1.创建项目,项目名称hibernatedemo28,目录结构如图所示

2.在项目中创建lib目录存储jar文件,目录结构如图所示

3.在src目录中创建实体类Forum,包名(com.mycompany.demo.bean),如图所示

4.实体类Forum的内容如下

package com.mycompany.demo.bean;import java.util.Set;public class Forum {private int fid;private String name;private Set<ForumPost> forumPosts;public int getFid() {return fid;}public void setFid(int fid) {this.fid = fid;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Set<ForumPost> getForumPosts() {return forumPosts;}public void setForumPosts(Set<ForumPost> forumPosts) {this.forumPosts = forumPosts;}
}

5.在src目录中创建实体类Forum的映射文件Forum.hbm.xml,包名(com.mycompany.demo.bean),如图所示

6.映射文件Forum.hbm.xml的内容如下

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!--package:指定<class/>所在的包 -->
<hibernate-mapping package="com.mycompany.demo.bean"><!--name:类名table:表名 catalog:数据库名称,默认为hibernate.cfg.xml中配置的数据库名称--><class name="Forum" table="forum" lazy="false"><meta attribute="class-description">This class contains the forum detail. </meta><!--name:属性名colum:列名 --><id name="fid" type="int" column="fid"><!--increment:hibernate维护主键值identity:数据库自增长sequence:序列native:根据不同的数据库选择生成策略uuid:通过UUID算法生成,实际使用较多assigned:手工设置--><generator class="native"/></id><!--length:字节长度type:字段类型,支持java和hibernate类型not-null:非空约束unique:唯一性约束--><property name="name" column="name" /><!--lazy:false:直接加载true:延迟加载extra:特别延迟加载fetchjoin:迫切左外连接select:普通select查询subselect :子查询方式--><set name="forumPosts"><key column="fid"/><one-to-many class="ForumPost"/></set></class>
</hibernate-mapping>

7.在src目录中创建实体类ForumPost,包名(com.mycompany.demo.bean),如图所示

8.实体类ForumPost的内容如下

package com.mycompany.demo.bean;public class ForumPost {private int pid;private String subject;private Forum forum;public int getPid() {return pid;}public void setPid(int pid) {this.pid = pid;}public String getSubject() {return subject;}public void setSubject(String subject) {this.subject = subject;}public Forum getForum() {return forum;}public void setForum(Forum forum) {this.forum = forum;}
}

9.在src目录中创建实体类ForumPost的映射文件ForumPost.hbm.xml,包名(com.mycompany.demo.bean),如图所示

10.映射文件ForumPost.hbm.xml的内容如下

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!--package:指定<class/>所在的包 -->
<hibernate-mapping package="com.mycompany.demo.bean"><!--name:类名table:表名 catalog:数据库名称,默认为hibernate.cfg.xml中配置的数据库名称--><class name="ForumPost" table="forumpost"><meta attribute="class-description">This class contains the forumpost detail. </meta><!--name:属性名colum:列名 --><id name="pid" type="int" column="pid"><!--increment:hibernate维护主键值identity:数据库自增长sequence:序列native:根据不同的数据库选择生成策略uuid:通过UUID算法生成,实际使用较多assigned:手工设置--><generator class="native"/></id><!--length:字节长度type:字段类型,支持java和hibernate类型not-null:非空约束unique:唯一性约束--><property name="subject" column="subject" type="string" length="50" not-null="true" unique="false"/><!--name:关联属性 column:关联属性在数据库对应的字段class:关联属性所对应的类型--><many-to-one name="forum" class="Forum" column="fid" cascade="save-update" fetch="select" lazy="proxy"/></class><query name="queryAll">from Forum f left outer join fetch f.forumPosts</query>
</hibernate-mapping>

11.在src目录中创建工具类 HbnUtil,包名(com.mycompany.demo.util),如图所示

12.工具类 HbnUtil的内容如下

package com.mycompany.demo.util;import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;public class HbnUtil {private static SessionFactory sessionFactory;public static Session getSession(){if(sessionFactory == null || sessionFactory.isClosed()){sessionFactory = new Configuration().configure().buildSessionFactory();}return sessionFactory.getCurrentSession();}
}

13.在src目录中创建Hibernate的配置文件hibernate.cfg.xml,如图所示

14.Hibernate的配置文件hibernate.cfg.xml的内容如下

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration SYSTEM
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"><hibernate-configuration><session-factory><!-- 方言,可以从Hibernate核心jar(hibernate-core-x.x.x.Finall.jar)文件中的or.hibernate.dialect包中找到相应的类,类的全名就是 --><property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property><!-- 驱动 --><property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property><!-- 数据库连接地址 --><property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property><!-- 用户名 --><property name="hibernate.connection.username">root</property><!-- 密码 --><property name="hibernate.connection.password"></property><!--create:每次都新创建,如果存在就删除create-drop:创建新表,sessionFactory关闭,表会删除update :表字段增加,会同步,字段减少不同步,数据改变会同步修改--><property name="hibernate.hbm2ddl.auto">update</property><!-- 输出sql --><property name="hibernate.show_sql">true</property><!-- 格式化sql --><property name="hibernate.format_sql">true</property><!-- 事务环境一个线程对一个事务thread:本地事务环境jta:分布式事务环境SpringSessionContext:用于ssh整合--><property name="hibernate.current_session_context_class">thread</property>      <!-- 使用c3p0数据源 --><property name="hibernate.connection.provider_class">org.hibernate.c3p0.internal.C3P0ConnectionProvider</property> <!-- List of XML mapping files --><mapping resource="com/mycompany/demo/bean/Forum.hbm.xml"/><mapping resource="com/mycompany/demo/bean/ForumPost.hbm.xml"/>
</session-factory>
</hibernate-configuration>

15.在项目中创建test目录存储测试文件,文件名称TestApp,包名(com.mycompany.demo.bean),目录结构如图所示

16.TestApp测试类的内容如下

package com.mycompany.demo.bean;import java.util.HashSet;
import java.util.List;
import java.util.Set;import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.sql.JoinType;
import org.junit.Before;
import org.junit.Test;import com.mycompany.demo.util.HbnUtil;public class TestApp {private Session session;@Beforepublic void init(){session = HbnUtil.getSession();}/** 一对多双向关联-添加* 需要设置Forum.hbm.xml中的Set属性为cascade="all"*/@Testpublic void testOneToManyAdd(){try {session.beginTransaction();ForumPost forumPost1 = new ForumPost();forumPost1.setSubject("A");ForumPost forumPost2 = new ForumPost();forumPost2.setSubject("B");Set<ForumPost> forumPosts = new HashSet<ForumPost>();forumPosts.add(forumPost1);forumPosts.add(forumPost2);Forum forum = new Forum();forum.setName("foruma");forum.setForumPosts(forumPosts);session.save(forum);session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();}}/** 多对一双向关联-fetch="select",lazy="proxy",在一的一方的class标签中添加lazy="false"属性*/@Testpublic void testFetchForSelect(){try {session.beginTransaction();ForumPost forumPost = session.get(ForumPost.class, 10);Forum forum = forumPost.getForum();System.out.println(forum.getFid());System.out.println(forum.getName());session.getTransaction().commit();} catch (Exception e) {session.getTransaction().rollback();e.printStackTrace();}}
}

本文转自 素颜猪 51CTO博客，原文链接:http://blog.51cto.com/suyanzhu/1913088