03-08 05:37 阅读 119

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 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 = "A_U" , joinColumns = { @JoinColumn(name ="ADDRESS_USERID" )}, inverseJoinColumns = { @JoinColumn(name = "USER_ID") })
private List userTest


A_U是中间表
ADDRESS_USERID本表的外键
USER_ID是USER_TEST的主键

原文：https://www.cnblogs.com/javabianhua/p/15149214.html