hibernate之一对多

最新推荐文章于 2025-12-18 02:00:00 发布

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本文通过省和市的生活实例，详细解释了一对多的关系，并使用Hibernate进行了一对多关系的代码演示，涉及省实体类province和市实体类city的创建。

1.思路重要，首先我们可以结合生活实例，比如省和市的案例：每个地方只有一个省，但是一个省不止一个市。这就是一对多的案例

所以今天Tiny就结合省市的这个案例跟大家演示一下一对多。

2.代码演示：

<1>

省的实体类province

package com.zking.entity;

import java.util.HashSet;
import java.util.Set;

public class Province {
	private int pid;
	private String pname;
	
	private Set<City> cities=new HashSet<City>();
	
	public Set<City> getCities() {
		return cities;
	}
	public void setCities(Set<City> cities) {
		this.cities = cities;
	}
	public Province() {
		super();
	}
	public Province(String pname) {
		super();
		this.pname = pname;
	}
	public int getPid() {
		return pid;
	}
	public void setPid(int pid) {
		this.pid = pid;
	}
	public String getPname() {
		return pname;
	}
	public void setPname(String pname) {
		this.pname = pname;
	}
}

province.hbm.xml

package com.zking.entity;

import java.util.HashSet;
import java.util.Set;

public class Province {
	private int pid;
	private String pname;
	
	private Set<City> cities=new HashSet<City>();
	
	public Set<City> getCities() {
		return cities;
	}
	public void setCities(Set<City> cities) {
		this.cities = cities;
	}
	public Province() {
		super();
	}
	public Province(String pname) {
		super();
		this.pname = pname;
	}
	public int getPid() {
		return pid;
	}
	public void setPid(int pid) {
		this.pid = pid;
	}
	public String getPname() {
		return pname;
	}
	public void setPname(String pname) {
		this.pname = pname;
	}
}

<2>

city市的实体类

package com.zking.entity;

public class City {
	private int cid;
	private String cname;
//	private int pid;
	
	private Province province;
	
	public Province getProvince() {
		return province;
	}
	public void setProvince(Province province) {
		this.province = province;
	}
	public City() {
		super();
		// TODO Auto-generated constructor stub
	}
	public City(String cname) {
		super();
		this.cname = cname;
	}
	public int getCid() {
		return cid;
	}
	public void setCid(int cid) {
		this.cid = cid;
	}
	public String getCname() {
		return cname;
	}
	public void setCname(String cname) {
		this.cname = cname;
	}
//	public int getPid() {
//		return pid;
//	}
//	public void setPid(int pid) {
//		this.pid = pid;
//	}
}

city.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">
<!-- Generated 2017-8-22 15:14:11 by Hibernate Tools 3.5.0.Final -->
<hibernate-mapping>
    <class name="com.zking.entity.City" table="CITY">
        <id name="cid" type="int">
            <column name="CID" />
            <generator class="native" />
        </id>
        <property name="cname" type="java.lang.String">
            <column name="CNAME" />
        </property>
       <!--  <property name="pid" type="int">
            <column name="PID" />
        </property> -->
        <many-to-one name="province" class="com.zking.entity.Province" column="pid"></many-to-one>
    </class>
</hibernate-mapping>

test类测试：

package com.zking.test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.zking.entity.Card;
import com.zking.entity.City;
import com.zking.entity.Province;
import com.zking.entity.User;

public class TestOneToMany {
	private SessionFactory sessionFactory;
	private Session session;
	private Transaction transaction;


	@Before
	public void before(){
		Configuration configuration=new Configuration

().configure();
		sessionFactory = configuration.buildSessionFactory

();
		session = sessionFactory.openSession();
		transaction = session.beginTransaction();
	}
	@After
	public void after(){
		transaction.commit();
		session.close();
		sessionFactory.close();
	}
	//添加
	public void testAdd(){
		Province province=new Province("湖南省");
		
		City city1=new City("长沙市");
		City city2=new City("娄底市");
		City city3=new City("其他市");
		
		province.getCities().add(city1);
		province.getCities().add(city2);
		province.getCities().add(city3);
		
		city1.setProvince(province);
		city2.setProvince(province);
		city3.setProvince(province);
		
		session.save(province);
	}
}

在此tiny只给大家演示了增加的方法，删除查询修改都差不多，就不在过多演示了