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Session SessionFactory 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sessionFactory sessionFactory.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:
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