解决mybatis-plus不能俩表联查分页之手动写分页

public class MyPageHelper {// 调用pageInfo插件内的方法 开启分页 需要传入一个起始页的值和每页显示的条数public static void startPage(PageRequest pageRequest) {PageHelper.startPage(pageRequest.getPageNum(),pageRequest.getPageSize());}// 封装结果集public static PageResult getPageResult(List content) {// 创建分页对象 将结果传入对象中 pageInfo对象中生成信息PageInfo pageInfo = new PageInfo<>(content);// 创建返回的对象PageResult pageResult = new PageResult();// 获取总页数pageResult.setTotal(pageInfo.getTotal());// 获取结果pageResult.setContent(pageInfo.getList());// 获取总页数pageResult.setPages(pageInfo.getPages());// 获取起始页数pageResult.setPageNum(pageInfo.getPageNum());// 获取每页显示的条数pageResult.setPageSize(pageInfo.getPageSize());// 返回结果return pageResult;}}

public class PageRequest {/***页数*/private int pageNum;/*** 每页的信息的个数*/private int pageSize;public PageRequest() {}public PageRequest(int pageNum, int pageSize) {this.pageNum = pageNum;this.pageSize = pageSize;}/*** 获取* @return pageNum*/public int getPageNum() {return pageNum;}/*** 设置* @param pageNum*/public void setPageNum(int pageNum) {this.pageNum = pageNum;}/*** 获取* @return pageSize*/public int getPageSize() {return pageSize;}/*** 设置* @param pageSize*/public void setPageSize(int pageSize) {this.pageSize = pageSize;}public String toString() {return "PageRequest{pageNum = " + pageNum + ", pageSize = " + pageSize + "}";}
}

public class PageResult {/***页数*/private int pageNum;/*** 每页的信息的个数*/private int pageSize;/*** 总条数*/private Long total;/*** 总页数*/private int pages;/*** 结果集*/private List<?> content;public PageResult() {}public PageResult(int pageNum, int pageSize, Long total, int pages, List<?> content) {this.pageNum = pageNum;this.pageSize = pageSize;this.total = total;this.pages = pages;this.content = content;}/*** 返回结果调用的方法*/public static PageResult getPageResult(List content,PageRequest pageRequest,Long total) {// 创建返回的对象PageResult pageResult = new PageResult();// 将分页后查询到的结果放入对象中pageResult.setContent(content);// 将起始页放入对象中pageResult.setPageNum(pageRequest.getPageNum());// 将每页显示的条数放入对象中pageResult.setPageSize(pageRequest.getPageSize());// 将总条数放入对象中pageResult.setTotal(total);// 返回结果return pageResult;}/*** 获取* @return pageNum*/public int getPageNum() {return pageNum;}/*** 设置* @param pageNum*/public void setPageNum(int pageNum) {this.pageNum = pageNum;}/*** 获取* @return pageSize*/public int getPageSize() {return pageSize;}/*** 设置* @param pageSize*/public void setPageSize(int pageSize) {this.pageSize = pageSize;}/*** 获取* @return total*/public Long getTotal() {return total;}/*** 设置* @param total*/public void setTotal(Long total) {this.total = total;}/*** 获取* @return pages*/public int getPages() {return pages;}/*** 设置* @param pages*/public void setPages(int pages) {this.pages = pages;}/*** 获取* @return content*/public List<?> getContent() {return content;}/*** 设置* @param content*/public void setContent(List<?> content) {this.content = content;}public String toString() {return "PageResult{pageNum = " + pageNum + ", pageSize = " + pageSize + ", total = " + total + ", pages = " + pages + ", content = " + content + "}";}
}

三个实体类写完了后，接下来就是mapper层的编写

@Mapper
public interface StudentDao extends BaseMapper<Student> {List<Student> selectAllChd(PageRequest pageRequest);}

service的编写与实现类的编写

public interface StudentService  extends IService<Student> {List<Student> selectAllChd(PageRequest pageRequest);}

@Service
public class StudentServiceImpl extends ServiceImpl<StudentDao, Student> implements StudentService  {@ResourceStudentDao studentDao;@Overridepublic List<Student> selectAllChd(PageRequest pageRequest) {return studentDao.selectAllChd(pageRequest);}
}

再接着是controller的编写

@GetMapping("/query")
@ResponseBody
public PageResult queryList() {//分页写出来了System.out.println("进来了query");PageRequest pageRequest=new PageRequest(1,3);int pageNum = pageRequest.getPageNum();pageRequest.setPageNum((pageRequest.getPageSize()*(pageRequest.getPageNum()-1)));List<Student> carManagerEntityList =studentService.selectAllChd(pageRequest);pageRequest.setPageNum(pageNum);Long total = studentService.count();return PageResult.getPageResult(carManagerEntityList,pageRequest,total);
}

mybatis-plus虽然使用起来方便，但是俩表映射就不能使用自带的分页了，所以需要小伙伴自己手动写，下面是映射语句

<resultMap type="com.cskt.entity.Student" id="StudentMap"><result property="sId" column="s_id" jdbcType="INTEGER"/><result property="sName" column="s_name" jdbcType="VARCHAR"/><result property="sSex" column="s_sex" jdbcType="VARCHAR"/><association property="sClass" resultMap="ClassMap"></association>
</resultMap><resultMap id="ClassMap" type="com.cskt.entity.StuClass"><id property="cId" column="c_id"></id><result property="cName" column="c_name"></result>
</resultMap><select id="selectAllChd" resultMap="StudentMap">SELECT * FROM `student` as stu  join stu_class    as sts  on  stu.s_class=sts.c_id   limit #{pageNum} ,#{pageSize}
</select>

项目结构如下