本例以Windows, JDK1.8, MySQL5 为基础，演示使用Hibernate5以注解的方式完成多对多的双向关系映射。

在多对多的关联上,需求创建一个中间表,中间表用来连接两个多不多关系的表,等于在中间表中保存了两个表的映射关系.

多对多的表的关系

Model

分别创建Hero和HeroBook两个Model对象，在映射关系上，Hero和HeroBook存在多对多映射,以Hero作为主控方。

File : Hero.java

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package com.devnp.hibernate.association.mtm.model;

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

import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

@Entity
@Table(name = "HERO")
public class Hero {
	
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Basic(optional = false)
	@Column(name = "HERO_ID")
	private Long heroId ;
	
	@Column(name = "HERO_NAME")
	private String heroName ;
	
	@Column(name = "HERO_AGE")
	private Integer heroAge ;
	
	@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
	@JoinTable(name = "heroes_mapping", 
		joinColumns = {@JoinColumn(name = "HERO_ID", nullable = false, updatable = false)},
			inverseJoinColumns = { @JoinColumn(name = "HERO_BOOK_ID", nullable = false, updatable = false)})
	private Set<HeroBook> heroBooks = new HashSet<HeroBook>();
	

	public Hero() {
		super();
	}
	

	public Hero(String heroName, Integer heroAge) {
		super();
		this.heroName = heroName;
		this.heroAge = heroAge;
	}


	public Long getHeroId() {
		return heroId;
	}


	public void setHeroId(Long heroId) {
		this.heroId = heroId;
	}


	public String getHeroName() {
		return heroName;
	}


	public void setHeroName(String heroName) {
		this.heroName = heroName;
	}


	public Integer getHeroAge() {
		return heroAge;
	}


	public void setHeroAge(Integer heroAge) {
		this.heroAge = heroAge;
	}


	public Set<HeroBook> getHeroBooks() {
		return heroBooks;
	}


	public void setHeroBooks(Set<HeroBook> heroBooks) {
		this.heroBooks = heroBooks;
	}

}

File : HeroBook.java

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package com.devnp.hibernate.association.mtm.model;

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

import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

@Entity
@Table(name = "HERO_BOOK")
public class HeroBook {
	
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Basic(optional = false)
	@Column(name = "HERO_BOOK_ID")
	private Long heroBookId ;
	
	@Column(name = "HERO_BOOK_NAME")
	private String heroBookName ;
	
	@Column(name = "HERO_BOOK_PRICE")
	private Float heroBookPrice ;
	
	@ManyToMany(fetch = FetchType.LAZY, mappedBy="heroBooks")
	private Set<Hero> heros = new HashSet<Hero>();
	
	public HeroBook() {
		super();
	}
	
	public HeroBook(String heroBookName, Float heroBookPrice) {
		super();
		this.heroBookName = heroBookName;
		this.heroBookPrice = heroBookPrice;
	}

	public Long getHeroBookId() {
		return heroBookId;
	}

	public void setHeroBookId(Long heroBookId) {
		this.heroBookId = heroBookId;
	}

	public String getHeroBookName() {
		return heroBookName;
	}

	public void setHeroBookName(String heroBookName) {
		this.heroBookName = heroBookName;
	}

	public Float getHeroBookPrice() {
		return heroBookPrice;
	}

	public void setHeroBookPrice(Float heroBookPrice) {
		this.heroBookPrice = heroBookPrice;
	}

	public Set<Hero> getHeros() {
		return heros;
	}

	public void setHeros(Set<Hero> heros) {
		this.heros = heros;
	}

}

Hibernate SessionFactory

本例以属性配置的加载，更多获取SessionFactory的方式:Hibernate5 SessionFactory 的获取

添加Hero.java和HeroBook.java
File : HibernateProUtil.java

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package com.devnp.hibernate.util;

import java.util.Properties;

import org.hibernate.SessionFactory;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.model.naming.ImplicitNamingStrategyJpaCompliantImpl;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

import com.devnp.hibernate.association.mtm.model.Hero;
import com.devnp.hibernate.association.mto.model.Company;
import com.devnp.hibernate.association.mto.model.Employee;
import com.devnp.hibernate.association.otm.model.Book;
import com.devnp.hibernate.association.otm.model.Person;
import com.devnp.hibernate.association.oto.model.Student;
import com.devnp.hibernate.association.oto.model.Transcripts;

public class HibernateProUtil {

	private static SessionFactory sessionFactory = buildSessionFactory();

	private static SessionFactory buildSessionFactory() {
		Properties properties = new Properties();
	    properties.put("hibernate.dialect","org.hibernate.dialect.MySQL5InnoDBDialect"); //数据库方言
	    properties.put("hibernate.show_sql", "true");	//是否打印SQL
	    properties.put("hibernate.hbm2ddl.auto","update"); //执行跟新，及如果表不存在则会自动创建表
	    
	    properties.put("hibernate.format_sql", "true"); //格式化
	    
	    properties.put("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
	    properties.put("hibernate.connection.password", "!qaz2wsx");
	    properties.put("hibernate.connection.url", "jdbc:mysql://localhost:3306/test");
	    properties.put("hibernate.connection.username", "root");

	    /*StandardServiceRegistryBuilder standardServiceRegistryBuilder = new StandardServiceRegistryBuilder();
	    standardServiceRegistryBuilder.applySettings(properties);

	    MetadataSources metadataSources = new MetadataSources(standardServiceRegistryBuilder.build());
	    metadataSources.addAnnotatedClass(Student.class);*/
	    
	    StandardServiceRegistry serviceRegistry= new StandardServiceRegistryBuilder().applySettings(properties).build();
	    
	    MetadataSources metadataSources = new MetadataSources(serviceRegistry);
	    //add for one to one
	    metadataSources.addAnnotatedClass(Student.class).addAnnotatedClass(Transcripts.class);
	    
	    //add for one to many
	    metadataSources.addAnnotatedClass(Person.class).addAnnotatedClass(Book.class);
	    
	    //add for many to one
	    metadataSources.addAnnotatedClass(Employee.class).addAnnotatedClass(Company.class);
	    
	    //add for many to many
	    metadataSources.addAnnotatedClass(Hero.class).addAnnotatedClass(com.devnp.hibernate.association.mtm.model.HeroBook.class);
	    
	    Metadata metadata = metadataSources.getMetadataBuilder().applyImplicitNamingStrategy(
	    		ImplicitNamingStrategyJpaCompliantImpl.INSTANCE).build();
	    
	    sessionFactory = metadata.getSessionFactoryBuilder().build();  
	    
	    return sessionFactory;
	}

	public static SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	public static void shutdown() {
		// Close caches and connection pools
		getSessionFactory().close();
	}
}

测试

添加对象:
File : ManyToManyOperation.java

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package com.devnp.hibernate.association.operation;

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

import org.hibernate.Session;
import org.hibernate.SessionFactory;

import com.devnp.hibernate.association.mtm.model.Hero;
import com.devnp.hibernate.association.mtm.model.HeroBook;
import com.devnp.hibernate.util.HibernateProUtil;

public class ManyToManyOperation {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		save();
	}
	
	/**
	 * "Guo Jin" and "Huang Rou" belong "Eagle Shooting Heroes" book
	 * 
	 * "Yang Guo"  belong "Eagle Shooting Heroes" and "Shooting Knight" book
	 * 
	 */
	public static void save(){
		SessionFactory sessionFactory = HibernateProUtil.getSessionFactory();

		Session session = sessionFactory.openSession();

		session.getTransaction().begin();
		
		Hero hero1 = new Hero("Guo Jin", 33);
		Hero hero2 = new Hero("Huang Rou", 25);
		Hero hero3 = new Hero("Yang Guo", 22);
		
		HeroBook book1 = new HeroBook("Eagle Shooting Heroes", 22.3F);
		HeroBook book2 = new HeroBook("Shooting Knight", 23.5F);
		
		Set<HeroBook> heroBooks = new HashSet<HeroBook>();
		heroBooks.add(book1);
		
		hero1.setHeroBooks(heroBooks);
		hero2.setHeroBooks(heroBooks);
		
		hero3.getHeroBooks().add(book1);
		hero3.getHeroBooks().add(book2);
		
		session.save(hero1);
		session.save(hero2);
		session.save(hero3);
		
		session.getTransaction().commit();
		
		HibernateProUtil.shutdown();
	}
	
}

运行结果:

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Hibernate: 
    
    create table HERO (
       HERO_ID bigint not null auto_increment,
        HERO_AGE integer,
        HERO_NAME varchar(255),
        primary key (HERO_ID)
    ) engine=InnoDB
Hibernate: 
    
    create table HERO_BOOK (
       HERO_BOOK_ID bigint not null auto_increment,
        HERO_BOOK_NAME varchar(255),
        HERO_BOOK_PRICE float,
        primary key (HERO_BOOK_ID)
    ) engine=InnoDB
Hibernate: 
    
    create table heroes_mapping (
       HERO_ID bigint not null,
        HERO_BOOK_ID bigint not null,
        primary key (HERO_ID, HERO_BOOK_ID)
    ) engine=InnoDB
Hibernate: 
    
    alter table heroes_mapping 
       add constraint FKrkhpo49wk4l3waye5i32x884m 
       foreign key (HERO_BOOK_ID) 
       references HERO_BOOK (HERO_BOOK_ID)
Hibernate: 
    
    alter table heroes_mapping 
       add constraint FKbf749uoxlaf3ys4suui71jx4k 
       foreign key (HERO_ID) 
       references HERO (HERO_ID)
Hibernate: 
    insert 
    into
        HERO
        (HERO_AGE, HERO_NAME) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        HERO_BOOK
        (HERO_BOOK_NAME, HERO_BOOK_PRICE) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        HERO
        (HERO_AGE, HERO_NAME) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        HERO
        (HERO_AGE, HERO_NAME) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        HERO_BOOK
        (HERO_BOOK_NAME, HERO_BOOK_PRICE) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        heroes_mapping
        (HERO_ID, HERO_BOOK_ID) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        heroes_mapping
        (HERO_ID, HERO_BOOK_ID) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        heroes_mapping
        (HERO_ID, HERO_BOOK_ID) 
    values
        (?, ?)
Hibernate: 
    insert 
    into
        heroes_mapping
        (HERO_ID, HERO_BOOK_ID) 
    values
        (?, ?)

代码下载

java-hibernate-association-demo.zip