springboot使用eav模型实现curd

Spring Boot可以通过使用JPA实现EAV模型的CURD操作。以下是一些示例代码：

1. 定义EAV模型中的实体、属性和值：

@Entity
@Table(name = "entity")
public class Entity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    // 实体类型
    private String type;
    
    // 实体名称
    private String name;
    
    // ...
}

@Entity
@Table(name = "attribute")
public class Attribute {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    // 属性名称
    private String name;
    
    // ...
}

@Entity
@Table(name = "value")
public class Value {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    // 属性值
    private String value;
    
    // 属性类型
    private String type;
    
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "entity_id")
    private Entity entity;
    
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "attribute_id")
    private Attribute attribute;
    
    // ...
}

2. 定义JPA Repository：

public interface EntityRepository extends JpaRepository<Entity, Long> {
}

public interface AttributeRepository extends JpaRepository<Attribute, Long> {
}

public interface ValueRepository extends JpaRepository<Value, Long> {
    List<Value> findByEntityAndAttribute(Entity entity, Attribute attribute);
}

3. 实现CURD操作：

@Service
public class EavService {
    @Autowired
    private EntityRepository entityRepository;
    
    @Autowired
    private AttributeRepository attributeRepository;
    
    @Autowired
    private ValueRepository valueRepository;
    
    public Entity createEntity(String type, String name) {
        Entity entity = new Entity();
        entity.setType(type);
        entity.setName(name);
        return entityRepository.save(entity);
    }
    
    public Attribute createAttribute(String name) {
        Attribute attribute = new Attribute();
        attribute.setName(name);
        return attributeRepository.save(attribute);
    }
    
    public Value createValue(Entity entity, Attribute attribute, String value, String type) {
        Value val = new Value();
        val.setEntity(entity);
        val.setAttribute(attribute);
        val.setValue(value);
        val.setType(type);
        return valueRepository.save(val);
    }
    
    public List<Value> getValues(Entity entity, Attribute attribute) {
        return valueRepository.findByEntityAndAttribute(entity, attribute);
    }
    
    // ...
}

这样，我们就可以使用EAV模型来实现CURD操作了。注意，EAV模型的查询效率比较低，因此尽量避免大规模的数据查询。