尝试着继承关系和xdoclet使用后，对数据库面向对象的使用更近一步。
这次例子从开始到结束，都没有接触面向结构的数据库设计；
并完全在代码中以面向对象的形式来设计的。
hbn 的继承映射关系有这几种；
- 继承关系类共同使用一个表；
- 每个子类一个表(mapping全)；
- 每个具体内一个表（mapping只有父类）。
先说说3把，感觉这点最好用-》》
继承关系描述：
Animals父类 -- Bird 、Reptiles；
Animals.java
package TableBean;
/** 动物父类
* @hibernate.class
* table="animals"
*/
public class Animals {
private Integer id ;
private Integer size ;
private Integer speed;
/**
* @hibernate.id
* generator-class="increment"
*/
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
/** 动物体积大小
* @hibernate.property
*/
public Integer getSize() {
return size;
}
public void setSize(Integer size) {
this.size = size;
}
/** 动物的移动速度
* @hibernate.property
*/
public Integer getSpeed() {
return speed;
}
public void setSpeed(Integer speed) {
this.speed = speed;
}
}
Bird.java
package TableBean;
/** 在xdoeclt中声明继承表关系
* @hibernate.joined-subclass
* @hibernate.joined-subclass-key
* column="id"
*
*/
public class Bird extends Animals {
private String wings ;
private Integer leg ;
/** 鸟类翅膀描述
* @hibernate.property
* @return
*/
public String getWings() {
return wings;
}
public void setWings(String wings) {
this.wings = wings;
}
/**鸟腿描述
* @hibernate.property
* @return
*/
public Integer getLeg() {
return leg;
}
public void setLeg(Integer leg) {
this.leg = leg;
}
}
Reptiles.java
package TableBean;
/** 在xdoeclt中声明继承表关系
* @hibernate.joined-subclass
* @hibernate.joined-subclass-key
* column="id"
*/
public class Reptiles extends Animals {
private Integer leg ;
/** 爬行动物腿个数
* @hibernate.property
* @return
*/
public Integer getLeg() {
return leg;
}
public void setLeg(Integer leg) {
this.leg = leg;
}
}
ant_xdoeclt.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<!-- DO NOT EDIT -->
<!-- This file is automatically regenerated for each new XDoclet generation. -->
<!-- Any changes you make to this file will be overwritten. If you want -->
<!-- to edit this file, make a copy and rename it for your own use. -->
<project name="Hbmzj XDoclet Generation" default="_xdoclet_generation_"><property file="xdoclet-build.properties"/>
<property name="xdoclet.basedir" value="/C:/Program Files/MyEclipse/eclipse/plugins/com.genuitec.jboss.ide.eclipse.xdoclet.core_4.0.0/"/>
<path id="xdoclet.classpath"><pathelement location="E:/hibernate/Hbmzj/bin"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/rt.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/jsse.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/jce.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/charsets.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/ext/sunjce_provider.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/ext/sunpkcs11.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/ext/dnsns.jar"/>
<pathelement location="C:/Program Files/Java/jdk1.5.0_02/jre/lib/ext/localedata.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/antlr-2.7.5H3.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/asm-attrs.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/asm.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/c3p0-0.8.5.2.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/cglib-2.1.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/cleanimports.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/commons-collections-2.1.1.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/commons-logging-1.0.4.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/concurrent-1.3.2.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/connector.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/dom4j-1.6.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/ehcache-1.1.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/hibernate3.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/jaas.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/jacc-1_0-fr.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/jaxen-1.1-beta-4.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/jdbc2_0-stdext.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/jgroups-2.2.7.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/jta.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/log4j-1.2.9.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/oscache-2.1.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/proxool-0.8.3.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/swarmcache-1.0rc2.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/xerces-2.6.2.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/xml-apis.jar"/>
<pathelement location="D:/eclipse2/eclipse/plugins/org.junit_3.8.1/junit.jar"/>
<pathelement location="E:/hibernate/Hbmzj/lib/MYSQL.JAR"/>
<fileset dir="${xdoclet.basedir}">
<include name="*.jar"/>
<exclude name="*xjavadoc*.jar"/>
<include name="jdk5/*.jar"/>
</fileset>
</path>
<target name="_xdoclet_generation_" depends="N65540"/>
<target name="N65540" description="Standard Hibernate">
<taskdef name="hibernatedoclet"
classname="xdoclet.modules.hibernate.HibernateDocletTask"
classpathref="xdoclet.classpath"/>
<hibernatedoclet excludedTags="@version,@author,@todo,@see"
destDir="src"
addedTags="@xdoclet-generated at ${TODAY},@copyright The XDoclet Team,@author XDoclet,@version ${version}" >
<fileset dir="src" includes="**/*.java" >
</fileset>
<hibernate>
</hibernate>
</hibernatedoclet>
</target>
</project>
ant运行 后得到 Animals.hbm.xml 文件
使用 hbn工具 hbn2ddl 后
mysql> desc Animals;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| id | int(11) | | PRI | 0 | |
| size | int(11) | YES | | NULL | |
| speed | int(11) | YES | | NULL | |
+-------+---------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql> desc reptiles;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| id | int(11) | | PRI | 0 | |
| leg | int(11) | YES | | NULL | |
+-------+---------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> desc bird;
+-------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id | int(11) | | PRI | 0 | |
| wings | varchar(255) | YES | | NULL | |
| leg | int(11) | YES | | NULL | |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
添加测试数据：
mysql> select * from bird;
+----+-------+------+
| id | wings | leg |
+----+-------+------+
| 1 | 2G | 2 |
+----+-------+------+
1 row in set (0.00 sec)
mysql> select * from Animals;
+----+------+-------+
| id | size | speed |
+----+------+-------+
| 1 | 1 | 9 |
| 2 | 6 | 2 |
+----+------+-------+
2 rows in set (0.00 sec)
mysql> select * from Reptiles;
+----+------+
| id | leg |
+----+------+
| 2 | 4 |
+----+------+
1 row in set (0.00 sec)
测试
public class TestJc extends TestCase {
public void testJC() throws Exception {
Session session= HbnFactory.currentSession();
Transaction tr = session.beginTransaction();
//1
Animals aa = (Animals)session.load(Animals.class,1);
System.out.println(aa);
//2
Bird bb = (Bird) session.load(Bird.class,1);
System.out.println(bb);
//3
Object obj = session.createQuery(" from Animals ").list();
System.out.println(obj);
tr.commit();
HbnFactory.closeSession();
}
}
结果：
//1
Hibernate: select animals0_.id as id0_, animals0_.size as size0_0_, animals0_.speed as speed0_0_, animals0_1_.wings as wings1_0_, animals0_1_.leg as leg1_0_, animals0_2_.leg as leg2_0_, case when animals0_1_.id is not null then 1 when animals0_2_.id is not null then 2 when animals0_.id is not null then 0 end as clazz_0_ from animals animals0_ left outer join Bird animals0_1_ on animals0_.id=animals0_1_.id left outer join Reptiles animals0_2_ on animals0_.id=animals0_2_.id where animals0_.id=?
TableBean.Bird@5e176f
//2
TableBean.Bird@5e176f
//3
Hibernate: select animals0_.id as id, animals0_.size as size0_, animals0_.speed as speed0_, animals0_1_.wings as wings1_, animals0_1_.leg as leg1_, animals0_2_.leg as leg2_, case when animals0_1_.id is not null then 1 when animals0_2_.id is not null then 2 when animals0_.id is not null then 0 end as clazz_ from animals animals0_ left outer join Bird animals0_1_ on animals0_.id=animals0_1_.id left outer join Reptiles animals0_2_ on animals0_.id=animals0_2_.id
[TableBean.Bird@5e176f, TableBean.Reptiles@2c1e6b, TableBean.Reptiles@811c88]