hibernate hibernate.cfg.xml component 组件

Posted 2020-08-01 信天翁游记

1.为什么使用component组件？

当一个表的列数目比较多时，可以根据属性分类，将一个java对象拆分为几个对象。

数据库还是一张表，不过有多个对象与之对应。

2.实例

2.1 Java 对象：

 1 public class Person {
 2 
 3     private int id;
 4     private Name name;
 5     private Parents parents;
 6 
 7     public Parents getParents() {
 8         return parents;
 9     }
10 
11     public void setParents(Parents parents) {
12         this.parents = parents;
13     }
14 
15     public int getId() {
16         return id;
17     }
18 
19     public void setId(int id) {
20         this.id = id;
21     }
22 
23     public Name getName() {
24         return name;
25     }
26 
27     public void setName(Name name) {
28         this.name = name;
29     }
30 }

 1 public class Parents {
 2     private Name father;
 3     private Name mother;
 4 
 5     public Name getFather() {
 6         return father;
 7     }
 8 
 9     public void setFather(Name father) {
10         this.father = father;
11     }
12 
13     public Name getMother() {
14         return mother;
15     }
16 
17     public void setMother(Name mother) {
18         this.mother = mother;
19     }
20 }

 1 public class Name {
 2     private String bigName;
 3     private String nickName;
 4     private int nameVersion;
 5 
 6     public String getBigName() {
 7         return bigName;
 8     }
 9 
10     public void setBigName(String bigName) {
11         this.bigName = bigName;
12     }
13 
14     public int getNameVersion() {
15         return nameVersion;
16     }
17 
18     public void setNameVersion(int nameVersion) {
19         this.nameVersion = nameVersion;
20     }
21 
22     public String getNickName() {
23         return nickName;
24     }
25 
26     public void setNickName(String nickName) {
27         this.nickName = nickName;
28     }
29 }

2.2 Hibernate 配置文件 hibernate.cfg.xml

 1 <?xml version="1.0" encoding="utf-8" ?>
 2 <!DOCTYPE hibernate-configuration PUBLIC
 3         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"
 5         >
 6 <hibernate-configuration>
 7     <session-factory>
 8         <!-- Platform settings -->
 9         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
10         <property name="connection.url">jdbc:mysql://localhost:3306/test</property>
11         <property name="connection.username">root</property>
12         <property name="connection.password">123456</property>
13         <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
14         <!-- Miscellaneous Settings -->
15         <property name="show_sql">true</property>
16         <!--mapping files-->
17         <mapping resource="test/com/hibernate/config/hbm/person.hbm.xml"/>
18     </session-factory>
19 
20 </hibernate-configuration>

映射文件person.hbm.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 5 <hibernate-mapping>
 6     <class name="test.com.hibernate.component.Person" table="person" lazy="false">
 7         <id name="id" column="id" type="java.lang.Integer">
 8             <generator class="native"/>
 9         </id>
10         <component name="name" class="test.com.hibernate.component.Name" >
11             <property name="bigName" column="bigName" type="string"/>
12             <property name="nickName" column="nickName" type="string"/>
13             <property name="nameVersion" column="nameVersion" type="integer"/>
14         </component>
15         <component name="parents" class="test.com.hibernate.component.Parents">
16             <component name="father" class="test.com.hibernate.component.Name">
17                 <property name="bigName" column="f_bigName" type="string"/>
18                 <property name="nickName" column="f_nickName" type="string"/>
19                 <property name="nameVersion" column="f_nameVersion" type="integer"/>
20             </component>
21             <component name="mother" class="test.com.hibernate.component.Name">
22                 <property name="bigName" column="m_bigName" type="string"/>
23                 <property name="nickName" column="m_nickName" type="string"/>
24                 <property name="nameVersion" column="m_nameVersion" type="integer"/>
25             </component>
26         </component>
27     </class>
28 </hibernate-mapping>

2.3 Hibernate 操作代码：

HibernateUtil.java

 1 public class HibernateUtil {
 2     static SessionFactory sessionFactory = null;
 3     static{
 4         StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
 5                 .configure("test/com/hibernate/config/hibernate.cfg.xml").build();
 6         MetadataSources sources = new MetadataSources();
 7         Metadata metadata = sources.buildMetadata(registry);
 8         sessionFactory = metadata.buildSessionFactory();
 9     }
10     public static Session openSession(){
11         if(sessionFactory==null){
12             throw new HibernateException("session factory is null!");
13         }
14         return sessionFactory.openSession();
15     }
16     public static void destroy() {
17         if(sessionFactory!=null){
18             sessionFactory.close();
19         }
20     }
21 }

Test.java

 1 public class Test {
 2 
 3     public static void main(String[] args) {
 4 
 5         Name name = new Name();
 6         name.setBigName("Daughter");
 7         name.setNickName("girl");
 8         name.setNameVersion(1);
 9         Person person = new Person();
10         person.setName(name);
11 
12         Name father = new Name();
13         father.setBigName("Father");
14         father.setNickName("man");
15         father.setNameVersion(1);
16         Name mother = new Name();
17         mother.setBigName("Mother");
18         mother.setNickName("woman");
19         mother.setNameVersion(1);
20 
21         Parents parents = new Parents();
22         parents.setFather(father);
23         parents.setMother(mother);
24 
25         person.setParents(parents);
26 
27         PersonDao.save(person);
28     }
29 }

上述例子使用Hibernate版本为5.2Final，配置文件也可以用以前的Configuration配置。

2.4 运行结果

自动创建一个person表，并插入一条数据