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