Hibernate_01_初体验

hibernate开发的基本步骤：

编写配置文档hibernate.cfg.xml；
编写实体类；
生成对应实体类的映射文件并添加到配置文档中；
调用hibernate API进行测试。

Hibernate的一个小例子（慕课网教程整理的代码）：

首先在eclipse--help--Eclipse MarketPlace中搜索“jboss Tool”

导入hibernate核心jar包、Junit包。

创建一个java类：

 1 package com.imooc.hibernate;

 2

 3 import java.util.Date;

 4

 5 public class Students {

 6

 7     private int sid;

 8     private String sname;

 9     private String gender;

10     private Date birthday;

11     private String address;

12

13     public Students(int sid, String sname, String gender, Date birthday, String address) {

14         super();

15         this.sid = sid;

16         this.sname = sname;

17         this.gender = gender;

18         this.birthday = birthday;

19         this.address = address;

20     }

21

22     @Override

23     public String toString() {

24         return "Students [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday

25                 + ", address=" + address + "]";

26     }

27

28     public int getSid() {

29         return sid;

30     }

31

32     public void setSid(int sid) {

33         this.sid = sid;

34     }

35

36     public String getSname() {

37         return sname;

38     }

39

40     public void setSname(String sname) {

41         this.sname = sname;

42     }

43

44     public String getGender() {

45         return gender;

46     }

47

48     public void setGender(String gender) {

49         this.gender = gender;

50     }

51

52     public Date getBirthday() {

53         return birthday;

54     }

55

56     public void setBirthday(Date birthday) {

57         this.birthday = birthday;

58     }

59

60     public String getAddress() {

61         return address;

62     }

63

64     public void setAddress(String address) {

65         this.address = address;

66     }

67 }

点击项目名，右键new--other--自动生成类的配置文件：

 <?xml version="1.0"?>

 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

 <!-- Generated 2017-5-23 0:24:09 by Hibernate Tools 3.5.0.Final -->

 <hibernate-mapping>

     <class name="com.imooc.hibernate.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>

生成hibernate配置文件：

 <?xml version="1.0" encoding="UTF-8"?>

 <!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.username">root</property>

         <property name="connection.password">root</property>

         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

         <property name="connection.url">jdbc:mysql://localhost:3306/hibernate?useUnicode=true&amp;characterEncoding=UTF-8</property>

         <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

         <!-- 是否将sql语句打印到控制台，编码阶段便于测试，建议设为true -->

         <property name="show_sql">true</property>

         <!-- 是否将sql语句进行排版，建议设为true -->

         <property name="format_sql">true</property>

         <!-- 生成表结构的策略。create是如果之前有表结构，先删除表结构再重建；

             update：原有的基础上更新；

             create-drop：先删除表结构再重建

             validate：与原表进行验证，如果和原表表结构不同，则不进行创建。

             一般使用create和update

          -->

         <property name="hbm2ddl.auto">create</property>

         <mapping resource="com/imooc/hibernate/Students.hbm.xml"/>

     </session-factory>

 </hibernate-configuration>

写StudentsTest.java文件：

 package com.icoom.test;

 import static org.junit.Assert.fail;

 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.imooc.hibernate.Students;

 public class StudentsTest {

     private SessionFactory sessionFactory;

     private Session session;

     private Transaction transaction;

     @Before

     public void init() {

         // 1.创建配置对象

         Configuration config = new Configuration().configure();

         // 2.创建服务注册对象

         ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();

         // 3.创建会话工厂对象

         sessionFactory = config.buildSessionFactory(serviceRegistry);

         // 会话对象

         session = sessionFactory.openSession();

         // 开启事务

         transaction = session.beginTransaction();

     }

     @After

     public void destory() {

         transaction.commit();

         session.close();

         sessionFactory.close();

     }

     @Test

     public void testSaveStudents() {

         // 生成学生对象

         Students s = new Students(1, "老张", "男", new Date(), "山东");

         session.save(s);//保存对象进入数据库

     }

 }

使用Junit执行，然后在数据库中就会看到新建的表结构和插入的数据。

hibernate.cfg.xml文件中的<property name="hbm2ddl.auto">create</property>指定由hibernate新建表。

-------------------------------------

以上是对hibernate的配置文件元素的作用和hibernate的用法做一个简单的了解，一开始学习新技术要保持不求甚解，先快速入门以避免从入门到放弃。等达到一定熟练度再深入了解其原理。因此强烈推荐慕课网的教程，先快速了解再深入学习。

巴特西

Hibernate_01_初体验

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