springData表关系：一对多

一、编写实体类进行表关联

1、在一张表的关联属性上添加@OneToMany注解（关联属性用来记录多的一方的信息，是个集合，一般用set）

2、在另一个实体类的关联属性上添加@ManyToOne注解和 @JoinColumn(name="custid",referencedColumnName = "cust_id")注解

二、编写dao：两个dao都继承JpaRepository<实体类名，主键属性>

三、编写测试类（用法）

package cn.lijun.jpa;

import cn.lijun.jpa.dao.CustomerDao2;
import cn.lijun.jpa.dao.LinkManDao;
import cn.lijun.jpa.entity.Customer2;
import cn.lijun.jpa.entity.LinkMan;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.annotation.Commit;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.annotation.Transactional;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class OneToManyTest {
    @Autowired
    private CustomerDao2 customerDao2;
    @Autowired
    private LinkManDao linkManDao;
    @Test
    @Transactional
    @Commit
    public void addCustomer2(){
        // 1每个实体类 创建dao
        //2创建Customer2对象
        Customer2 customer2 = new Customer2();
        customer2.setCustName("张无忌");
        customer2.setCustAddress("光明顶");
        customer2.setCustLevel("教主");
        //3创建LinkMan对象
        LinkMan linkMan1 = new LinkMan();
        linkMan1.setLkmName("赵敏");
        linkMan1.setLkmMobile("13111111");
        LinkMan linkMan2 = new LinkMan();
        linkMan2.setLkmName("小昭");
        linkMan2.setLkmMobile("13166661");
        LinkMan linkMan3 = new LinkMan();
        linkMan3.setLkmName("灭绝师太");
        linkMan3.setLkmMobile("13166661111");
        // 4 配置客户和联系人之间的关系
        customer2.getLinkMEN().add(linkMan1);
        customer2.getLinkMEN().add(linkMan2);
        customer2.getLinkMEN().add(linkMan3);
        linkMan1.setCustomer(customer2);
        linkMan2.setCustomer(customer2);
        linkMan3.setCustomer(customer2);
        //5 使用dao 把数据写入数据库
        customerDao2.save(customer2);
        linkManDao.save(linkMan1);
        linkManDao.save(linkMan2);
        linkManDao.save(linkMan3);
    }
}