Hibernate映射类继承之每个带有联合的具体类一张表(每个子类各一张表,共用一个父类映射文件)

pom.xml:

]<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion>
<groupId>hibernateTest</groupId>
<artifactId>hibernateTest</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>hibernateTest</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>3.3.1.GA</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-nop</artifactId>
<version>1.5.2</version>
</dependency>
<dependency>
<groupId>javassist</groupId>
<artifactId>javassist</artifactId>
<version>3.4.GA</version>
</dependency>
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1</version>
</dependency>
<dependency>
<groupId>com.oracle</groupId>
<artifactId>ojdbc14</artifactId>
<version>10.2.0.3.0</version>
<scope>runtime</scope>
</dependency>
</dependencies>
<build>
<finalName>hibernateTest</finalName>
<resources>
<resource>
<directory>src/main/resources</directory>
</resource>
<resource>
<directory>src/main/java</directory>
<excludes>
<exclude>**/*.java</exclude>
</excludes>
</resource>
</resources>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>

hibernate.cfg.xml:

]<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration
PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory name="sessionFactory">
<!-- 指定连接数据库所用的驱动 -->
<property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<!-- 指定连接数据库的url，hibernate连接的数据库名 -->
<property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:XE</property>
<property name="hibernate.connection.useUnicode">true</property>
<property name="hibernate.connection.characterEncoding">gbk</property>
<!-- 指定连接数据库的用户名 -->
<property name="hibernate.connection.username">system</property>
<!-- 指定连接数据库的密码 -->
<property name="hibernate.connection.password">password</property>
<!-- 指定连接池里最大连接数 -->
<property name="hibernate.c3p0.max_size">20</property>
<!-- 指定连接池里最小连接数 -->
<property name="hibernate.c3p0.min_size">5</property>
<!-- 指定连接池里连接的超时时长,以秒为单位 -->
<property name="hibernate.c3p0.timeout">120</property>
<!-- 指定连接池里最大缓存多少个Statement对象 -->
<property name="hibernate.c3p0.max_statements">100</property>
<!-- 每隔XX秒检查连接池里的空闲连接 ，单位是秒 -->
<property name="hibernate.c3p0.idle_test_period">120</property>
<!-- 当连接池里面的连接用完的时候，C3P0一次获取的新的连接数 -->
<property name="hibernate.c3p0.acquire_increment">2</property>
<!-- 指定数据库方言 -->
<property name="dialect">org.hibernate.dialect.OracleDialect</property>
<!-- 显示Hibernate持久化操作所生成的SQL -->
<property name="show_sql">true</property>
<!-- 将SQL脚本进行格式化后再输出 -->
<property name="hibernate.format_sql">true</property>
<!-- 罗列所有的映射文件 -->
<mapping resource="pojo/BillingDetails.hbm.xml" />
</session-factory>
</hibernate-configuration>

父类，pojo/BillingDetails.java:

]package pojo;
public class BillingDetails {
private String id;
private String owner;
public String getOwner() {
return owner;
}
public void setOwner(String owner) {
this.owner = owner;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
}

子类，pojo/BillingDetails .java:

]package pojo;
public class BankAccount extends BillingDetails {
private String account;
private String bankName;
private String swift;

public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
public String getBankName() {
return bankName;
}
public void setBankName(String bankName) {
this.bankName = bankName;
}
public String getSwift() {
return swift;
}
public void setSwift(String swift) {
this.swift = swift;
}
}

子类，pojo/CreditCard .java:

]package pojo;
public class CreditCard extends BillingDetails{
private String number;
private String expMonth;
private String expYear;

public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
public String getExpMonth() {
return expMonth;
}
public void setExpMonth(String expMonth) {
this.expMonth = expMonth;
}
public String getExpYear() {
return expYear;
}
public void setExpYear(String expYear) {
this.expYear = expYear;
}

}

映射文件, pojo/BillingDetails.hbm.xml:

]<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="pojo">
<class name="BillingDetails" abstract="true" dynamic-insert="true" dynamic-update="true">
<id name="id" column="ID" type="string">
<!-- 这里用uuid.hex生成主键 -->
<generator class="uuid.hex" />
</id>
<property name="owner" column="OWNER" type="string" />
<union-subclass name="BankAccount" table="BANK_ACCOUNT">
<!-- 如果列表与数据库关键字相同，如：ACCOUNT,我们可以用反引号把它括起来 ,反引号键就是F1下面那个键 -->
<property name="account" column="`ACCOUNT`" type="string" />
<property name="bankName" column="BANKNAME" type="string" />
<property name="swift" column="SWIFT" type="string"/>
</union-subclass>
<union-subclass name="CreditCard" table="CREDIT_CARD">
<!-- 如果列表与数据库关键字相同，如：NUMBER,我们可以用反引号把它括起来,反引号键就是F1下面那个键 -->
<property name="number" column="`NUMBER`" type="string" />
<property name="expMonth" column="EXP_MONTH" type="string" />
<property name="expYear" column="EXP_YEAR" type="string"/>
</union-subclass>
</class>
</hibernate-mapping>

util/HibernateUtil.java:

]package util;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
private static SessionFactory sessionFactory;
static{
try {
sessionFactory = new Configuration().configure().buildSessionFactory();
} catch (Throwable e) {
throw new ExceptionInInitializerError(e);
}
}
public static SessionFactory getSessionFactory(){
return sessionFactory;
}
public static void shutdown(){
getSessionFactory().close();
}
}

util/Manager.java:

]package util;
import org.hibernate.Session;
import org.hibernate.Transaction;
import pojo.BankAccount;
import pojo.CreditCard;
public class Manager {
public static void main(String[] args) {

BankAccount ba = new BankAccount();
ba.setAccount("个人帐户sssss");
ba.setBankName("付海东sssss");
ba.setOwner("fuhaidong");
ba.setSwift("aaa");

CreditCard cc = new CreditCard();
cc.setOwner("fuhaidongssss");
cc.setNumber("100000000sss");
cc.setExpYear("2010sss");
cc.setExpMonth("10");
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction transaction = session.beginTransaction();

//插入
session.save(cc);
session.save(ba);

transaction.commit();
session.close();
}
}

上例：

抽象的超类或者接口被声明为abstract="true";否则超类的实例就需要一张单独的表。

数据库标识符映射被该层中所有的具体类共用。CREDIT_CARD和BANK_ACCOUNT表都有一个ID主键列。现在数据库标识符属性必须被所有的子类共享。因而你必须把它移到BillingDetails里面，并且从CreditCard和BankAccount中把它移除。

超类(或者接口)的属性在映射文件中声明，并被所有具体的类映射继承。这样避免了相同映射的复制。

具体的子类被映射到一张表，表继承超类(或者接口)标识符和其他的属性映射。

注意，这里也是两张表：CREDIT_CARD和BANK_ACCOUNT表

CREDIT_CARD表：

ID

OWNER

NUMBER

EXP_MONTH

EXP_YEAR

BANK_ACCOUNT表：

ID

OWNER

ACCOUNT

BANKNAME

SWIFT