一 单一主键
assigned:由java应用程序负责生成（手工赋值）。
native：由底层数据库自动生成标示符，如果是MySQL，就是increment,如果是Oracle,就是sequence，等等。
二 通过native为MySQL生成单一主键
1 Students
import java.util.Date;
//学生类
public class Students {
/*
* JavaBeans的四点原则
* 1.必须是公有的类
* 2.提供公有的不带参数的默认的构造方法
* 3.属性私有
* 4.属性setter/getter封装
*/
private int sid; // 学号
private String sname; // 姓名
private String gender; // 性别
private Date birthday; // 出生日期
private String address; // 地址
public Students() {
}
public Students(int sid, String sname, String gender, Date birthday,
String address) {
// super();
this.sid = sid;
this.sname = sname;
this.gender = gender;
this.birthday = birthday;
this.address = address;
}
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "Students [sid=" + sid + ", sname=" + sname + ", gender="
+ gender + ", birthday=" + birthday + ", address=" + address
+ "]";
}
}
2 StudentsTest
import java.util.Date;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
//测试类
public class StudentsTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before
public void init(){
// 创建配置对象
Configuration config = new Configuration().configure();
//config.addClass(Students.class);
// 创建服务注册对象
ServiceRegistry serviceRegistery = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
// 创建会话工厂对象
sessionFactory = config.buildSessionFactory(serviceRegistery);
// 创建会话对象
session = sessionFactory.openSession();
// 开启事务
transaction = session.beginTransaction();
}
@After
public void destory(){
// 提交事务
transaction.commit();
// 关闭会话
session.close();
// 关闭会话工厂
sessionFactory.close();
}
@Test
public void testSaveStudents(){
//Students s= new Students(1,"张三丰","男",new Date(),"武当山");
Students s= new Students();
s.setSname("张三丰");
s.setGender("男");
s.setBirthday(new Date());
s.setAddress("武当山");
session.save(s);
}
}
3 Students.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="Students" table="STUDENTS">
<id name="sid" type="int">
<column name="SID" />
<generator class="native" />
id>
<property name="sname" type="java.lang.String">
<column name="SNAME" />
property>
<property name="gender" type="java.lang.String">
<column name="GENDER" />
property>
<property name="birthday" type="java.util.Date">
<column name="BIRTHDAY" />
property>
<property name="address" type="java.lang.String">
<column name="ADDRESS" />
property>
class>
hibernate-mapping>
4 hibernate.cfg.xml
xml version="1.0" encoding="UTF-8"?>
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.username">rootproperty>
<property name="hibernate.connection.password">waDY820828property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driverproperty>
<property name="hibernate.connection.url">jdbc:mysql://127.0.0.1:3306/hibernate?useUnicode=true&characterEncoding=UTF-8property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialectproperty>
<property name="show_sql">trueproperty>
<property name="format_sql">trueproperty>
<property name="hbm2ddl.auto">updateproperty>
<mapping resource="Students.hbm.xml" />
session-factory>
hibernate-configuration>
三 测试结果
连续执行两次测试用例
