需求: 在T_STUDENTS表中 要将ID和NAME联合作为主键:
1.将id和name属性定义到一个主键类中:StudentPK 并重写hashCode()和equals()方法同时要继承Serializable接口
package com.zchen.hibernate.sxt.domain; import java.io.Serializable; public class StudentPK implements Serializable{ /** * */ private static final long serialVersionUID = -7880746333829652369L; private int id; private String name; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } /*@Override public boolean equals(Object o){ if(o instanceof StudentPK){ StudentPK pk = (StudentPK)o; if(this.id == pk.getId() && this.name.equals(pk.getName())){ return true; } } return false; } @Override public int hashCode(){ return this.name.hashCode(); }*/ @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + id; result = prime * result + ((name == null) ? 0 : name.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; StudentPK other = (StudentPK) obj; if (id != other.id) return false; if (name == null) { if (other.name != null) return false; } else if (!name.equals(other.name)) return false; return true; } }
2.定义实体类: Students 将主键类放到里面:
package com.zchen.hibernate.sxt.domain; public class Students { private StudentPK pk; public StudentPK getPk() { return pk; } public void setPk(StudentPK pk) { this.pk = pk; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } private int age; private String address; }
3.定义Students.hbm.xml配置文件
<?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 package="com.zchen.hibernate.sxt.domain"> <class name="Students" table="T_STUDENTS"> <composite-id name="pk" class="com.zchen.hibernate.sxt.domain.StudentPK"> <key-property name="id" column="ID"/> <key-property name="name" column="NAME"/> </composite-id> <property name="age" column="AGE"/> <property name="address" column="ADDRESS"/> </class> </hibernate-mapping>
4.定义配置文件:Hibernate.cfg.xml 略
<?xml version="1.0"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="connection.url">jdbc:mysql:///db_czbk_hibernate</property> <property name="connection.username">root</property> <property name="connection.password">1234</property> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hbm2ddl.auto">create</property> <property name="current_session_context_class">thread</property> <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <property name="show_sql">true</property> <mapping resource="com/zchen/hibernate/sxt/domain/Students.hbm.xml" /> </session-factory> </hibernate-configuration>
5.测试用例:
package com.zchen.hibernate.sxt.test; import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.AnnotationConfiguration; import org.junit.AfterClass; import org.junit.BeforeClass; import org.junit.Test; import com.zchen.hibernate.sxt.domain.StudentPK; import com.zchen.hibernate.sxt.domain.Students; public class StudentsTest { private static SessionFactory sf = null; @BeforeClass public static void beforeClass(){ try { sf = new AnnotationConfiguration().configure().buildSessionFactory(); } catch (HibernateException e) { e.printStackTrace(); } } @Test public void addStduentTest(){ StudentPK pk = new StudentPK(); pk.setId(1); pk.setName("zchen"); Students s = new Students(); s.setAge(24); s.setAddress("北京"); s.setPk(pk); Session session = sf.getCurrentSession(); session.beginTransaction(); session.save(s); session.getTransaction().commit(); } @AfterClass public static void afterClass(){ if(sf != null){ try { sf.close(); } catch (HibernateException e) { e.printStackTrace(); } } } }
输出语句:
11:32:09,818 INFO SchemaExport:226 - Running hbm2ddl schema export
11:32:09,821 DEBUG SchemaExport:242 - import file not found: /import.sql
11:32:09,821 INFO SchemaExport:251 - exporting generated schema to database
11:32:09,822 DEBUG SchemaExport:377 - drop table if exists T_STUDENTS
11:32:09,879 DEBUG SchemaExport:377 - create table T_STUDENTS (ID integer not null, NAME varchar(255) not null, AGE integer, ADDRESS varchar(255), primary key (ID, NAME))
11:32:09,953 INFO SchemaExport:268 - schema export complete
Hibernate: insert into T_STUDENTS (AGE, ADDRESS, ID, NAME) values (?, ?, ?, ?)