hibernate单向set-based关联

person有多个event，一个event有多个person参与，明显的多对多关联，这篇只建立简单的one2many关联，下节继续many2many关联。

com.hb.jo包下实体类Person、Event及相应的映射描述文件。我们建立person-event的一对多关联,通过一个中间表使用两个表id关联。

 

hibernate.cfg.xml

 

 

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>
		<!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://127.0.0.1:3306/htest</property>
        <property name="connection.username">root</property>
        <property name="connection.password">123456</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">update</property>

        <mapping resource="com/hb/jo/event.hbm.xml"/>
		<mapping resource="com/hb/jo/person.hbm.xml"/> 
	</session-factory>
	
</hibernate-configuration>

 

 

Person.java

 

package com.hb.jo;

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

public class Person {

	private long id;
	private String name;
	private int age;
	private Date birthday;
	
	private Set<Event> events = new HashSet<Event>();
	private Set<String> mails = new HashSet<String>();
	
	
	
	public Set<String> getMails() {
		return mails;
	}
	public void setMails(Set<String> mails) {
		this.mails = mails;
	}
	public Set<Event> getEvents() {
		return events;
	}
	public void setEvents(Set<Event> events) {
		this.events = events;
	}
	public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public Date getBirthday() {
		return birthday;
	}
	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}
	
}

Event.java

 

 

package com.hb.jo;

import java.util.Date;

public class Event {

	private long id;
	private String title;
	private Date date;
	

	//因为hibernate通过java的反射机制创建对象，所以必须提供无参的构造
	public Event()
	{
		
	}
	
	public long getId() {
		return id;
	}

	public void setId(long id) {
		this.id = id;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}


	public Date getDate() {
		return date;
	}

	public void setDate(Date date) {
		this.date = date;
	}
}	
	

 

person.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">

<hibernate-mapping>
	<class name="com.hb.jo.Person" table="Person">
		<id name="id" column="person_id">
			<generator class="native"></generator>
		</id>
		<property name="name"></property>
		<property name="age"></property>
		<property name="birthday" type="timestamp"></property>
		<set name="events" table="Person_Events">
			<key column="person_id"></key>
			<many-to-many column="event_id" class="com.hb.jo.Event"></many-to-many>
		</set>
		<set name="mails" table="Person_Mail">
			<key column="person_id"></key>
			<element column="person_mail" type="string"></element>
		</set>
	</class>
</hibernate-mapping>

 event.hmb.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">

<hibernate-mapping>
	<class name="com.hb.jo.Event" table="Events">
		<id name="id" column="event_id">
			<generator class="native"></generator>
		</id>
		<property name="date" type="timestamp" column="Date"></property>
		<property name="title" column="Title"></property>
	</class>
</hibernate-mapping>