因为中间表带有属性，采用的多对多映射方式 两个实体类都使用 @OneToMany( mappedBy="workDateTime")
需求：因为中间表使用两个外键作为联合主键 ，如果需要对中间表的属性进行修改，
1、一般做法
从实体类获取中间表的集合，然后遍历中间表的集合，然后修改。
WorkDateTime.getWorkDateTimeProducts()
2、一般做法很麻烦，如果条件还需要判断ProductId,则更麻烦
直接采用中间表仓库的做法
1）、建立联合主键
联合主键
public class WorkDateTimeProductKey implements Serializable{
private static final long serialVersionUID = 3586335994284551414L;
private Product product;
private WorkDateTime workDateTime;
}
2）、中间表的仓库
public interface WorkDateTimeProductRepository extends JpaRepository<WorkDateTimeProduct, Long> {
WorkDateTimeProduct findByWorkDateTime_IdAndProduct_Id(long workDateTimeId ,long productId);
}
3）由于业务上，经常会知道两个实体类的主键，就可以通过此方法：findByWorkDateTime_IdAndProduct_Id （）查询到WorkDateTimeProduct，然后直接修改
WorkDateTime_Id 其中 _的意思是 查询WorkDateTimeProduct 的 WorkDateTime 的 id属性
4）测试代码
@SpringBootTest
@RunWith(SpringRunner.class)
public class WorkDateTimeProductRepositoryTest {
@Autowired
WorkDateTimeProductRepository WorkDateTimeProductRepository;
@Test
public void findByWorkDateTimeIdAndProductIdTest(){
WorkDateTimeProduct workDateTimeProduct =WorkDateTimeProductRepository.findByWorkDateTime_IdAndProduct_Id(12l, 13l);
workDateTimeProduct.getAmount();
System.out.println(workDateTimeProduct.getAmount());
}
}
实体类1
@Entity
//@JsonIgnoreProperties(value={"workDateTimeProducts"})
public class WorkDateTime implements Serializable {
private static final long serialVersionUID = 6788933059497808914L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private long id ;
@JsonFormat(pattern="yyyy-MM-dd",timezone = "GMT+8")
@DateTimeFormat(pattern = "yyyy-MM-dd")
private Date dinnerDay;
private byte dinnerTime; // 1noon 中餐，2 evening 晚餐,3 morning
private byte state; //订餐时间段是否有效
@OneToMany( mappedBy="workDateTime")
private List<WorkDateTimeProduct> workDateTimeProducts = new ArrayList<WorkDateTimeProduct>();
private byte printAllow; //1为不可以打 2为可以打，
}
实现类2
@Entity
//@JsonIgnoreProperties(value = { "hibernateLazyInitializer", "handler" })
public class Product implements Serializable{
private static final long serialVersionUID = -3700731687896498304L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private long id ;
private String name;
private String description;
private short amount ;
private short price ;
private String productImg;
@OneToMany(mappedBy="product")
List<WorkDateTimeProduct> workDateTimeProducts =new ArrayList<WorkDateTimeProduct> ();
}
中间表
@Entity
@IdClass(WorkDateTimeProductKey.class)
public class WorkDateTimeProduct implements Serializable{
private static final long serialVersionUID = 1207408560047174539L;
@Id
@ManyToOne()
@JoinColumn(name="product_id")
private Product product;
@Id
@JsonIgnore
@ManyToOne()
@JoinColumn(name="workdatetime_id")
private WorkDateTime workDateTime;
private byte state;
private short amount ;
}