分页查询（PageHelper）

PageHelper依赖

<dependency>
   <groupId>com.github.pagehelper</groupId>
   <artifactId>pagehelper-spring-boot-starter</artifactId>
   <version>${pagehelper}</version>
</dependency>

DTO接收类

package com.sky.dto;

import lombok.Data;

import java.io.Serializable;

@Data
public class EmployeePageQueryDTO implements Serializable {

    //员工姓名
    private String name;

    //页码
    private int page;

    //每页显示记录数
    private int pageSize;

}

PageResult类

package com.sky.result;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;
import java.util.List;

/**
 * 封装分页查询结果
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class PageResult implements Serializable {

    private long total; //总记录数

    private List records; //当前页数据集合

}

Controller层

	/**
     * 员工分页查询
     * @param employeePageQueryDTO
     * @return
     */
    @GetMapping("/page")
    @ApiOperation("员工分页查询")
    public Result<PageResult> page(EmployeePageQueryDTO employeePageQueryDTO){
        log.info("员工分页查询，参数为：{}", employeePageQueryDTO);
        PageResult pageResult = employeeService.pageQuery(employeePageQueryDTO);//后续定义
        return Result.success(pageResult);
    }

Service层接口

	/**
     * 分页查询
     * @param employeePageQueryDTO
     * @return
     */
    PageResult pageQuery(EmployeePageQueryDTO employeePageQueryDTO);

Service层实现类

	/**
     * 分页查询
     *
     * @param employeePageQueryDTO
     * @return
     */
    public PageResult pageQuery(EmployeePageQueryDTO employeePageQueryDTO) {
        // select * from employee limit 0,10
        //开始分页查询
        PageHelper.startPage(employeePageQueryDTO.getPage(), employeePageQueryDTO.getPageSize());

        Page<Employee> page = employeeMapper.pageQuery(employeePageQueryDTO);//后续定义

        long total = page.getTotal();
        List<Employee> records = page.getResult();

        return new PageResult(total, records);
    }

Mapper层

	/**
     * 分页查询
     * @param employeePageQueryDTO
     * @return
     */
    Page<Employee> pageQuery(EmployeePageQueryDTO employeePageQueryDTO);

<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>