hibernate之多态关联(多态的多对一,利用any,使用每个具体类一张表的策略)

hibernate之多态关联(多态的多对一,利用any,使用每个具体类一张表的策略)

下面以关联映射中映射的持久化类中声明了any为例，注意，这个例子是单向导航的：

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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>  

resources/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/BankAccount.hbm.xml" /> <mapping resource="pojo/CreditCard.hbm.xml" /> <mapping resource="pojo/User.hbm.xml" /> </session-factory> </hibernate-configuration>  

pojo/User.java:

package pojo; import java.io.Serializable; public class User implements Serializable { private String id; private String name; private int age; private String password; //注意这里 private BillingDetails billingDetail; public String getId() { return id; } @SuppressWarnings("unused") private void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public BillingDetails getBillingDetail() { return billingDetail; } public void setBillingDetail(BillingDetails billingDetail) { this.billingDetail = billingDetail; } }  

pojo/User.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="User" table="A_USER" dynamic-insert="true" dynamic-update="true"> <id name="id" column="ID" type="string"> <generator class="uuid.hex" /> </id> <property name="name" column="NAME" type="string"/> <property name="age" column="AGE" type="integer"/> <property name="password" column="PASSWORD" type="string"/> <!-- 注意这里 --> <any name="billingDetail" id-type="string" meta-type="string" cascade="save-update"> <meta-value class="BankAccount" value="BA"/> <meta-value class="CreditCard" value="CC"/> <column name="BILLINGDETAILS_TYPE"/> <!-- id列必须在后面 --> <column name="BILLINGDETAILS_ID"/> </any> </class> </hibernate-mapping>  

pojo/BillingDetails.java:

package pojo; import java.io.Serializable; public abstract class BillingDetails implements Serializable{ private String id; private String owner; public String getId() { return id; } @SuppressWarnings("unused") private void setId(String id) { this.id = id; } public String getOwner() { return owner; } public void setOwner(String owner) { this.owner = owner; } }  

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; } }  

pojo/CreditCard.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="CreditCard" table="A_CREDITCARD" dynamic-insert="true" dynamic-update="true"> <id name="id" column="ID" type="string"> <generator class="uuid.hex" /> </id> <property name="owner" column="OWNER" type="string"/> <property name="number" column="NUM" type="string"/> <property name="expMonth" column="EXPMONTH" type="string"/> <property name="expYear" column="EXPYEAR" type="string"/> </class> </hibernate-mapping>  

pojo/BankAccount.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; } }  

pojo/BankAccount.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="BankAccount" table="A_BANKACCOUNT" dynamic-insert="true" dynamic-update="true"> <id name="id" column="ID" type="string"> <generator class="uuid.hex" /> </id> <property name="owner" column="OWNER" type="string"/> <property name="account" column="ACCOUNT" type="string"/> <property name="bankname" column="BANKNAME" type="string"/> <property name="swift" column="SWIFT" type="string"/> </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; import pojo.User; public class Manager { public static void main(String[] args) { BankAccount ba = new BankAccount(); ba.setAccount("ba111"); ba.setBankname("ba222"); ba.setOwner("ba333"); ba.setSwift("ba444"); CreditCard cc = new CreditCard(); cc.setExpMonth("5"); cc.setExpYear("2010"); cc.setOwner("ba555"); cc.setNumber("55"); User user = new User(); user.setAge(30); user.setName("fhd"); user.setPassword("999999"); User user1 = new User(); user1.setAge(21); user1.setName("fhd33333"); user1.setPassword("33333"); user.setBillingDetail(ba); user1.setBillingDetail(cc); Session session = HibernateUtil.getSessionFactory().openSession(); Transaction transaction = session.beginTransaction(); session.save(user); session.save(user1); transaction.commit(); session.close(); } }  

表结构：

A_USER表： ID, NAME, AGE, PASSWORD, BILLINGDETAILS_ID, BILLINGDETAILS_TYPE A_BANKACCOUNT表： ID, ACCOUNT, BANKNAME, SWIFT, OWNER A_CREDITCARD表： ID, NUM, EXPMONTH, EXPYEAR, OWNER 

上例的USER表中，除了BILLINGDETAILS_ID之外，还需要BILLINGDETAILS_TYPE列，这个额外的列作用就像额外的辨别标志一样。

meta-type属性指定BILLINGDETAILS_TYPE列的hibernate类型；id-type属性指定BILLINGDETAILS_ID列的类型(CreditCard和BankAccount必须有相同的标识符类型)。

<meta-value>元素告诉hibernate如何解释BILLINGDETAILS_TYPE列的值，在这里不需要使用完整表名---可以使用你喜欢的任何值作为类型辨别标志，如：BA,CC.