• 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

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  • 原文地址:https://www.cnblogs.com/zuiyirenjian/p/4023242.html
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