Mybatis 结合Java 8 Optional查询优雅处理空指针

Mybatis 结合Optional查询优雅处理空指针

场景

结合Java 8的Optional处理查询数据，减少Controller或Service调用方法的空指针判断，让调用方代码更优雅处理数据

准备

必须mybatis-3.5.0版本以上，本人用以下maven版本的依赖

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.8</version>
</dependency>

Mapper代码

Optional <VnSku> findOne(@Param("id") Long id);

Mapper XML

<select id="findOne" resultType="com.earl.model.VnSku">
    SELECT  *
    FROM vn_sku
    WHERE id = #{id}
</select>

Service 实现调用逻辑

@Autowired
private VnSkuMapper vnSkuMapper;


public VnSku findOne(Long id)   {
    Optional < VnSku > optional = vnSkuMapper.findOne(id);
    //若数据不存在直接抛异常
    return optional.orElseThrow(()-> new ServiceException("数据不存在"));
 
}

Controller进行调用

假设获取某个商品的数量字段计算

@Autowired
private VnSkuService   vnSkuService;


@GetMapping("/sku-num/{id}")
public Response getSkuTotalNum(@PathVariable("id")Long id  )   {
    VnSku data =  vnSkuService.findOne(id);
    return Response.success().setData(data.getNum() + 5);
}