springboot jpa 一对多、多对一级联查询

---

springboot jpa 一对多、多对一级联查询

 

*************************

相关注解

 

@OneToMany

public @interface OneToMany {
    Class targetEntity() default void.class;

    CascadeType[] cascade() default {};

    FetchType fetch() default FetchType.LAZY;

    String mappedBy() default "";

    boolean orphanRemoval() default false;
}

 

@ManyToOne

public @interface ManyToOne {
    Class targetEntity() default void.class;

    CascadeType[] cascade() default {};

    FetchType fetch() default FetchType.EAGER;

    boolean optional() default true;
}

 

@JoinColum

public @interface JoinColumn {

    String name() default "";
    String referencedColumnName() default "";

    boolean unique() default false;
    boolean nullable() default true;
    boolean insertable() default true;
    boolean updatable() default true;

    String columnDefinition() default "";
    String table() default "";

    ForeignKey foreignKey() default @ForeignKey(ConstraintMode.PROVIDER_DEFAULT);
}

 

 

*************************

示例：school student（一个学校有多个学生，一个学生属于一个学校）

 

******************

级联类

 

StudentMap

@Entity
@Table(name="student")
public class StudentMap {

    @Id
    @GeneratedValue(generator = "uuid2")
    private Integer id;
    private String name;
    private Integer age;

    @ManyToOne
    @JoinColumn(name = "school_id")
    private School school;

    。。。。

}

 

******************

dao层

 

StudentMapRepository

public interface StudentMapRepository extends JpaRepository {
}

 

******************

controller层

 

StudentMapController

@RestController
public class StudentMapController {

    @Autowired
    private StudentMapRepository studentMapRepository;

    @RequestMapping("/get")
    public List getAll(){
        return studentMapRepository.findAll();
    }
}

 

 

***************************

使用测试

 

localhost:8080/get