Hibernate Component映射的一个简单例子
建立一个相关的数据库表：
create table c_user(id int(11) not null auto_increment,age int(11) default null,firstname varchar(50) default null,lastname varchar(50) default null,address varchar(200) default null,zipcode varchar(10) default null,tel varchar(20) default null,primary key(id))engine=innodb default charset=gbk;
注解：该表是一个用户信息表，可以将用户信息归纳为两个部分：一个部分是name(姓名)，包含firstname(姓)和lastname(名)；另一部分是contact(联系方式)，包括了address(地址)、zipcode(邮编)和tel(电话)等信息。在创建实体类时，可以将name和contact分别封装到2个独立的类中，这样就提高了系统的复用性和灵活性。也就是说，需要使用Component映射，将其他的实体类映射在一起。
建立一个Name.java类：
package collect.component;import java.io.Serializable;public class Name implements Serializable { private String firstname; private String lastname; public String getFirstname() { return firstname; } public void setFirstname(String firstname) { this.firstname = firstname; } public String getLastname() { return lastname; } public void setLastname(String lastname) { this.lastname = lastname; } }建立联系方式相关的类Contact.java：
package collect.component;import java.io.Serializable;public class Contact implements Serializable{private String address;private String zipcodes;private String tel;public Contact() {}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public String getZipcodes() {return zipcodes;}public void setZipcodes(String zipcodes) {this.zipcodes = zipcodes;}public String getTel() {return tel;}public void setTel(String tel) {this.tel = tel;}}最后建立数据库表对应的实体类Cuser.java：
package collect.component;public class Cuser {private Integer id;private Integer age;private Name name;private Contact contact;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public Name getName() {return name;}public void setName(Name name) {this.name = name;}public Contact getContact() {return contact;}public void setContact(Contact contact) {this.contact = contact;}}建立映射文件Cuser.hbm.xml：
<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping> <class name="collect.component.Cuser" table="c_user" catalog="ssh"> <id name="id" type="integer"> <column name="id" /> <generator class="native" /> </id> <property name="age" type="integer"> <column name="age" /> </property> <component name="name" class="collect.component.Name"> <property name="firstname" type="string"> <column name="firstname" length="50" /> </property> <property name="lastname" type="string"> <column name="lastname" length="50" /> </property> </component> <component name="contact" class="collect.component.Contact"> <property name="address" type="string"> <column name="address" length="200" /> </property> <property name="zipcodes" type="string"> <column name="zipcode" length="10" /> </property> <property name="tel" type="string"> <column name="tel" length="20" /> </property> </component> </class></hibernate-mapping>
注解：映射文件使用component元素将Name类、Contact类同数据库表c_user联系起来。
将该映射文件加入到Hibernate的配置文件中，建立一个测试类Test.java：
package collect.component;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.Transaction;import org.hibernate.cfg.Configuration;public class Test {public static void main(String[] args) {// Configuration管理Hibernate配置Configuration config = new Configuration().configure();// 根据Configuration建立 SessionFactory// SessionFactory用来建立SessionSessionFactory sessionFactory = config.buildSessionFactory();// 创建实例Name name=new Name();name.setFirstname("闫");name.setLastname("术卓");Contact contact = new Contact(); contact.setAddress("北京"); contact.setTel("42689334"); contact.setZipcodes("100085"); Cuser user= new Cuser();user.setAge(33);user.setName(name);user.setContact(contact);// 定义主键变量Integer pid;// 添加数据Session session = sessionFactory.openSession();Transaction tx = null;try {tx = session.beginTransaction();// 创建主键变量pid = (Integer) session.save(user);tx.commit();} catch (RuntimeException e) {if (tx != null)tx.rollback();throw e;} finally {session.close();}// 关闭sessionFactorysessionFactory.close();}}
运行结果：
控制台：
20:47:57,366 DEBUG SQL:346 - insert intossh.c_user (age, firstname, lastname, address, zipcode, tel) values (?, ?, ?,?, ?, ?)
数据库：
