Hibernate，JPA注解@ManyToMany_JoinTable

可以通过@ManyToMany注解可定义的多对多关联。同时，也需要通过注解@JoinTable描述关联表和关联条件。如果是双向关联，其中一段必须定义为owner，另一端必须定义为inverse(在对关联表进行更新操作时这一端将被忽略)。被关联端不必也不能描述物理映射: 只需要一个简单的mappedBy参数，该参数包含了主体端的属性名,这样就绑定双方的关系。

用例代码如下：

• 数据库DDL语句

1，CAT表

create table CAT
(
  id          VARCHAR2(32 CHAR) not null,
  create_time TIMESTAMP(6) default sysdate,
  update_time TIMESTAMP(6),
  cat_name    VARCHAR2(255 CHAR),
  first_name  VARCHAR2(255 CHAR),
  last_name   VARCHAR2(255 CHAR),
  version     NUMBER(10) not null
)

2，HOBBY表

create table HOBBY
(
  id          VARCHAR2(32 CHAR) not null,
  create_time TIMESTAMP(6),
  update_time TIMESTAMP(6),
  name        VARCHAR2(255 CHAR),
  cat_id      VARCHAR2(32 CHAR)
)

• hibernate.cfg.xml

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE hibernate-configuration
 PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- 数据库驱动配置 -->
        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
        <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property>
        <property name="connection.username">wxuatuser</property>
        <property name="connection.password">xlh</property>
        <property name="show_sql">true</property>
        <!-- 自动执行DDL属性是update，不是true -->
        <property name="hbm2ddl.auto">update</property>
        <!-- hibernate实体类 -->
        
        <mapping class="b12_ManyToMany_JoinTable.Cat"/>
        <mapping class="b12_ManyToMany_JoinTable.Hobby"/>
        
    </session-factory>
</hibernate-configuration>

• java类

实体类 - 基类 

package model;
import java.io.Serializable;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;
import org.hibernate.annotations.GenericGenerator;
/**
 * 实体类 - 基类
 */
@MappedSuperclass
public class BaseEntity implements Serializable {

    private static final long serialVersionUID = -6718838800112233445L;

    private String id;// ID
    private Date create_time;// 创建日期
    private Date update_time;// 修改日期
    @Id
    @Column(length = 32, nullable = true)
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid")
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    @Column(updatable = false)
    public Date getCreate_time() {
        return create_time;
    }
    public void setCreate_time(Date create_time) {
        this.create_time = create_time;
    }
    public Date getUpdate_time() {
        return update_time;
    }
    public void setUpdate_time(Date update_time) {
        this.update_time = update_time;
    }
    @Override
    public int hashCode() {
        return id == null ? System.identityHashCode(this) : id.hashCode();
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass().getPackage() != obj.getClass().getPackage()) {
            return false;
        }
        final BaseEntity other = (BaseEntity) obj;
        if (id == null) {
            if (other.getId() != null) {
                return false;
            }
        } else if (!id.equals(other.getId())) {
            return false;
        }
        return true;
    }
}

实体类

 Cat.java

package b12_ManyToMany_JoinTable;
import java.util.Set;
import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Version;
import model.BaseEntity;
import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;

@Entity
@DynamicInsert
@DynamicUpdate
public class Cat extends BaseEntity{
    /**
     * 实体类
     */
    private static final long serialVersionUID = -2776330321385582872L;
    
    private String cat_name;
    private Name name;
    private int version;
    
    private Set<Hobby> hobby;
    
    @ManyToMany(fetch = FetchType.EAGER)
    @Cascade({org.hibernate.annotations.CascadeType.SAVE_UPDATE})
    @JoinTable(name = "CAT_HOBBY", 
        joinColumns = { @JoinColumn(name = "CAT_ID") },
        inverseJoinColumns = { @JoinColumn(name = "HOBBY_ID") })
    public Set<Hobby> getHobby() {
        return hobby;
    }

    public void setHobby(Set<Hobby> hobby) {
        this.hobby = hobby;
    }    
    @Version
    public int getVersion() {
        return version;
    }

    public void setVersion(int version) {
        this.version = version;
    }

    public String getCat_name() {
        return cat_name;
    }

    public void setCat_name(String cat_name) {
        this.cat_name = cat_name;
    }

    @Embedded
    @AttributeOverrides({
            @AttributeOverride(name = "first_name", column = @Column(name = "first_name")),
            @AttributeOverride(name = "last_name", column = @Column(name = "last_name")) })
    public Name getName() {
        return name;
    }

    public void setName(Name name) {
        this.name = name;
    }    
}

Hobby.java

package b12_ManyToMany_JoinTable;
import java.util.Set;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.ManyToMany;
import model.BaseEntity;

@Entity
public class Hobby extends BaseEntity {
    /**
     * 实体类
     */
    private static final long serialVersionUID = 4921844599282935594L;
    
    private String name;
    private Set<Cat> cat;
    
    @ManyToMany(mappedBy = "hobby",fetch=FetchType.LAZY)
    public Set<Cat> getCat() {
        return cat;
    }
    public void setCat(Set<Cat> cat) {
        this.cat = cat;
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

组件类

package b12_ManyToMany_JoinTable;
import java.io.Serializable;
import javax.persistence.Embeddable;

@Embeddable
public class Name implements Serializable {
    /**
     * 嵌入式组建
     */
    private static final long serialVersionUID = -2776330321385582872L;
    
    private String first_name;
    private String last_name;
    public String getFirst_name() {
        return first_name;
    }
    public void setFirst_name(String first_name) {
        this.first_name = first_name;
    }
    public String getLast_name() {
        return last_name;
    }
    public void setLast_name(String last_name) {
        this.last_name = last_name;
    }    
}

Dao

package daoUtil;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

public class HibernateUtil {

    private static final SessionFactory sessionFactory;

    static {
        try {
            Configuration cfg = new Configuration().configure();
            ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
                    .applySettings(cfg.getProperties()).buildServiceRegistry();
            sessionFactory = cfg.buildSessionFactory(serviceRegistry);
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static Session getSession() throws HibernateException {
        return sessionFactory.openSession();
    }

    public static Object save(Object obj){
        Session session = HibernateUtil.getSession();
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            session.save(obj);
            tx.commit();
        } catch (RuntimeException e) {
            if (tx != null) {
                tx.rollback();
            }
            throw e;
        } finally {
            session.close();
        }
        return obj;
    }
    
    public static void delete(Class<?> clazz,String id){
        Session session = HibernateUtil.getSession();
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            Object obj = session.get(clazz,id);
            session.delete(obj);
            tx.commit();
        } catch (RuntimeException e) {
            if (tx != null) {
                tx.rollback();
            }
            throw e;
        } finally {
            session.close();
        }
    }
}

main

package b12_ManyToMany_JoinTable;
import java.util.HashSet;
import java.util.Set;
import daoUtil.HibernateUtil;

public class Test_ManyToMany_JoinTable {

    private Cat save(){
        Cat cat1 = new Cat();
        Cat cat2 = new Cat();
        cat1.setCat_name("b12_ManyToMany_JoinTable1");
        cat2.setCat_name("b12_ManyToMany_JoinTable2");

        Set<Hobby> hobbies = new HashSet<Hobby>();
        Hobby hobby1 = new Hobby();
        hobby1.setName("乒乓球");
        hobbies.add(hobby1);
        
        Hobby hobby2 = new Hobby();
        hobby2.setName("冰球");
        hobbies.add(hobby2);
        
        cat1.setHobby(hobbies);
        cat2.setHobby(hobbies);
        
        HibernateUtil.save(cat1);
        HibernateUtil.save(cat2);
        System.out.println(cat1.getId());
        System.out.println(cat2.getId());
        return cat1;
    }
    
    public static void main(String[] args) {
        // 通过cat加载hobby
        Cat cat = new Test_ManyToMany_JoinTable().save();
        
//        Cat cat1 = (Cat)HibernateUtil.getSession().get(Cat.class, "8a6cc5a34c77d08f014c77d0a0490003");
//        System.out.println(cat1.getId());
//        
//        Set<Hobby> hobbies = cat1.getHobby();
//        for (Hobby hobby : hobbies) {
//            System.out.println(hobby.getName());
//        }
//        
//        // delete
//        HibernateUtil.delete(Cat.class, "8a6cc5a34c77d08f014c77d0a0490003");
        
        // 通过hobby加载cat
//        Hobby hobby = (Hobby)HibernateUtil.getSession().get(Hobby.class, "8a6cc5a34c77d08f014c77d09fbb0001");
//        System.out.println(hobby.getId());
//        
//        Set<Cat> cats = hobby.getCat();
//        for (Cat cat : cats) {
//            System.out.println(cat.getCat_name());
//        }
    }
}

环境：JDK1.6，MAVEN，tomcat，eclipse

源码地址：http://files.cnblogs.com/files/xiluhua/hibernate%40ManyToMany_JoinTable.rar