注解-单向一对多演示

Posted 2020-10-10 友情天

首先定义2个实体类:Cate.java和Sub.java

单向一对多：一方有集合属性，包含多个多方，而多方没有一方的引用

 1 package com.yztc.app.entity;
 2 
 3 import javax.persistence.*;
 4 import java.util.Set;
 5 
 6 @Entity
 7 @Table(name = "TB_CATE")
 8 public class Cate {
 9     @Id
10     @GeneratedValue//用于定义主键生成策略
11     @Column(name = "CID",length = 10)
12     private Long cid;
13     @Column(name = "NAME",length = 64)
14     private String name;
15     @OneToMany(cascade = CascadeType.ALL)
16     @JoinColumn(name = "CID")
17     private Set<Sub> subs;
18 
19     public Set<Sub> getSubs() {
20         return subs;
21     }
22 
23     public void setSubs(Set<Sub> subs) {
24         this.subs = subs;
25     }
26 
27     public Long getCid() {
28         return cid;
29     }
30 
31     public void setCid(Long cid) {
32         this.cid = cid;
33     }
34 
35     public String getName() {
36         return name;
37     }
38 
39     public void setName(String name) {
40         this.name = name;
41     }
42 
43     public Cate() {
44     }
45 
46     public Cate(String name) {
47         this.name = name;
48     }
49 }

 1 package com.yztc.app.entity;
 2 
 3 import javax.persistence.*;
 4 
 5 @Entity
 6 @Table(name = "TB_SUB")
 7 public class Sub {
 8     @Id
 9     @GeneratedValue//用于定义主键生成策略
10     @Column(name = "SID",length = 10)
11     private Long sid;
12     @Column(name = "NAME",length = 64)
13     private String name;
14 
15 
16     public Sub() {
17     }
18 
19     public Long getSid() {
20 
21         return sid;
22     }
23 
24     public void setSid(Long sid) {
25         this.sid = sid;
26     }
27 
28     public String getName() {
29         return name;
30     }
31 
32     public void setName(String name) {
33         this.name = name;
34     }
35 
36     public Sub(String name) {
37         this.name = name;
38     }
39 }

二.单元测试:

 1 package com.yztc.test;
 2 
 3 
 4 import com.yztc.app.entity.Cate;
 5 import com.yztc.app.entity.Sub;
 6 import org.hibernate.Session;
 7 import org.hibernate.SessionFactory;
 8 import org.hibernate.Transaction;
 9 import org.hibernate.cfg.Configuration;
10 import org.junit.After;
11 import org.junit.Before;
12 import org.junit.Test;
13 
14 import java.util.HashSet;
15 import java.util.Set;
16 
17 public class TestOneToMany {
18 
19     private SessionFactory sf;
20     private Session session;
21 
22     @Before
23     public void init(){
24         sf = new Configuration().configure().buildSessionFactory();
25         session = sf.openSession();
26 
27     }
28     //测试一对多单向
29     @Test
30     public void testSave(){
31         Transaction transaction = session.beginTransaction();
32         Cate cate = new Cate("手机");
33         Set<Sub> sets = new HashSet<>();
34         for (int i = 0; i < 10; i++) {
35             Sub sub = new Sub("魅族" + i);
36             sets.add(sub);
37             session.save(sub);
38         }
39        cate.setSubs(sets);
40         session.save(cate);
41         transaction.commit();
42 
43 
44     }
45     @After
46     public void destory(){
47         session.close();
48     }
49 }