Hibernate 多表关联

hibernate中可以一次对多个表进行数据插入，这种插入类似

Hibernate的关联映射关系有：
多对一 ---- many-to-one
一对多 ---- one-to-many
一对一 ---- one-to-one
多对多 ---- many-to-many

比较常用的是多对一和一对一关联映射多对一关联映射：

场景：用户和组；从用户角度来看，多个用户属于一个组（多对一关联）
使用Hibernate开发的思路：先建立对象模型，把实体抽取出来。目前两个实体：用户和组两个实体，多个学生拥有同一个地址
，所有用户实体中应该有一个持有组的引用

看实体类：

package com.entity;

/**
 * Student entity. @author MyEclipse Persistence Tools
 */

public class Student implements java.io.Serializable {

    // Fields

    private Integer id;
    private String name;
    private Integer addid;

    private Adrress adss;

    // Constructors

    public Adrress getAdss() {
        return adss;
    }

    public void setAdss(Adrress adss) {
        this.adss = adss;
    }

    /** default constructor */
    public Student() {
    }

    /** full constructor */
    public Student(String name, Integer addid) {
        this.name = name;
        this.addid = addid;
    }

    // Property accessors

    public Integer getId() {
        return this.id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAddid() {
        return this.addid;
    }

    public void setAddid(Integer addid) {
        this.addid = addid;
    }

}

package com.entity;

/**
 * Adrress entity. @author MyEclipse Persistence Tools
 */

public class Adrress implements java.io.Serializable {

    // Fields

    private Integer idAdrress;
    private String detail;

    // Constructors

    /** default constructor */
    public Adrress() {
    }

    /** full constructor */
    public Adrress(String detail) {
        this.detail = detail;
    }

    // Property accessors

    public Integer getIdAdrress() {
        return this.idAdrress;
    }

    public void setIdAdrress(Integer idAdrress) {
        this.idAdrress = idAdrress;
    }

    public String getDetail() {
        return this.detail;
    }

    public void setDetail(String detail) {
        this.detail = detail;
    }

}

hibernate 映射表的内容

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Mapping file autogenerated by MyEclipse Persistence Tools -->
<hibernate-mapping>
    <class name="com.entity.Student" table="student" catalog="test">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="increment"></generator>
        </id>
        <property name="name" type="java.lang.String">
            <column name="Name" length="45" />
        </property>

        <many-to-one name="adss" column="addid" cascade="save-update" class="com.entity.Adrress"></many-to-one>
        <!-- name 属性表示Student类中的属性，column为对应的表中的和adrress表中主键关联的名称，
        也就是将address类中的主键的值作为addid的值插入表student中 -->
    </class>
</hibernate-mapping>

Spring中配置了事务，利用的是注解的方式

    <bean id="sessionFactoryt"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">

        <!-- 也可以这样配 -->
        <!-- <property name="configLocation"> <value>classpath:hibernate.cfg.xml</value>
            </property> -->
        <property name="dataSource">
            <ref bean="dataSource" />
        </property>
        <property name="hibernateProperties">
            <props>

                <prop key="hibernate.dialect">
                    org.hibernate.dialect.SQLServerDialect                     <!-- 数据库所用的sql语句 -->
                </prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">true</prop>

                <prop key="hibernate.cache.use_second_level_cache">true</prop>         <!--启用二级缓存 -->
                <prop key="hibernate.cache.use_query_cache">false</prop>              <!--是否启动查询缓存 -->
                <prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop>    <!--指定缓存类 -->

            </props>
        </property>
        <!-- <property name="packagesToScan" value="com.*" /> 为什么不起作用，别人的就可以 -->

        <!-- <property name="mappingResources"> <list> <value>com/entity/Admin.hbm.xml</value>
            <value>com/entity/Userinfo.hbm.xml</value> </list> </property> -->

        <property name="mappingDirectoryLocations">
            <list>
                <value>com/entity</value>
            </list>
        </property>
    </bean>

<bean id="tm"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactoryt" />
    </bean>

<bean id="userDao" class="com.dao.imp.UserDao">
        <property name="sessionFactory" ref="sessionFactoryt" />
    </bean>

<tx:advice id="txAdvice" transaction-manager="tm">
        <tx:attributes>
            <!-- 配置被weave织入的那些方法, 使用的传播行为和隔离级别 -->
            <tx:method name="*" propagation="REQUIRED" isolation="READ_COMMITTED" />
        </tx:attributes>
    </tx:advice>

    <!--  6.aop:config-->
    <aop:config>
        <aop:advisor advice-ref="txAdvice"
            pointcut="execution(* com.dao.imp.UserDao.*(..))" />
    </aop:config> 

 <tx:annotation-driven transaction-manager="tm" />

测试代码

ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    UserDao  ud1=(UserDao)ctx.getBean("userDao");//改成userDao就是注解方式的代理

System.out.println("OK");
ud1.insert("liu");

UserDao中的插入数据，因为没有用到接口Spring采用的CGLib代理。

public void insert(String s) {

        System.out.println("插入数据！");
        // sessionFactory.openSession().save(arg0)

            Admin adm = new Admin();
            Session sess = sessionFactory.getCurrentSession();

            Adrress ad = new Adrress();

            ad.setDetail("shan xi");

            Student st = new Student();

            st.setName("liuyu");
            st.setAdss(ad);
            sess.save(st);
            //Transaction tx = sess.beginTransaction();
            //tx.begin();
            /*Userinfo user = new Userinfo();

            System.out.println("查找数据！");

        // TODO Auto-generated method stub

    }

如果成功，就可以看到如下的语句：

插入数据！
Hibernate:
    select
        max(id)
    from
        student
Hibernate:
    select
        max(idAdrress)
    from
        adrress
插入数据！
Hibernate:
    insert
    into
        test.adrress
        (detail, idAdrress)
    values
        (?, ?)
Hibernate:
    insert
    into
        test.student
        (Name, addid, id)
    values
        (?, ?, ?)

回到数据库中也可以看到结果。

参考：http://blog.csdn.net/fengxuezhiye/article/details/7369786