hibernate实体注解 @OneToMany、@OneToOne、@ManyToOne、@ManyToMany

hibernate注解关联查询：一对多、一对一、多对一、多对多

两张表UserTest、AddressTest

 

 

一对多：@OneToMany

　　实体注解：

@Fetch(FetchMode.SUBSELECT)
@OneToMany(targetEntity = AddressTest.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "ADDRESS_USERID", referencedColumnName = "USER_ID", insertable = false, updatable = false)
 private List<AddressTest> machineMapperList;


ADDRESS_USERID字段是ADDRESS_TEST表中的关联字段
USER_ID字段位USER_TEST表中的主键

结果：UserTest{userId='H320210816161029000001', userName='张三', 
machineMapperList=[AddressTest{addressId='H320210816161316000001', userId='H320210816161029000001', addressInfo='北京市', state=1}, 
AddressTest{addressId='H320210816161350000001', userId='H320210816161029000001', addressInfo='南京市', state=1}]}

多对一：@ManyToOne

　　实体注解

@ManyToOne(targetEntity = UserTest.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "ADDRESS_USERID", referencedColumnName = "USER_ID", insertable = false, updatable = false)
private UserTest userTest

ADDRESS_USERID这个是ADDRESS_TEST表中的关联字段，这里正好于一对多的相反
USER_ID这是USER_TEST表中的主键

一对一：@OneToOne

　　实体注解

@OneToOne(targetEntity = UserTest.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "ADDRESS_USERID", referencedColumnName = "USER_ID", insertable = false, updatable = false)
 private UserTest userTest

这里的映射值同多对一的一样

多对多：@ManyToMany

@ManyToMany(targetEntity = UserTest.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinTable(name = "AU_TEST" , joinColumns = { @JoinColumn(name ="ADDRESS_ID" )}, inverseJoinColumns = { @JoinColumn(name = "USER_ID") })
private List<UserTest> userTest 

AU_TEST是中间表 

joinColumns 定义中间表与ADDRESS_TEST表的外键关系
中间表AU_TEST的ADDRESS_ID列是ADDDRESS_TEST表的主键列对应的外键列，inverseJoinColumns 属性定义了中间表与另外一端(USER_TEST)的外键关系。