Hibernate 学习代码/笔记 (一)
业余时间学习下Hibernate.....
Hibernate的概念和作用就不废话了..百度都有..
Hibernate和JDBC比较:
使用JDBC有以下缺点:
1.需要编写大量的SQL语句
2.需要大量的?参数赋值
3.需要将ResultSet结果集合转换成实体对象
4.SQL中包含特有函数,无法移植
使用Hibernate可以解决以上问题:
1.自动生成SQL
2.自动给?赋值
3.自动将ResultSet结果集转换为实体对象
4.采用一致的方法对数据库操作,移植性好
Hibernate和MyBatis比较:
共性:
1.对JDBC进行了封装
2.采用ORM框架思想解决了Entity和数据库的映射问题
MyBatis:
1.MyBaits采用SQL与Entity映射,对JDBC封装程度较轻
2.MyBatis自己写SQL,更具有灵活性
Hibernate:
1.Hibernate采用数据库与Entity映射,对JDBC封装比较重.
2.Hibernate自动生成SQL,对于基本的操作,开发效率较高.
ORM思想:
ORM:Object Relation Mapping ,即对象关系映射,指的是Java对象与关系数据库之间的映射
ORM思想:就是将对象与数据库数据进行相互转换的思想,不同的框架技术实现ORM的手段不同,但更多的采用配置+反射的方式来实现ORM
创建工程和引JAR包什么的就不废话了...
具体的流程...
1.创建实体类
2.提供User.hbm.xml文件
3.将User.hbm.xml文件加入到hibernate.cfg.xml文件中
4.编写工具类ExportDB.java，将hbm生成ddl,也就是hbm2ddl
5.建立客户端类Client，添加用户数据到mySQL
先来一个结构图吧
好了..下面上代码
首先是实体类..
package com.hibernate.entity;
import java.util.Date;
public class Students {
private int sid;
private String sname;
private String gender;
private Date birthday;
private String 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 + "]";
}
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 Students() {
// super();
}
}
然后是hibernate 的配置文件 hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="connection.username">root</property> <!-- 数据库用户名 --> <property name="connection.password">1234</property> <!-- 数据库密码 --> <property name="connection.driver_class">com.mysql.jdbc.Driver</property><!-- 数据库驱动 --> <!-- 数据库地址 --> <property name="connection.url">jdbc:mysql://localhost:3306/test?user=root&password=1234&useUnicode=true&characterEncoding=UTF-8</property> <property name="dialect">org.hibernate.dialect.MySQLDialect</property><!-- mysql 数据库方言 --> <property name="show_sql">true</property> <property name="format_sql">true</property> <property name="hbm2ddl.auto">create</property> <mapping resource="com/hibernate/entity/Students.hbm.xml"/> </session-factory> </hibernate-configuration>
关于映射文件...我用的是Eclipse,安装了hibernate插件以后,自动生成的...
(话说新版的Eclipse启动的图片挺好看的...)
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2015-12-19 23:24:01 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="com.hibernate.entity.Students" table="STUDENTS">
<id name="sid" type="int">
<column name="SID" />
<generator class="assigned" />
</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>
然后写一个测试方法 StudentsTest
package com.test;
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;
import com.hibernate.entity.Students;
//测试类
public class StudentsTest {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
@Before //初始化
public void init(){
//创建配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = (ServiceRegistry) new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//创建会话工厂对象
sessionFactory = config.buildSessionFactory(serviceRegistry);
//创建会话对象
session = sessionFactory.openSession();
//开启事务
transaction = session.beginTransaction();
}
@After //释放资源
public void destory(){
transaction.commit(); //提交
session.close(); //关闭会话
sessionFactory.close(); //关闭会话工厂
}
@Test
public void testSaveStudents(){
try{
Students st = new Students();
st.setSid(1);
st.setSname("小王");
st.setGender("男");
st.setBirthday(new Date());
st.setAddress("中南海");
session.save(st);
}catch(Exception e){
e.printStackTrace();
}
}
}
然后就可以欢乐的跑起来了....
因为数据库字符集问题...数据库的图片我就不传了..都是乱码...
关于hibernate.cfg.xml的配置,以后再说...
这个是根据慕课网学习后写出来的例子...感谢慕课网...
更新于2015-12-24
完整的hibernate单表增删查改
entity实体类
package com.hibernate.entity;
import java.sql.Date;
import java.sql.Timestamp;
public class Emp {
private Integer id;
private String name;
private Integer age;
private Double salary;
private Boolean marry;
private Date birthday;
private Timestamp lastLoginTime;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Double getSalary() {
return salary;
}
public void setSalary(Double salary) {
this.salary = salary;
}
public Boolean getMarry() {
return marry;
}
public void setMarry(Boolean marry) {
this.marry = marry;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public Timestamp getLastLoginTime() {
return lastLoginTime;
}
public void setLastLoginTime(Timestamp lastLoginTime) {
this.lastLoginTime = lastLoginTime;
}
@Override
public String toString() {
return "Emp [id=" + id + ", name=" + name + ", age=" + age
+ ", salary=" + salary + ", marry=" + marry + ", birthday="
+ birthday + ", lastLoginTime=" + lastLoginTime + "]";
}
public Emp(Integer id, String name, Integer age, Double salary,
Boolean marry, Date birthday, Timestamp lastLoginTime) {
// super();
this.id = id;
this.name = name;
this.age = age;
this.salary = salary;
this.marry = marry;
this.birthday = birthday;
this.lastLoginTime = lastLoginTime;
}
public Emp() {
// super();
}
}
实体类配置文件
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 学生的对象关系映射 -->
<hibernate-mapping>
<class name="com.hibernate.entity.Emp" table="emp"> <!-- 配置实体类 和 表的关系 -->
<id name="id" type="integer" column="id"> <!-- 配置主键属性和字段的关系 -->
<generator class="sequence"> <!-- 用来指明主键的生成方式 -->
<param name="sequence">emp_seq</param> <!-- 指定用于生成主键的sequence -->
</generator>
</id>
<property name="name" type="string" column="name"></property>
<property name="age" type="integer" column="age"></property>
<property name="salary" type="double" column="salary"></property>
<property name="birthday" type="date" column="birthday"></property>
<property name="lastLoginTime" type="timestamp" column="last_Login_Time"></property>
<property name="marry" type="yes_no" column="marry"></property>
</class>
</hibernate-mapping>
<!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 > <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property> <!-- 数据库地址 --> <property name="connection.username">Simba</property> <!-- 数据库用户名 --> <property name="connection.password">Simba</property> <!-- 数据库密码 --> <property name="connection.driver_class">oracle.jdbc.OracleDriver</property> <!-- 数据库驱动 --> <property name="dialect">org.hibernate.dialect.OracleDialect</property> <!-- mysql 数据库方言 --> <property name="show_sql">true</property> <property name="format_sql">true</property> <property name="hbm2ddl.auto">update</property> <mapping resource="com/hibernate/entity/Emp.hbm.xml"/> </session-factory> </hibernate-configuration>
hibernate 配置文件
<!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 > <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property> <!-- 数据库地址 --> <property name="connection.username">Simba</property> <!-- 数据库用户名 --> <property name="connection.password">Simba</property> <!-- 数据库密码 --> <property name="connection.driver_class">oracle.jdbc.OracleDriver</property> <!-- 数据库驱动 --> <property name="dialect">org.hibernate.dialect.OracleDialect</property> <!-- mysql 数据库方言 --> <property name="show_sql">true</property> <property name="format_sql">true</property> <property name="hbm2ddl.auto">update</property> <mapping resource="com/hibernate/entity/Emp.hbm.xml"/> </session-factory> </hibernate-configuration>
获取session的工具类
package com.hibernate.util;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class HibernateUtil {
private static SessionFactory sessionFactory;
//加载Hibernate主配置
static {
//创建配置对象
Configuration config = new Configuration().configure();
//创建服务注册对象
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
//创建会话工厂对象
sessionFactory = config.buildSessionFactory(serviceRegistry);
}
//获取session
public static Session getSession(){
return sessionFactory.openSession();
}
}
测试代码
package com.hibernate.test;
import java.sql.Date;
import java.sql.Timestamp;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
import com.hibernate.entity.Emp;
import com.hibernate.util.HibernateUtil;
public class EmpTest {
private Session session;
private HibernateUtil hibernateUtil;
/**
* 添加
* @throws Exception
*/
@Test
public void add() throws Exception {
Emp emp = new Emp();
emp.setName("小王");
emp.setAge(18);
emp.setMarry(false);
emp.setSalary(8000.0);
emp.setBirthday(Date.valueOf("1993-1-1"));
emp.setLastLoginTime(new Timestamp(System.currentTimeMillis()));
session = hibernateUtil.getSession();
// 开启事务
Transaction transaction = (Transaction) session.beginTransaction();
try {
session.save(emp);
transaction.commit();
} catch (Exception e) {
e.printStackTrace();
transaction.rollback();
} finally {
session.close();
}
}
/**
* 根据ID查找
*/
@Test
public void findById() {
session = hibernateUtil.getSession();
Emp emp = (Emp) session.get(Emp.class, 1);
System.out.println(emp.getName() + " " + emp.getAge());
session.close();
}
/**
* 修改更新
*/
@Test
public void update() {
session = hibernateUtil.getSession();
Transaction transaction = session.beginTransaction();
Emp emp = (Emp) session.get(Emp.class, 1);
try {
emp.setName("大王");
emp.setAge(99);
session.update(emp);
transaction.commit();
} catch (Exception e) {
e.printStackTrace();
transaction.rollback();
} finally {
if (session != null) {
session.close();
}
}
}
/**
* 删除
*/
@Test
public void delete(){
session = hibernateUtil.getSession();
Transaction transaction = session.beginTransaction();
Emp emp = (Emp)session.get(Emp.class, 2);
try{
session.delete(emp);
transaction.commit();
}catch(Exception e){
e.printStackTrace();
transaction.rollback();
}finally{
session.close();
}
}
/**
* 查询所有
*/
@Test
public void findAll(){
session = hibernateUtil.getSession();
String hsql = "from Emp";
Query query = session.createQuery(hsql);
List<Emp> listEmp = query.list();
for (Emp emp : listEmp) {
System.out.println(emp.getName());
}
session.close();
}
}