hibernate整合遗留数据库之处理主键(复合外键引用非主键)

hibernate整合遗留数据库之处理主键(复合外键引用非主键)

有些遗留schema相当复杂：外键可能是一个复合键，并且设计为引用一个复合的自然的非主键。为了映射这个，你需要按相同的名称给几个属性分组，否则无法在property-ref中给复合命名。应用<properties>元素来给映射分组,如你所见，<properties>元素不仅可以用于给几个属性命名，而且可以定义了一个多列的unique约束，或者使几个属性变成不可变。注意，对于关联映射，列的顺序仍然很重要。

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

pojo/User.java:

package pojo;import java.io.Serializable;import java.util.HashSet;import java.util.Set;public class User implements Serializable {private String id;private String name;private String password;private int age;private Set<Item> itemSet = new HashSet<Item>();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 String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public Set<Item> getItemSet() {return itemSet;}public void setItemSet(Set<Item> itemSet) {this.itemSet = itemSet;}//添加public void addItem(Item item){this.itemSet.add(item);item.setUser(this);}} 

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> <!-- 注意这里,用了unique="true",update="false" --> <properties name="foreignKey" unique="true" update="false"> <property name="name" column="NAME" type="string"/> <property name="password" column="PASSWORD" type="string"/> </properties> <property name="age" type="integer" column="AGE"/> <set name="itemSet" inverse="true" cascade="save-update"> <key property-ref="foreignKey"> <column name="NAME"/> <column name="PASSWORD"/> </key> <one-to-many class="Item"/> </set> </class> </hibernate-mapping>  

pojo/Item.java:

package pojo;import java.io.Serializable;public class Item implements Serializable {private String id;private String name;private String desc;private int price;private User user;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 String getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}} 

pojo/Item.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="Item" table="A_ITEM" dynamic-insert="true" dynamic-update="true"> <id name="id" column="ID" type="string"> <generator class="uuid.hex"/> </id> <property name="name" column="ITEMNAME" type="string"/> <property name="desc" column="DESCRIPTION" type="string"/> <property name="price" column="PRICE" type="integer"/> <!-- 注意这里使用了property-ref="name" --> <many-to-one name="user" class="User" property-ref="foreignKey"> <column name="NAME"/> <column name="PASSWORD"/> </many-to-one> </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.Item;import pojo.User;public class Manager {public static void main(String[] args) {User user = new User();user.setAge(18);user.setName("fhd");user.setPassword("kkk");Item it1 = new Item();it1.setDesc("aaaaaaa");it1.setName("item1");it1.setPrice(35);Item it2 = new Item();it2.setDesc("bbbbbbb");it2.setName("item2");it2.setPrice(12);user.addItem(it1);user.addItem(it2);Session session = HibernateUtil.getSessionFactory().openSession();Transaction transaction = session.beginTransaction();session.save(user);transaction.commit();session.close();}} 

表结构：

A_USER表：ID,NAME,AGE,PASSWORDA_ITEM表：ID,ITEMNAME,DESCRIPTIONPRICE,NAME,PASSWORD