuery query=session.createQuery("from Employee e"); List< Employee> list=query.getResultList(); Iterator< Employee> itr=list.iterator(); while(itr.hasNext()){ Employee emp=itr.next(); System.out.println(emp.getEmployeeId()+" "+emp.getName()+" "+emp.getEmail()); Address address=emp.getAddress(); System.out.println(address.getAddressLine1()+" "+address.getCity()+" "+ address.getState()+" "+address.getCountry()+" "+address.getPincode()); }session.close(); System.out.println("success"); } }

输出量