继承关系映射主要分为三种方式：
- 整个继承结构映射一张表
- 每个类映射一张表
- 每个具体子类映射一张表
整个继承结构映射一张表
建表语句：
/* 整个继承结构映射一张表 */
CREATE TABLE t_hierarchy(
id NUMBER(10) PRIMARY KEY,
owner VARCHAR2(15),
code VARCHAR2(15),
created DATE,
bankname VARCHAR2(20),
bankswift VARCHAR2(20),
credit_card_type VARCHAR2(20),
expired_month VARCHAR2(20),
expired_year VARCHAR2(20),
account_type VARCHAR2(10)
);
CREATE SEQUENCE t_hierarchy_seq
START WITH 1
INCREMENT BY 1;
BillingDetails.java 类
package com.iotek.basic.inheritance.pojo;
import java.io.Serializable;
import java.sql.Date;
public class BillingDetails implements Serializable {
private static final long serialVersionUID = -8679662269753764238L;
private Long id;
private String owner;
private String code;
private Date created;
public BillingDetails() {}
public BillingDetails(Long id, String owner, String code, Date created) {
super();
this.id = id;
this.owner = owner;
this.code = code;
this.created = created;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getOwner() {
return owner;
}
public void setOwner(String owner) {
this.owner = owner;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public Date getCreated() {
return created;
}
public void setCreated(Date created) {
this.created = created;
}
@Override
public String toString() {
return "BillingDetails [id=" + id + ", owner=" + owner + ", code=" + code + ", created=" + created + "]";
}
}
CreditCard.java 类
package com.iotek.basic.inheritance.pojo;
import java.io.Serializable;
public class CreditCard extends BillingDetails implements Serializable {
private static final long serialVersionUID = 1386209111151606704L;
private String type;
private String expMonth;
private String expYear;
public CreditCard() {}
public CreditCard(String type, String expMonth, String expYear) {
super();
this.type = type;
this.expMonth = expMonth;
this.expYear = expYear;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
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;
}
@Override
public String toString() {
return "CreditCard [type=" + type + ", expMonth=" + expMonth + ", expYear=" + expYear + "]";
}
}
BankAccount.java 类
package com.iotek.basic.inheritance.pojo;
import java.io.Serializable;
public class BankAccount extends BillingDetails implements Serializable {
private static final long serialVersionUID = -8827242347013011242L;
private String bankName;
private String bankSwift;
public BankAccount() {}
public BankAccount(String bankName, String bankSwift) {
super();
this.bankName = bankName;
this.bankSwift = bankSwift;
}
public String getBankName() {
return bankName;
}
public void setBankName(String bankName) {
this.bankName = bankName;
}
public String getBankSwift() {
return bankSwift;
}
public void setBankSwift(String bankSwift) {
this.bankSwift = bankSwift;
}
@Override
public String toString() {
return "BankAccount [bankName=" + bankName + ", bankSwift=" + bankSwift + "]";
}
}
映射文件：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.iotek.basic.inheritance.pojo">
<class name="BillingDetails" table="T_HIERARCHY" discriminator-value="BD">
<id name="id" column="ID" type="long">
<generator class="sequence">
<param name="sequence">t_billing_seq</param>
</generator>
</id>
<discriminator column="ACCOUNT_TYPE" type="string" />
<property name="owner" type="string" column="OWNER"/>
<property name="created" type="date" column="CREATED"/>
<property name="code" type="string" column="CODE"/>
<subclass name="CreditCard" discriminator-value="CC">
<property name="type" type="string" column="CREDIT_CARD_TYPE" />
<property name="expMonth" type="string" column="EXPIRED_MONTH" />
<property name="expYear" type="string" column="EXPIRED_YEAR" />
</subclass>
<subclass name="BankAccount" discriminator-value="BA">
<property name="bankName" type="string" column="BANKNAME" />
<property name="bankSwift" type="string" column="BANKSWIFT" />
</subclass>
</class>
</hibernate-mapping>
hibernate.cfg.xml配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- property 元素用于配置Hibernate中的属性 键:值 -->
<!-- hibernate.connection.driver_class : 连接数据库的驱动 -->
<property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<!-- hibernate.connection.url : 连接数据库的地址,路径 -->
<property name="connection.url">jdbc:oracle:thin:@localhost:1521:XE</property>
<!-- hibernate.connection.username : 连接数据库的用户名 -->
<property name="connection.username">guest</property>
<!-- hibernate.connection.password : 连接数据库的密码 -->
<property name="connection.password">guest</property>
<!-- show_sql: 操作数据库时,会 向控制台打印sql语句 -->
<property name="show_sql">true</property>
<!-- 数据库方言配置 org.hibernate.dialect.Oracle10gDialect (选择最短的)-->
<property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
<!-- 配置连接池最大连接数-->
<property name="hibernate.c3p0.max_size">20</property>
<!-- 配置连接池最小连接数-->
<property name="hibernate.c3p0.min_size">2</property>
<!-- 配置连接池超时时间-->
<property name="hibernate.c3p0.timeout">5000</property>
<!-- 配置连接池最大数量-->
<property name="hibernate.c3p0.max_statements">100</property>
<!-- 配置连接池空闲检索时间-->
<property name="hibernate.c3p0.idle_test_period">150</property>
<!-- 配置连接池自增数量-->
<property name="hibernate.c3p0.acquire_increment">2</property>
<!-- 配置连接池验证-->
<property name="hibernate.c3p0.validate">false</property>
<mapping resource="com/iotek/basic/pojo/Student.hbm.xml"/>
<mapping resource="com/iotek/basic/inheritance/pojo/hierarchy.hbm.xml"/>
</session-factory>
</hibernate-configuration>
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