【SpringBoot】分页查询

1. Controller

    @ApiOperation("分页查询")@GetMapping("/page")public Result<PageResult> pageResultResult(EmployeePageQueryDTO employeePageQueryDTO) {System.out.println(employeePageQueryDTO.toString());PageResult pageResult = employeeService.pageQuery(employeePageQueryDTO);return Result.success(pageResult);}

2. Service

  这里使用PageHelper协助完成分页查询操作。PageHelper基于ThreadLocal实现，ThreadLocal会保存page和pageSize，在执行sql语句时候自动填补相应的limit语句。

    @Overridepublic PageResult pageQuery(EmployeePageQueryDTO employeePageQueryDTO) {PageHelper.startPage(employeePageQueryDTO.getPage(), employeePageQueryDTO.getPageSize());Page<Employee> employeePage = employeeMapper.pageQuery(employeePageQueryDTO);val total = employeePage.getTotal();val result = employeePage.getResult();return new PageResult(total, result);}

3. Mapper

  这里使用 where 标签设置查询条件，使用 if 标签判断 name 字段是否为空。这里对于 name 字段使用模糊查询进行匹配，使用 concat 进行连接。

    <select id="pageQuery" resultType="com.sky.entity.Employee">select * from employee<where><if test="name!=null and name!=''">and name like concat('%', #{name}, '%')</if></where>order by create_time desc</select>