分页查询

PageInfo(github)

  导入依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.2</version>
</dependency>

  controller

@ApiOperation("分页查询后台菜单")
    @RequestMapping(value = "/list/{parentId}", method = RequestMethod.GET)
    @ResponseBody
    public CommonResult<CommonPage<UmsMenu>> list(@PathVariable Long parentId,
                                                  @RequestParam(value = "pageSize", defaultValue = "5") Integer pageSize,
                                                  @RequestParam(value = "pageNum", defaultValue = "1") Integer pageNum) {
        List<UmsMenu> menuList = menuService.list(parentId, pageSize, pageNum);
        PageInfo<UmsMenu> pageInfo = new PageInfo<>(menuList);
        return CommonResult.success(pageInfo);
    }

  service

@Override
    public List<UmsMenu> list(Long parentId, Integer pageSize, Integer pageNum) {
        PageHelper.startPage(pageNum, pageSize);
        UmsMenuExample example = new UmsMenuExample();
        example.setOrderByClause("sort desc");
        example.createCriteria().andParentIdEqualTo(parentId);
        // 此处查询的结果集为第pageNum的数据
        return menuMapper.selectByExample(example);
    }

Page(MybatisPlus)

  配置类

/**
 * 配置MP的分页插件
 */
@Configuration
public class MybatisPlusConfig {

    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }
}

  controller

    @GetMapping("/list")
    public Result<Page> pageDemo(int pageNum, int pageSize) {
        // 构造分页构造器
        Page pageInfo = new Page(pageNum, pageSize);
        // 构造条件构造器
        LambdaQueryWrapper<Employee> queryWrapper = new LambdaQueryWrapper<>();
        queryWrapper.orderByDesc(Employee::getUpdateTime);
        // 执行查询（page是内部函数）
        employeeService.page(pageInfo, queryWrapper);
        return Result.success(pageInfo);
    }