1.创建项目,项目名称hibernatedemo12,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Bean Comment,包名(com.mycompany.demo.bean),如图所示
4.实体Bean Comment的内容如下
package com.mycompany.demo.bean;
import java.util.Set;
public class Comment {
private int id;
private String name;
private Comment parentComment;
private Set<Comment> childrenComments;
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;
}
public Comment getParentComment() {
return parentComment;
}
public void setParentComment(Comment parentComment) {
this.parentComment = parentComment;
}
public Set<Comment> getChildrenComments() {
return childrenComments;
}
public void setChildrenComments(Set<Comment> childrenComments) {
this.childrenComments = childrenComments;
}
}
5.在src目录中创建实体Bean Comment的映射文件Comment.hbm.xml,包名(com.mycompany.demo.bean),如图所示
6.映射文件Comment.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="Comment" table="comment">
<meta attribute="class-description">
This class contains the comment detail.
</meta>
<!--
name:属性名
colum:列名
-->
<id name="id" type="int" column="id">
<!--
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" type="string" length="50" not-null="true" unique="false"/>
<!--
多对一
-->
<many-to-one name="parentComment" class="Comment" column="pid"
cascade="save-update"></many-to-one>
<!--
none:不使用级联
save-update:save(),update(),saveOrUpdate()级联操作
delete:delete()级联删除关联对象
all:对关联对象级联所有操作
delete-orphan:删除所有和当前对象解除关系的对象
all-delete-orphan:包含all和delete-orphan的所有操作
-->
<set name="childrenComments" cascade="save-update" inverse="true">
<key column="pid"/>
<one-to-many class="Comment"/>
</set>
</class>
</hibernate-mapping>
7.在src目录中创建工具类 HbnUtil,包名(com.mycompany.demo.util),如图所示
8.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();
}
}
9.在src目录中创建Hibernate的配置文件hibernate.cfg.xml,如图所示
10.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/Comment.hbm.xml"/>
</session-factory>
</hibernate-configuration>
11.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
12.TestApp测试类的内容如下
package com.mycompany.demo.bean;
import org.hibernate.Session;
import org.junit.Before;
import org.junit.Test;
import com.mycompany.demo.util.HbnUtil;
public class TestApp {
private Session session;
@Before
public void init(){
session = HbnUtil.getSession();
}
/*
* 自关联
*/
@Test
public void testOneToManyOneself(){
try {
session.beginTransaction();
Comment parentComment = new Comment();
parentComment.setName("父评论");
Comment sub1 = new Comment();
sub1.setName("小子1");
sub1.setParentComment(parentComment);
Comment sub2 = new Comment();
sub2.setName("小子2");
sub2.setParentComment(parentComment);
session.save(sub1);
session.save(sub2);
session.getTransaction().commit();
} catch (Exception e) {
session.getTransaction().rollback();
e.printStackTrace();
}
}
}