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
1 create table CAT 2 ( 3 id VARCHAR2(32 CHAR) not null, 4 create_time TIMESTAMP(6) default sysdate, 5 update_time TIMESTAMP(6), 6 cat_name VARCHAR2(255 CHAR), 7 first_name VARCHAR2(255 CHAR), 8 last_name VARCHAR2(255 CHAR), 9 version NUMBER(10) not null10 )
2，HOBBY表
1 create table HOBBY2 (3 id VARCHAR2(32 CHAR) not null,4 create_time TIMESTAMP(6),5 update_time TIMESTAMP(6),6 name VARCHAR2(255 CHAR),7 cat_id VARCHAR2(32 CHAR)8 )
- hibernate.cfg.xml
1 2 56 7 8 22org.hibernate.dialect.Oracle10gDialect 9oracle.jdbc.OracleDriver 10jdbc:oracle:thin:@127.0.0.1:1521:orcl 11wxuatuser 12xlh 13true 14 15update 16 17 1819 20 21
- java类
实体类 - 基类
1 package model; 2 import java.io.Serializable; 3 import java.util.Date; 4 import javax.persistence.Column; 5 import javax.persistence.GeneratedValue; 6 import javax.persistence.Id; 7 import javax.persistence.MappedSuperclass; 8 import org.hibernate.annotations.GenericGenerator; 9 /**10 * 实体类 - 基类11 */12 @MappedSuperclass13 public class BaseEntity implements Serializable {14 15 private static final long serialVersionUID = -6718838800112233445L;16 17 private String id;// ID18 private Date create_time;// 创建日期19 private Date update_time;// 修改日期20 @Id21 @Column(length = 32, nullable = true)22 @GeneratedValue(generator = "uuid")23 @GenericGenerator(name = "uuid", strategy = "uuid")24 public String getId() {25 return id;26 }27 public void setId(String id) {28 this.id = id;29 }30 @Column(updatable = false)31 public Date getCreate_time() {32 return create_time;33 }34 public void setCreate_time(Date create_time) {35 this.create_time = create_time;36 }37 public Date getUpdate_time() {38 return update_time;39 }40 public void setUpdate_time(Date update_time) {41 this.update_time = update_time;42 }43 @Override44 public int hashCode() {45 return id == null ? System.identityHashCode(this) : id.hashCode();46 }47 @Override48 public boolean equals(Object obj) {49 if (this == obj) {50 return true;51 }52 if (obj == null) {53 return false;54 }55 if (getClass().getPackage() != obj.getClass().getPackage()) {56 return false;57 }58 final BaseEntity other = (BaseEntity) obj;59 if (id == null) {60 if (other.getId() != null) {61 return false;62 }63 } else if (!id.equals(other.getId())) {64 return false;65 }66 return true;67 }68 } 实体类
Cat.java
1 package b12_ManyToMany_JoinTable; 2 import java.util.Set; 3 import javax.persistence.AttributeOverride; 4 import javax.persistence.AttributeOverrides; 5 import javax.persistence.Column; 6 import javax.persistence.Embedded; 7 import javax.persistence.Entity; 8 import javax.persistence.FetchType; 9 import javax.persistence.JoinColumn;10 import javax.persistence.JoinTable;11 import javax.persistence.ManyToMany;12 import javax.persistence.Version;13 import model.BaseEntity;14 import org.hibernate.annotations.Cascade;15 import org.hibernate.annotations.DynamicInsert;16 import org.hibernate.annotations.DynamicUpdate;17 18 @Entity19 @DynamicInsert20 @DynamicUpdate21 public class Cat extends BaseEntity{22 /**23 * 实体类24 */25 private static final long serialVersionUID = -2776330321385582872L;26 27 private String cat_name;28 private Name name;29 private int version;30 31 private Set hobby;32 33 @ManyToMany(fetch = FetchType.EAGER)34 @Cascade({org.hibernate.annotations.CascadeType.SAVE_UPDATE})35 @JoinTable(name = "CAT_HOBBY", 36 joinColumns = { @JoinColumn(name = "CAT_ID") },37 inverseJoinColumns = { @JoinColumn(name = "HOBBY_ID") })38 public Set getHobby() {39 return hobby;40 }41 42 public void setHobby(Set hobby) {43 this.hobby = hobby;44 } 45 @Version46 public int getVersion() {47 return version;48 }49 50 public void setVersion(int version) {51 this.version = version;52 }53 54 public String getCat_name() {55 return cat_name;56 }57 58 public void setCat_name(String cat_name) {59 this.cat_name = cat_name;60 }61 62 @Embedded63 @AttributeOverrides({64 @AttributeOverride(name = "first_name", column = @Column(name = "first_name")),65 @AttributeOverride(name = "last_name", column = @Column(name = "last_name")) })66 public Name getName() {67 return name;68 }69 70 public void setName(Name name) {71 this.name = name;72 } 73 } Hobby.java
1 package b12_ManyToMany_JoinTable; 2 import java.util.Set; 3 import javax.persistence.Entity; 4 import javax.persistence.FetchType; 5 import javax.persistence.ManyToMany; 6 import model.BaseEntity; 7 8 @Entity 9 public class Hobby extends BaseEntity {10 /**11 * 实体类12 */13 private static final long serialVersionUID = 4921844599282935594L;14 15 private String name;16 private Set cat;17 18 @ManyToMany(mappedBy = "hobby",fetch=FetchType.LAZY)19 public Set getCat() {20 return cat;21 }22 public void setCat(Set cat) {23 this.cat = cat;24 }25 26 public String getName() {27 return name;28 }29 public void setName(String name) {30 this.name = name;31 }32 } 组件类
1 package b12_ManyToMany_JoinTable; 2 import java.io.Serializable; 3 import javax.persistence.Embeddable; 4 5 @Embeddable 6 public class Name implements Serializable { 7 /** 8 * 嵌入式组建 9 */10 private static final long serialVersionUID = -2776330321385582872L;11 12 private String first_name;13 private String last_name;14 public String getFirst_name() {15 return first_name;16 }17 public void setFirst_name(String first_name) {18 this.first_name = first_name;19 }20 public String getLast_name() {21 return last_name;22 }23 public void setLast_name(String last_name) {24 this.last_name = last_name;25 } 26 } Dao
1 package daoUtil; 2 import org.hibernate.HibernateException; 3 import org.hibernate.Session; 4 import org.hibernate.SessionFactory; 5 import org.hibernate.Transaction; 6 import org.hibernate.cfg.Configuration; 7 import org.hibernate.service.ServiceRegistry; 8 import org.hibernate.service.ServiceRegistryBuilder; 9 10 public class HibernateUtil {11 12 private static final SessionFactory sessionFactory;13 14 static {15 try {16 Configuration cfg = new Configuration().configure();17 ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()18 .applySettings(cfg.getProperties()).buildServiceRegistry();19 sessionFactory = cfg.buildSessionFactory(serviceRegistry);20 } catch (Throwable ex) {21 throw new ExceptionInInitializerError(ex);22 }23 }24 25 public static Session getSession() throws HibernateException {26 return sessionFactory.openSession();27 }28 29 public static Object save(Object obj){30 Session session = HibernateUtil.getSession();31 Transaction tx = null;32 try {33 tx = session.beginTransaction();34 session.save(obj);35 tx.commit();36 } catch (RuntimeException e) {37 if (tx != null) {38 tx.rollback();39 }40 throw e;41 } finally {42 session.close();43 }44 return obj;45 }46 47 public static void delete(Class clazz,String id){48 Session session = HibernateUtil.getSession();49 Transaction tx = null;50 try {51 tx = session.beginTransaction();52 Object obj = session.get(clazz,id);53 session.delete(obj);54 tx.commit();55 } catch (RuntimeException e) {56 if (tx != null) {57 tx.rollback();58 }59 throw e;60 } finally {61 session.close();62 }63 }64 } main
1 package b12_ManyToMany_JoinTable; 2 import java.util.HashSet; 3 import java.util.Set; 4 import daoUtil.HibernateUtil; 5 6 public class Test_ManyToMany_JoinTable { 7 8 private Cat save(){ 9 Cat cat1 = new Cat();10 Cat cat2 = new Cat();11 cat1.setCat_name("b12_ManyToMany_JoinTable1");12 cat2.setCat_name("b12_ManyToMany_JoinTable2");13 14 Set hobbies = new HashSet ();15 Hobby hobby1 = new Hobby();16 hobby1.setName("乒乓球");17 hobbies.add(hobby1);18 19 Hobby hobby2 = new Hobby();20 hobby2.setName("冰球");21 hobbies.add(hobby2);22 23 cat1.setHobby(hobbies);24 cat2.setHobby(hobbies);25 26 HibernateUtil.save(cat1);27 HibernateUtil.save(cat2);28 System.out.println(cat1.getId());29 System.out.println(cat2.getId());30 return cat1;31 }32 33 public static void main(String[] args) {34 // 通过cat加载hobby35 Cat cat = new Test_ManyToMany_JoinTable().save();36 37 // Cat cat1 = (Cat)HibernateUtil.getSession().get(Cat.class, "8a6cc5a34c77d08f014c77d0a0490003");38 // System.out.println(cat1.getId());39 // 40 // Set hobbies = cat1.getHobby();41 // for (Hobby hobby : hobbies) {42 // System.out.println(hobby.getName());43 // }44 // 45 // // delete46 // HibernateUtil.delete(Cat.class, "8a6cc5a34c77d08f014c77d0a0490003");47 48 // 通过hobby加载cat49 // Hobby hobby = (Hobby)HibernateUtil.getSession().get(Hobby.class, "8a6cc5a34c77d08f014c77d09fbb0001");50 // System.out.println(hobby.getId());51 // 52 // Set cats = hobby.getCat();53 // for (Cat cat : cats) {54 // System.out.println(cat.getCat_name());55 // }56 }57 }
环境：JDK1.6，MAVEN，tomcat，eclipse
源码地址：http://files.cnblogs.com/files/xiluhua/hibernate%40ManyToMany_JoinTable.rar