项目经验之根据查询条件分页并排序查询品牌信息

CREATE TABLE `tb_brand` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT ‘品牌id‘,
  `name` varchar(50) NOT NULL COMMENT ‘品牌名称‘,
  `image` varchar(200) DEFAULT ‘‘ COMMENT ‘品牌图片地址‘,
  `letter` char(1) DEFAULT ‘‘ COMMENT ‘品牌的首字母‘,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=325400 DEFAULT CHARSET=utf8 COMMENT=‘品牌表，一个品牌下有多个商品（spu），一对多关系‘;

CREATE TABLE `tb_category_brand` (
  `category_id` bigint(20) NOT NULL COMMENT ‘商品类目id‘,
  `brand_id` bigint(20) NOT NULL COMMENT ‘品牌id‘,
  PRIMARY KEY (`category_id`,`brand_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT=‘商品分类和品牌的中间表，两者是多对多关系‘;

@Table(name = "tb_brand")
public class Brand {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;// 品牌名称
    private String image;// 品牌图片
    private Character letter;
    // getter setter 忽略吧
}

public interface BrandMapper extends Mapper {
}

        
        tk.mybatis
            mapper-spring-boot-starter
        　　2.0.2

@SpringBootApplication
@EnableDiscoveryClient
@MapperScan("com.leyou.item.mapper") // mapper接口的包扫描
public class ItemServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(ItemServiceApplication.class, args);
    }
}

public class PageResult {
    private Long total;// 总条数
    private Integer totalPage;// 总页数
    private List items;// 当前页数据

    public PageResult() {
    }

    public PageResult(Long total, List items) {
        this.total = total;
        this.items = items;
    }

    public PageResult(Long total, Long totalPage, List items) {
        this.total = total;
        this.totalPage = totalPage;
        this.items = items;
    }

    public Long getTotal() {
        return total;
    }

    public void setTotal(Long total) {
        this.total = total;
    }

    public List getItems() {
        return items;
    }

    public void setItems(List items) {
        this.items = items;
    }

    public Long getTotalPage() {
        return totalPage;
    }

    public void setTotalPage(Long totalPage) {
        this.totalPage = totalPage;
    }
}

@RestController
@RequestMapping("brand")
public class BrandController {

    @Autowired
    private BrandService brandService;

    /**
     * 根据查询条件分页并排序查询品牌信息
     * @param key
     * @param page
     * @param rows
     * @param sortBy
     * @param desc
     * @return
     */
    @GetMapping("page")
    public ResponseEntity> queryBrandsByPage(
            @RequestParam(value = "key", required = false)String key,
            @RequestParam(value = "page", defaultValue = "1")Integer page,
            @RequestParam(value = "rows", defaultValue = "5")Integer rows,
            @RequestParam(value = "sortBy", required = false)String sortBy,
            @RequestParam(value = "desc", required = false)Boolean desc
    ){
        PageResult result = this.brandService.queryBrandsByPage(key, page, rows, sortBy, desc);
        if (CollectionUtils.isEmpty(result.getItems())){
            return ResponseEntity.notFound().build();
        }
        return ResponseEntity.ok(result);
    }
}

@Service
public class BrandService {

    @Autowired
    private BrandMapper brandMapper;

    /**
     * 根据查询条件分页并排序查询品牌信息
     *
     * @param key
     * @param page
     * @param rows
     * @param sortBy
     * @param desc
     * @return
     */
    public PageResult queryBrandsByPage(String key, Integer page, Integer rows, String sortBy, Boolean desc) {

        // 初始化example对象
        Example example = new Example(Brand.class);
        Example.Criteria criteria = example.createCriteria();

        // 根据name模糊查询，或者根据首字母查询
        if (StringUtils.isNotBlank(key)) {
            criteria.andLike("name", "%" + key + "%").orEqualTo("letter", key);
        }

        // 添加分页条件
        PageHelper.startPage(page, rows);

        // 添加排序条件
        if (StringUtils.isNotBlank(sortBy)) {
            example.setOrderByClause(sortBy + " " + (desc ? "desc" : "asc"));
        }

        List brands = this.brandMapper.selectByExample(example);
        // 包装成pageInfo
        PageInfo pageInfo = new PageInfo(brands);
        // 包装成分页结果集返回
        return new PageResult(pageInfo.getTotal(), pageInfo.getList());
    }
}