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hibernate 建表一对一 就是一对多，多的一方外键唯一unique

2024-07-07 15:09:09   226人阅读

Person.java

 1 package cn.itcast.hiberate.sh.domain.onetoone;
 2 
 3 import java.io.Serializable;
 4 import java.util.Set;
 5 
 6 public class Person implements Serializable{
 7     private Long cid;
 8     private String cname;
 9     private String description;
10     
11     public Long getCid() {
12         return cid;
13     }
14 
15     public void setCid(Long cid) {
16         this.cid = cid;
17     }
18 
19     public String getCname() {
20         return cname;
21     }
22 
23     public void setCname(String cname) {
24         this.cname = cname;
25     }
26 
27     public String getDescription() {
28         return description;
29     }
30 
31     public void setDescription(String description) {
32         this.description = description;
33     }
34     
35     public Address getAddress() {
36         return address;
37     }
38 
39     public void setAddress(Address address) {
40         this.address = address;
41     }
42 
43     private Address address;
44 }

Person.hbm.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 4 <hibernate-mapping>
 5     <class name="cn.itcast.hiberate.sh.domain.Classes">
 6         <id name="cid" length="5" type="java.lang.Long">
 7             <generator class="increment"></generator>
 8         </id>
 9         <property name="cname" length="20" type="java.lang.String"></property>
10         
11         <property name="description" length="100" type="java.lang.String"></property>
12         <!-- 
13             set元素对应类中的set集合
14             通过set元素使classes表与student表建立关联
15                key是通过外键的形式让两张表建立关联
16                one-to-many是通过类的形式让两个类建立关联
17             
18             cascade 级联
19                save-update
20                    1、当 保存班级的时候，对学生进行怎么样的操作
21                         如果学生对象在数据库中没有对应的值，这个时候会执行save操作
22                         如果学生对象在数据库中有对应的值，这个时候会执行update操作
23                delete
24                all
25             inverse  维护关系
26                true      不维护关系     
27                false     维护关系
28                default   false
29          -->
30         <set name="students" cascade="save-update" inverse="true">
31             <!-- 
32                 key是用来描述外键
33              -->
34             <key>
35                 <column name="cid"></column>
36             </key>
37             <one-to-many class="cn.itcast.hiberate.sh.domain.Student"/>
38         </set>
39     </class>
40 </hibernate-mapping>

Address.java

 1 package cn.itcast.hiberate.sh.domain.onetoone;
 2 
 3 import java.io.Serializable;
 4 
 5 public class Address implements Serializable{
 6     private Long sid;
 7     private String sname;
 8     
 9     private Person person;
10     
11 
12     public Person getPerson() {
13         return person;
14     }
15     public void setPerson(Person person) {
16         this.person = person;
17     }
18     public Long getSid() {
19         return sid;
20     }
21     public void setSid(Long sid) {
22         this.sid = sid;
23     }
24     public String getSname() {
25         return sname;
26     }
27     public void setSname(String sname) {
28         this.sname = sname;
29     }
30     public String getDescription() {
31         return description;
32     }
33     public void setDescription(String description) {
34         this.description = description;
35     }
36     private String description;
37 }

Address.hbm.xml  外键唯一

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 4 <hibernate-mapping>
 5     <class name="cn.itcast.hiberate.sh.domain.Student">
 6         <id name="sid" length="5">
 7             <generator class="increment"></generator>
 8         </id>
 9         <property name="sname" length="20"></property>
10         <property name="description" length="100"></property>
11         <!-- 
12             多对一
13               column 外键
14          -->
15         <many-to-one name="classes" class="cn.itcast.hiberate.sh.domain.Classes" column="cid" cascade="save-update" unique="true"></many-to-one>
16     </class>
17 </hibernate-mapping>

 

 


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