• 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

     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 null
10 )

    2，HOBBY表

    1 create table HOBBY
2 (
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 <?xml version="1.0" encoding="utf-8" ?>
 2 <!DOCTYPE hibernate-configuration
 3  PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
 4  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
 5 <hibernate-configuration>
 6     <session-factory>
 7         <!-- 数据库驱动配置 -->
 8         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
 9         <property name="connection.driver_class">oracle.jdbc.OracleDriver</property>
10         <property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property>
11         <property name="connection.username">wxuatuser</property>
12         <property name="connection.password">xlh</property>
13         <property name="show_sql">true</property>
14         <!-- 自动执行DDL属性是update，不是true -->
15         <property name="hbm2ddl.auto">update</property>
16         <!-- hibernate实体类 -->
17         
18         <mapping class="b12_ManyToMany_JoinTable.Cat"/>
19         <mapping class="b12_ManyToMany_JoinTable.Hobby"/>
20         
21     </session-factory>
22 </hibernate-configuration>
    • 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 @MappedSuperclass
13 public class BaseEntity implements Serializable {
14 
15     private static final long serialVersionUID = -6718838800112233445L;
16 
17     private String id;// ID
18     private Date create_time;// 创建日期
19     private Date update_time;// 修改日期
20     @Id
21     @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     @Override
44     public int hashCode() {
45         return id == null ? System.identityHashCode(this) : id.hashCode();
46     }
47     @Override
48     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 @Entity
19 @DynamicInsert
20 @DynamicUpdate
21 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> 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<Hobby> getHobby() {
39         return hobby;
40     }
41 
42     public void setHobby(Set<Hobby> hobby) {
43         this.hobby = hobby;
44     }    
45     @Version
46     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     @Embedded
63     @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> cat;
17     
18     @ManyToMany(mappedBy = "hobby",fetch=FetchType.LAZY)
19     public Set<Cat> getCat() {
20         return cat;
21     }
22     public void setCat(Set<Cat> 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<Hobby> hobbies = new HashSet<Hobby>();
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hobby
35         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<Hobby> hobbies = cat1.getHobby();
41 //        for (Hobby hobby : hobbies) {
42 //            System.out.println(hobby.getName());
43 //        }
44 //        
45 //        // delete
46 //        HibernateUtil.delete(Cat.class, "8a6cc5a34c77d08f014c77d0a0490003");
47         
48         // 通过hobby加载cat
49 //        Hobby hobby = (Hobby)HibernateUtil.getSession().get(Hobby.class, "8a6cc5a34c77d08f014c77d09fbb0001");
50 //        System.out.println(hobby.getId());
51 //        
52 //        Set<Cat> 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
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  • 原文地址：https://www.cnblogs.com/xiluhua/p/4386045.html
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