Hibernate框架-05-01-单向一对多关联映射

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实体一对多关联

例如部门与职工之间的关系，就是一对多
购物网站，用户与订单之间关系就是一对多

第一种存储多个对象的类型是Set类型。

数据库一对多关联

Set属性方式实现一对多

保存时候会执行三次SQL语句，插入一，插入多，更新多的外键。
注意，在数据库这里，一对应的没有外键，是被外键的，但是多有外键，是主动外键别人的。
但是在Java代码这里是反过来的，一有多的引用。

项目结构

order.java

package com.hibernate.entity;

public class Order {
    
    

	private Integer id;
	private Double price;
	
	
	public Integer getId() {
    
    
		return id;
	}
	public void setId(Integer id) {
    
    
		this.id = id;
	}
	public Double getPrice() {
    
    
		return price;
	}
	public void setPrice(Double price) {
    
    
		this.price = price;
	}
	@Override
	public String toString() {
    
    
		return "Order [id=" + id + ", price=" + price + "]";
	}
	
	
}

user.java

package com.hibernate.entity;

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

public class User {
    
    

	private Integer id;
	private String userName;
	private String password;
	//域模型中用来表示从用户能够导航到订单数据（从用户到订单的一对多关联）
	//先初始化是为了放置空引用异常
	//Set类型无序，且不重复。
	//要求有顺序的话还是用
	private Set orderSet = new HashSet<>();
	
	public Integer getId() {
    
    
		return id;
	}
	public void setId(Integer id) {
    
    
		this.id = id;
	}
	public String getUserName() {
    
    
		return userName;
	}
	public void setUserName(String userName) {
    
    
		this.userName = userName;
	}
	public String getPassword() {
    
    
		return password;
	}
	public void setPassword(String password) {
    
    
		this.password = password;
	}
	@Override
	public String toString() {
    
    
		return "User [id=" + id + ", userName=" + userName + ", password=" + password + "]";
	}
	public Set getOrderSet() {
    
    
		return orderSet;
	}
	public void setOrderSet(Set orderSet) {
    
    
		this.orderSet = orderSet;
	}
	
	
}

order.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.hibernate.entity">
    <class name="Order" table="hibernate_05_01_orders">
        <id name="id" type="int" column="id">
            <generator class="identity"></generator>
        </id>
        <property name="price" column="price" ></property>
      
    </class>
</hibernate-mapping>

user.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.hibernate.entity">
    <class name="User" table="hibernate_05_01_user">
        <id name="id" type="int" column="id">
            <generator class="identity"/>
        </id>
        <property name="userName" type="java.lang.String" column="name"/>
        <property name="password" type="java.lang.String" column="password"/>
        
        <!-- 映射User与Order之间的一对多关系
        	set标签用来映射Set类型的属性(name)
        	key:指定外键字段名字(此名称是数据库库名称)
        	one-to-many表示一对多关系 -->
        	
        	<!-- 用户与订单这种情况不会产生创建用户也创建订单，
        	删除订单也不会删除用户，所以进选择delete -->
        <set name="orderSet" cascade="delete">
        	<key column="USER_ID"/>
        	<one-to-many class="Order"/>
        </set>
    </class>
</hibernate-mapping>

Test.java

package com.hibernate.ui;

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

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.hibernate.entity.Order;
import com.hibernate.entity.User;
import com.hibernate.util.HibernateUtil;

public class Test {
    
    

	public static void main(String[] args) {
    
    
		saveUserAndOrder();
		
//		addOrder();
		
//		getUserAndOrders();
		
//		deleteUser();
		
		HibernateUtil.closeSessionFactory();
	}
	
	//保存
	private static void saveUserAndOrder() {
    
    
		Session session = HibernateUtil.openSession();
		Transaction tx = session.beginTransaction();
		
		User u = new User();
		u.setUserName("李四");
		u.setPassword("77777");
		
		Order o = new Order();
		o.setPrice(300.0);
		
		//建立关联
		Set set = new HashSet();
		set.add(o);
		u.setOrderSet(set);
		
		session.save(u);
		session.save(o);
		
		tx.commit();
		session.close();
	}
	
	
	
	
	
	//给已经存在的用户添加新的订单
	private static void addOrder() {
    
    
		Session session = HibernateUtil.openSession();
		Transaction tx = session.beginTransaction();
		
		User u = session.get(User.class, new Integer(1));
		
		//新的订单对象
		Order o = new Order();
		o.setPrice(200.0);
		
		//建立关联
		u.getOrderSet().add(o);
		
		session.save(o);
		tx.commit();
		session.close();
	}
	
	
	//一对一关联式，查询用户也会查询订单
	//一对多时候查询用户仅是用户
	//检索用户数据，并通过用户导航到它所关联的订单
	private static void getUserAndOrders() {
    
    
		Session session = HibernateUtil.openSession();
		//一对多关联映射默认情况下查询用户时，不会连接订单表查询
		User u = session.get(User.class, new Integer(1));
		
		//通过上述用户对象导航到它关联的订单(映射关联关系的优势)
		//这个方法也会触发一次查询
		System.out.println(u.getOrderSet());
		
		session.close();
	}
	
	//由于配置了级联删除操作，所以删除用户时，会自动删除同用户关联的订单
	private static void deleteUser() {
    
    
		Session session = HibernateUtil.openSession();
		Transaction tx = session.beginTransaction();
		
		User u = session.get(User.class, new Integer(1));
		session.delete(u);
		
		tx.commit();
		session.close();
	}

}

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- 版本号，编码方式 -->

<!DOCTYPE 
hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" 
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<!-- 文档类型，指定了网址可以下载文档定义文件，以确定下面可以出现的标签与规则 -->

<hibernate-configuration><!-- 根元素，必须包含此元素 -->

	<session-factory>
	<!-- 每一个 property就是一个配置项 -->
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<!-- dialect是方言，表明用的是什么数据库方言  -->
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<!-- 数据库驱动类，指定类名 -->
		<!-- 下面是链接数据库的信息，和JDBC类似 -->
		<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate-database?useUicode=true&amp;characterEncoding=UTF-8</property>
		<!-- &amp  是转义字符，此处是转义分号所用-->
		<property name="hibernate.connection.username">root</property>
		<property name="hibernate.connection.password"></property>
		
		<!-- 上面5个配置项是必选的，下面两个是可选的，分别是打印sql语句与格式化sql语句，便于调试-->
		<property name="hibernate.show_sql">true</property>
		<property name="hibernate.format_sql">true</property>
		
		<!-- 设置映射文件，属性值是包名+文件名，注意格式变化，点变成了斜杠-->

		<mapping resource="com/hibernate/entity/Order.hbm.xml"/> 
		<mapping resource="com/hibernate/entity/User.hbm.xml"/> 

	</session-factory>
	
</hibernate-configuration>

User.MySql

orders.MySql

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List属性实现一对多关联

项目结构

order.java

package com.hibernate.entity;

public class Order {
    
    

	private Integer id;
	private Double price;
	
	
	public Integer getId() {
    
    
		return id;
	}
	public void setId(Integer id) {
    
    
		this.id = id;
	}
	public Double getPrice() {
    
    
		return price;
	}
	public void setPrice(Double price) {
    
    
		this.price = price;
	}
	@Override
	public String toString() {
    
    
		return "Order [id=" + id + ", price=" + price + "]";
	}
	
	
}

user.java

package com.hibernate.entity;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class User {
    
    

	private Integer id;
	private String userName;
	private String password;
	//域模型中用来表示从用户能够导航到订单数据（从用户到订单的一对多关联）
	//先初始化是为了防止空引用异常
	//Set类型无序，且不重复。
	//要求有顺序的话还是用
	private List orderList = new ArrayList<>();
	
	public Integer getId() {
    
    
		return id;
	}
	public void setId(Integer id) {
    
    
		this.id = id;
	}
	public String getUserName() {
    
    
		return userName;
	}
	public void setUserName(String userName) {
    
    
		this.userName = userName;
	}
	public String getPassword() {
    
    
		return password;
	}
	public void setPassword(String password) {
    
    
		this.password = password;
	}
	@Override
	public String toString() {
    
    
		return "User [id=" + id + ", userName=" + userName + ", password=" + password + "]";
	}
	public List getOrderList() {
    
    
		return orderList;
	}
	public void setOrderList(List orderList) {
    
    
		this.orderList = orderList;
	}

	
	
}

order.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.hibernate.entity">
    <class name="Order" table="hibernate_05_02_orders">
        <id name="id" type="int" column="id">
            <generator class="identity"></generator>
        </id>
        <property name="price" column="price" ></property>
      
    </class>
</hibernate-mapping>

user.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.hibernate.entity">
    <class name="User" table="hibernate_05_02_user">
        <id name="id" type="int" column="id">
            <generator class="identity"/>
        </id>
        <property name="userName" type="java.lang.String" column="name"/>
        <property name="password" type="java.lang.String" column="password"/>
        
        <!-- 映射User与Order之间的一对多关系
        	List标签用来映射List类型的属性(name)
        	key:指定外键字段名字(此名称是数据库库名称)
        	index=保存插入顺序的字段
        	one-to-many表示一对多关系 -->
        	
        <list name="orderList" cascade="delete">
        	<key column="USER_ID"/>
        	<index column="index11"/>
        	<one-to-many class="Order"/>
        </list>
    </class>
</hibernate-mapping>

Test.java

package com.hibernate.ui;

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

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.hibernate.entity.Order;
import com.hibernate.entity.User;
import com.hibernate.util.HibernateUtil;

public class Test {
    
    

	public static void main(String[] args) {
    
    
//		saveUserAndOrder();
		
		addOrder();
		
//		getUserAndOrders();
		
//		deleteUser();
		
		HibernateUtil.closeSessionFactory();
	}
	
	//保存
	private static void saveUserAndOrder() {
    
    
		Session session = HibernateUtil.openSession();
		Transaction tx = session.beginTransaction();
		
		User u = new User();
		u.setUserName("李四");
		u.setPassword("77777");
		
		Order o = new Order();
		o.setPrice(300.0);
		
		//建立关联
		u.getOrderList().add(o);
		
		session.save(u);
		session.save(o);
		
		tx.commit();
		session.close();
	}
	
	//给已经存在的用户添加新的订单
	private static void addOrder() {
    
    
		Session session = HibernateUtil.openSession();
		Transaction tx = session.beginTransaction();
		
		User u = session.get(User.class, new Integer(3));
		System.out.println(u.toString());
		
		//新的订单对象
		Order o = new Order();
		o.setPrice(100.0);
		
		//建立关联
		u.getOrderList().add(o);
		
		session.save(o);
		tx.commit();
		session.close();
	}
	
	//检索用户数据，并通过用户导航到它所关联的订单
	private static void getUserAndOrders() {
    
    
		Session session = HibernateUtil.openSession();
		//一对多关联映射默认情况下查询用户时，不会连接订单表查询
		User u = session.get(User.class, new Integer(109));
		
		//通过上述用户对象导航到它关联的订单(映射关联关系的优势)
		System.out.println(u.getOrderList());
		
		session.close();
	}
	
	//由于配置了级联删除操作，所以删除用户时，会自动删除同用户关联的订单
	private static void deleteUser() {
    
    
		Session session = HibernateUtil.openSession();
		Transaction tx = session.beginTransaction();
		
		User u = session.get(User.class, new Integer(109));
		session.delete(u);
		
		tx.commit();
		session.close();
	}
	
	

}

user.MySql

orders.MySql

Map属性配置方式

项目结构

user.java

package com.hibernate.entity;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class User {
    
    

	private Integer id;
	private String userName;
	private String password;
	//域模型中用来表示从用户能够导航到订单数据（从用户到订单的一对多关联）
	//key - value 类型
	private Map<String,Order> orderMap = new HashMap<>();
	
	public Integer getId() {
    
    
		return id;
	}
	public void setId(Integer id) {
    
    
		this.id = id;
	}
	public String getUserName() {
    
    
		return userName;
	}
	public void setUserName(String userName) {
    
    
		this.userName = userName;
	}
	public String getPassword() {
    
    
		return password;
	}
	public void setPassword(String password) {
    
    
		this.password = password;
	}
	@Override
	public String toString() {
    
    
		return "User [id=" + id + ", userName=" + userName + ", password=" + password + "]";
	}
	public Map<String,Order> getOrderMap() {
    
    
		return orderMap;
	}
	public void setOrderMap(Map<String,Order> orderMap) {
    
    
		this.orderMap = orderMap;
	}
	

	
	
}

user.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.hibernate.entity">
    <class name="User" table="hibernate_05_03_user">
        <id name="id" type="int" column="id">
            <generator class="identity"/>
        </id>
        <property name="userName" type="java.lang.String" column="name"/>
        <property name="password" type="java.lang.String" column="password"/>
        
        <!-- 映射User与Order之间的一对多关系
        	map用来映射Map类型的属性
        	key:指定外键字段名字
        	index:指定保存Map中key值的字段
        	one-to-many表示一对多关系 -->
        <map name="orderMap" cascade="delete">
        	<key column="USER_ID"/>
        	<index column="ORDER_KEY" type="string"></index>
        	<!-- string时hibernate定义的数据类型 -->
        	<one-to-many class="Order"/>
        </map>
    </class>
</hibernate-mapping>

MySql

其他配置同上面的Set方式一样。

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