hibernate hibernate.cfg.xml component 组件

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：

 public class Person {     private int id;
     private Name name;
     private Parents parents;     public Parents getParents() {
         return parents;
     }     public void setParents(Parents parents) {
         this.parents = parents;
     }     public int getId() {
         return id;
     }     public void setId(int id) {
         this.id = id;
     }     public Name getName() {
         return name;
     }     public void setName(Name name) {
         this.name = name;
     }
 }

 public class Parents {
     private Name father;
     private Name mother;     public Name getFather() {
         return father;
     }     public void setFather(Name father) {
         this.father = father;
     }     public Name getMother() {
         return mother;
     }     public void setMother(Name mother) {
         this.mother = mother;
     }
 }

 public class Name {
     private String bigName;
     private String nickName;
     private int nameVersion;     public String getBigName() {
         return bigName;
     }     public void setBigName(String bigName) {
         this.bigName = bigName;
     }     public int getNameVersion() {
         return nameVersion;
     }     public void setNameVersion(int nameVersion) {
         this.nameVersion = nameVersion;
     }     public String getNickName() {
         return nickName;
     }     public void setNickName(String nickName) {
         this.nickName = nickName;
     }
 }

2.2 Hibernate 配置文件 hibernate.cfg.xml

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE hibernate-configuration PUBLIC
         "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
         "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"
         >
 <hibernate-configuration>
     <session-factory>
         <!-- Platform settings -->
         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
         <property name="connection.url">jdbc:mysql://localhost:3306/test</property>
         <property name="connection.username">root</property>
         <property name="connection.password">123456</property>
         <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
         <!-- Miscellaneous Settings -->
         <property name="show_sql">true</property>
         <!--mapping files-->
         <mapping resource="test/com/hibernate/config/hbm/person.hbm.xml"/>
     </session-factory> </hibernate-configuration>

映射文件person.hbm.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!DOCTYPE hibernate-mapping PUBLIC
         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
         "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
 <hibernate-mapping>
     <class name="test.com.hibernate.component.Person" table="person" lazy="false">
         <id name="id" column="id" type="java.lang.Integer">
             <generator class="native"/>
         </id>
         <component name="name" class="test.com.hibernate.component.Name" >
             <property name="bigName" column="bigName" type="string"/>
             <property name="nickName" column="nickName" type="string"/>
             <property name="nameVersion" column="nameVersion" type="integer"/>
         </component>
         <component name="parents" class="test.com.hibernate.component.Parents">
             <component name="father" class="test.com.hibernate.component.Name">
                 <property name="bigName" column="f_bigName" type="string"/>
                 <property name="nickName" column="f_nickName" type="string"/>
                 <property name="nameVersion" column="f_nameVersion" type="integer"/>
             </component>
             <component name="mother" class="test.com.hibernate.component.Name">
                 <property name="bigName" column="m_bigName" type="string"/>
                 <property name="nickName" column="m_nickName" type="string"/>
                 <property name="nameVersion" column="m_nameVersion" type="integer"/>
             </component>
         </component>
     </class>
 </hibernate-mapping>

2.3 Hibernate 操作代码：

HibernateUtil.java

 public class HibernateUtil {
     static SessionFactory sessionFactory = null;
     static{
         StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                 .configure("test/com/hibernate/config/hibernate.cfg.xml").build();
         MetadataSources sources = new MetadataSources();
         Metadata metadata = sources.buildMetadata(registry);
         sessionFactory = metadata.buildSessionFactory();
     }
     public static Session openSession(){
         if(sessionFactory==null){
             throw new HibernateException("session factory is null!");
         }
         return sessionFactory.openSession();
     }
     public static void destroy() {
         if(sessionFactory!=null){
             sessionFactory.close();
         }
     }
 }

Test.java

 public class Test {     public static void main(String[] args) {         Name name = new Name();
         name.setBigName("Daughter");
         name.setNickName("girl");
         name.setNameVersion(1);
         Person person = new Person();
         person.setName(name);         Name father = new Name();
         father.setBigName("Father");
         father.setNickName("man");
         father.setNameVersion(1);
         Name mother = new Name();
         mother.setBigName("Mother");
         mother.setNickName("woman");
         mother.setNameVersion(1);         Parents parents = new Parents();
         parents.setFather(father);
         parents.setMother(mother);         person.setParents(parents);         PersonDao.save(person);
     }
 }

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