使用XML Hibernate多对一映射

本文概述

• 1）一对一映射的持久类
• 2）持久类的映射文件
• 3）配置文件
• 4）用于存储和获取数据的用户类

在多对一映射中, 各种属性只能称为一个属性。

在此示例中, 每个员工只有一个公司地址, 而一个地址属于许多员工。在这里, 我们将使用XML执行多对一映射。

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

<?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="emp22">  
          <id name="employeeId">  
          <generator class="increment"></generator>  
          </id>  
          <property name="name"></property>  
          <property name="email"></property>  
            
          <many-to-one name="address" cascade="all"></many-to-one>  
          </class>  
            
          </hibernate-mapping>

address.hbm.xml

<?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="address22">  
          <id name="addressId">  
          <generator class="increment"></generator>  
          </id>  
          <property name="addressLine1"></property>  
          <property name="city"></property>  
          <property name="state"></property>  
          <property name="country"></property>  
          <property name="pincode"></property>  
          </class>  
          </hibernate-mapping>

3）配置文件

该文件包含有关数据库和映射文件的信息。

<?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");  
    
    Employee e2=new Employee();
    e2.setName("Anuj Verma");
    e2.setEmail("anuj@gmail.com");
      
    Address address1=new Address();  
    address1.setAddressLine1("G-13, Sector 3");  
    address1.setCity("Noida");  
    address1.setState("UP");  
    address1.setCountry("India");  
    address1.setPincode(201301);  
      
    e1.setAddress(address1);  
    e2.setAddress(address1);

    session.persist(e1);  
    session.persist(e2);
    t.commit();  
      
    session.close();  
    System.out.println("success");  
}  
}

输出量

Fetch.java

package com.srcmini;  
import java.util.Iterator;  
import java.util.List;

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

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