文章目录
- 0 简要说明Pagehelper
- 1 搭建环境
- 1.1 项目目录
- 1.2 项目搭建需要的依赖
- 1.3 配置分页插件拦截器
- 1.4 源代码
- 启动类
- 实体类
- 数据层
- xml映射文件
- 业务层
- 业务层实现类
- 控制层
- 接口配置swagger
- 请求体
- 2 可能出现的疑问或者问题
- 2.1 关于total属性疑问
- 2.2 分页不生效问题
- 3 案例说明
- 3.1 配置信息
- 3.2 请求体
- 3.3 控制层
- 3.5 业务层
- 4.6 业务层实现类
- 4 关键问题：查询和录入操作使用一个dto出现强制分页情况【待定，问题未能复现，请稍等】
解决 PageInfo 返回的 total 不正确
关于PageInfo的total属性得到的值等于当前页记录数
Pagehelper官网
Pagehelper使用入门
0 简要说明Pagehelper
1 搭建环境
1.1 项目目录
1.2 项目搭建需要的依赖
<!-- SpringBoot的依赖配置--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>2.5.10</version><type>pom</type><scope>import</scope></dependency><!--Mybatis Plus 核心依赖--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version></dependency><!--MySQL驱动包--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.28</version></dependency><!--Mybatis Plus 扩展依赖--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-extension</artifactId><version>3.5.1</version></dependency><!--pagehelper分页插件--><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.0</version></dependency>
1.3 配置分页插件拦截器
在properties或者yml配置拦截器信息，使其生效。
Spring Boot 引入 starter 后自动生效，对分页插件进行配置时，在 Spring Boot 对应的配置文件 application.[properties|yaml] 中配置
# DataSource Config
spring:datasource:username: rootpassword: rooturl: jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf8&autoReconnect=true&rewriteBatchedStatements=true&serverTimezone=UTC&useSSL=false&allowMultiQueries=truedriver-class-name: com.mysql.cj.jdbc.Drivermvc:pathmatch:matching-strategy: ANT_PATH_MATCHER#配置日志
mybatis-plus:configuration:log-impl: org.apache.ibatis.logging.stdout.StdOutImplmapper-locations: classpath:mapper/*.xmlserver:port: 8089pagehelper:reasonable: truesupport-methods-arguments: trueparams: countSqlhelperDialect: mysqlreasonable:分页合理化参数，默认值为false。当该参数设置为 true 时，pageNum<=0 时会查询第一页， pageNum>pages（超过总数时），会查询最后一页。默认false 时，直接根据参数进行查询。
supportMethodsArguments：支持通过 Mapper 接口参数来传递分页参数，默认值false，分页插件会从查询方法的参数值中，自动根据上面 params 配置的字段中取值，查找到合适的值时就会自动分页。 使用方法可以参考测试代码中的 com.github.pagehelper.test.basic 包下的 ArgumentsMapTest 和 ArgumentsObjTest。
helperDialect：分页插件会自动检测当前的数据库链接，自动选择合适的分页方式。
params：为了支持startPage(Object params)方法，增加了该参数来配置参数映射，用于从对象中根据属性名取值， 可以配置 pageNum,pageSize,count,pageSizeZero,reasonable，不配置映射的用默认值， 默认值为pageNum=pageNum;pageSize=pageSize;count=countSql;reasonable=reasonable;pageSizeZero=pageSizeZero。
更加详细的参数说明，可以参考官网说明
1.4 源代码
启动类
package com.geekmice.sbpagehelper;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;/*** @BelongsProject: spring-boot-scaffold* @BelongsPackage: PACKAGE_NAME* @Author: pingmingbo* @CreateTime: 2023-08-05 15:14* @Description: TODO* @Version: 1.0*/
@MapperScan(value = "com.geekmice.sbpagehelper.dao")
@SpringBootApplication
public class SbPageHelperApplication {public static void main(String[] args) {SpringApplication.run(SbPageHelperApplication.class, args);}
}
实体类
package com.geekmice.sbpagehelper.domain;import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;import java.io.Serializable;/*** (Teacher)实体类** @author pingmingbo* @since 2023-08-05 15:19:26*/
@TableName("teacher")
@Data
public class Teacher implements Serializable {private static final long serialVersionUID = -82982716139385175L;/*** 教师号*/@TableId@TableField(value = "teacher_no")private String teacherNo;/*** 教师名称*/@TableField(value = "teacher_name")private String teacherName;/*** 部门编号*/@TableField(value = "category_id")private Integer categoryId;}
数据层
package com.geekmice.sbpagehelper.dao;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.geekmice.sbpagehelper.domain.Teacher;
import org.apache.ibatis.annotations.Param;
import java.util.List;/*** (Teacher)表数据库访问层** @author pingmingbo* @since 2023-08-05 15:19:26*/
public interface TeacherDao extends BaseMapper<Teacher> {}
xml映射文件
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.geekmice.sbpagehelper.dao.TeacherDao"><resultMap type="com.geekmice.sbpagehelper.domain.Teacher" id="TeacherMap"><result property="teacherNo" column="teacher_no" jdbcType="VARCHAR"/><result property="teacherName" column="teacher_name" jdbcType="VARCHAR"/><result property="categoryId" column="category_id" jdbcType="INTEGER"/></resultMap></mapper>
业务层
package com.geekmice.sbpagehelper.service;import com.baomidou.mybatisplus.extension.service.IService;
import com.geekmice.sbpagehelper.domain.Teacher;
import com.geekmice.sbpagehelper.dto.QueryDTO;
import com.github.pagehelper.PageInfo;import java.util.List;/*** (Teacher)表服务接口** @author pingmingbo* @since 2023-08-05 15:19:26*/
public interface TeacherService extends IService<Teacher> {/*** @return 响应信息* @description 初次使用分页查询*/List<Teacher> queryPage();/*** @param pageSize 当前页数* @param pageNum 每页条数* @return 返回信息* @description 分页参数查询*/PageInfo<Teacher> queryPage(int pageNum, int pageSize);/*** @param queryDTO 请求体* @return 响应信息* @description 多参数分页查询*/PageInfo<Teacher> queryPage(QueryDTO queryDTO);
}
业务层实现类
package com.geekmice.sbpagehelper.service.impl;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.geekmice.sbpagehelper.dao.TeacherDao;
import com.geekmice.sbpagehelper.domain.Teacher;
import com.geekmice.sbpagehelper.dto.QueryDTO;
import com.geekmice.sbpagehelper.service.TeacherService;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.List;/*** (Teacher)表服务实现类** @author pingmingbo* @since 2023-08-05 15:19:26*/
@Service("teacherService")
@Slf4j
public class TeacherServiceImpl extends ServiceImpl<TeacherDao, Teacher> implements TeacherService {@Resourceprivate TeacherDao teacherDao;/*** @return 响应信息* @description 初次使用分页查询*/@Overridepublic List<Teacher> queryPage() {PageHelper.startPage(1, 10);List<Teacher> result = teacherDao.selectList(null);return result;}/*** @param pageSize 当前页数* @param pageNum 每页条数* @return 返回信息* @description 分页参数查询*/@Overridepublic PageInfo<Teacher> queryPage(int pageNum, int pageSize) {PageHelper.startPage(pageNum, pageSize);QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();teacherQueryWrapper.likeRight("teacher_name", "小");List<Teacher> teachers = teacherDao.selectList(teacherQueryWrapper);PageInfo<Teacher> teacherPageInfo = new PageInfo<>(teachers);return teacherPageInfo;}/*** @param queryDTO 请求体* @return 响应信息* @description 多参数分页查询*/@Overridepublic PageInfo<Teacher> queryPage(QueryDTO queryDTO) {int pageNum = queryDTO.getPageNum();int pageSize = queryDTO.getPageSize();PageHelper.startPage(pageNum,pageSize);QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();teacherQueryWrapper.eq("teacher_name", queryDTO.getTeacherName());List<Teacher> teacherList = teacherDao.selectList(teacherQueryWrapper);PageInfo<Teacher> result = new PageInfo<>(teacherList);return result;}
}
控制层
package com.geekmice.sbpagehelper.controller;import com.geekmice.common.utils.AjaxResult;
import com.geekmice.sbpagehelper.domain.Teacher;
import com.geekmice.sbpagehelper.dto.QueryDTO;
import com.geekmice.sbpagehelper.service.TeacherService;
import com.github.pagehelper.PageInfo;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.web.bind.annotation.*;import javax.annotation.Resource;
import java.util.List;/*** (Teacher)表控制层** @author pingmingbo* @since 2023-08-05 15:19:26*/
@RestController
@RequestMapping("teacher")
@Api(tags = "0.分页查询模块")
public class TeacherController {/*** 服务对象*/@Resourceprivate TeacherService teacherService;/*** 通过主键查询单条数据** @param id 主键* @return 单条数据*/@ApiOperation(value = "查询单条数据")@GetMapping("selectOne")public Teacher selectOne(String id) {return null;}/*** @return 响应信息* @description 初次使用分页查询*/@GetMapping(value = "queryPage")@ApiOperation(value = "分页查询")public List<Teacher> queryPage() {List<Teacher> result = teacherService.queryPage();return result;}/*** @param pageSize 当前页数* @param pageNum 每页条数* @return 返回信息* @description 分页参数查询*/@GetMapping(value = "queryPageHavingParams")@ApiOperation(value = "分页查询带有参数")public AjaxResult queryPageHavingParams(int pageSize, int pageNum) {PageInfo<Teacher> result = teacherService.queryPage(pageNum, pageSize);return AjaxResult.success(result);}/*** @param queryDTO 请求体* @return 响应信息* @description 多参数分页查询*/@GetMapping(value = "queryPageByDTO")@ApiOperation(value = "多参数分页查询")public AjaxResult queryPageByDTO(QueryDTO queryDTO) {PageInfo<Teacher> result = teacherService.queryPage(queryDTO);return AjaxResult.success(result);}}
接口配置swagger
package com.geekmice.sbpagehelper.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.Contact;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;/*** @BelongsProject: spring-boot-scaffold* @BelongsPackage: com.geekmice.sbhelloworld.com.geekmice.sbpagehelper.config* @Author: pingmingbo* @CreateTime: 2023-07-30 15:45* @Description: TODO* @Version: 1.0*/
@Configuration
public class Knife4jConfig {@Bean(value = "defaultApi2")public Docket customDocket() {return new Docket(DocumentationType.SWAGGER_2).apiInfo(apiInfo()).select().apis(RequestHandlerSelectors.basePackage("com.geekmice.sbpagehelper.controller")).build();}/*** 构建 api文档的详细信息函数* @return*/private ApiInfo apiInfo() {return new ApiInfoBuilder().title("现货交易").version("1.0.0").description("现货交易详情").contact(new Contact("geekmice","http://geekmice.cn","2437690868@qq.com")).build();}
}
请求体
package com.geekmice.sbpagehelper.dto;import com.github.pagehelper.PageInfo;
import lombok.Data;/*** @BelongsProject: spring-boot-scaffold* @BelongsPackage: com.geekmice.sbpagehelper.dto* @Author: pingmingbo* @CreateTime: 2023-08-05 16:00* @Description: TODO* @Version: 1.0*/
@Data
public class QueryDTO extends PageInfo {private String teacherName;
}
2 可能出现的疑问或者问题
2.1 关于total属性疑问
2.2 分页不生效问题
- 当我们调用pagehelper.startPage（）方法后下一条语句必须是你要调用的查询语句；
- 我们的PageInfo传入的结果集，必须是我们调用查询语句返回的结果集；
提前说明：入参是 pageNum:1 pageSize:2 userName:张 模糊查询
正常情况，没有分页是有以张开头有三条数据，有分页的情况下 张1，张2
第一种问题复现如下：
List userDomainList = userDao.selectList(userDomainQueryWrapper); // 位置1
PageHelper.startPage(pageNum, pageSize); // 位置2
int pageNum = userVO.getPageNum();int pageSize = userVO.getPageSize();String userName = userVO.getUserName();QueryWrapper<UserDomain> userDomainQueryWrapper = new QueryWrapper<>();userDomainQueryWrapper.likeRight("user_name", userName);List<UserDomain> userDomainList = userDao.selectList(userDomainQueryWrapper); // 位置1PageInfo<UserDomain> userDomainPageInfo = new PageInfo<>(userDomainList);PageHelper.startPage(pageNum, pageSize); // 位置2return userDomainPageInfo;
返回结果有疑问:返回的是没有分页，只要是张开头的数据都返回了。
{"msg": "操作成功","code": 200,"data": {"total": 3,"list": [{"id": 1,"userName": "张1","birthday": "2023-08-09T16:00:00.000+00:00","sex": "男","address": "123@163.com"},{"id": 3,"userName": "张2","birthday": "2023-08-09T16:00:00.000+00:00","sex": "女","address": "999@163.com"},{"id": 4,"userName": "张3","birthday": "2023-08-09T16:00:00.000+00:00","sex": "男","address": "9994@qq.com"}],"pageNum": 1,"pageSize": 4,"size": 3,"startRow": 1,"endRow": 3,"pages": 1,"prePage": 0,"nextPage": 0,"isFirstPage": true,"isLastPage": true,"hasPreviousPage": false,"hasNextPage": false,"navigatePages": 8,"navigatepageNums": [1],"navigateFirstPage": 1,"navigateLastPage": 1}
}
3 案例说明
3.1 配置信息
添加依赖
<dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.0</version></dependency>
yml配置信息
pagehelper:reasonable: truesupport-methods-arguments: trueparams: countSqlhelperDialect: mysql
3.2 请求体
PageInfo这个api是Pagehelper原生的对象，涵盖基本分页信息
package com.geekmice.sbpagehelper.dto;import com.github.pagehelper.PageInfo;
import lombok.Data;/*** @BelongsProject: spring-boot-scaffold* @BelongsPackage: com.geekmice.sbpagehelper.dto* @Author: pingmingbo* @CreateTime: 2023-08-05 16:00* @Description: TODO* @Version: 1.0*/
@Data
public class QueryDTO extends PageInfo {private String teacherName;
}
3.3 控制层
/*** (Teacher)表控制层** @author pingmingbo* @since 2023-08-05 15:19:26*/
@RestController
@RequestMapping("teacher")
@Api(tags = "0.分页查询模块")
public class TeacherController {/*** 服务对象*/@Resourceprivate TeacherService teacherService;/*** @param queryDTO 请求体* @return 响应信息* @description 多参数分页查询*/@GetMapping(value = "queryPageByDTO")@ApiOperation(value = "多参数分页查询")public AjaxResult queryPageByDTO(QueryDTO queryDTO) {PageInfo<Teacher> result = teacherService.queryPage(queryDTO);return AjaxResult.success(result);}
}
3.5 业务层
package com.geekmice.sbpagehelper.service;import com.baomidou.mybatisplus.extension.service.IService;
import com.geekmice.sbpagehelper.domain.Teacher;
import com.geekmice.sbpagehelper.dto.QueryDTO;
import com.github.pagehelper.PageInfo;import java.util.List;/*** (Teacher)表服务接口** @author pingmingbo* @since 2023-08-05 15:19:26*/
public interface TeacherService extends IService<Teacher> {/*** @param queryDTO 请求体* @return 响应信息* @description 多参数分页查询*/PageInfo<Teacher> queryPage(QueryDTO queryDTO);
}
4.6 业务层实现类
package com.geekmice.sbpagehelper.service.impl;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.geekmice.sbpagehelper.dao.TeacherDao;
import com.geekmice.sbpagehelper.domain.Teacher;
import com.geekmice.sbpagehelper.dto.QueryDTO;
import com.geekmice.sbpagehelper.service.TeacherService;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.stereotype.Service;import javax.annotation.Resource;
import java.util.List;
import java.util.stream.Collectors;/*** (Teacher)表服务实现类** @author pingmingbo* @since 2023-08-05 15:19:26*/
@Service("teacherService")
@Slf4j
public class TeacherServiceImpl extends ServiceImpl<TeacherDao, Teacher> implements TeacherService {@Resourceprivate TeacherDao teacherDao;/*** @param queryDTO 请求体* @return 响应信息* @description 多参数分页查询*/@Overridepublic PageInfo<Teacher> queryPage(QueryDTO queryDTO) {int pageNum = queryDTO.getPageNum();int pageSize = queryDTO.getPageSize();QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();teacherQueryWrapper.eq("teacher_name", queryDTO.getTeacherName());PageHelper.startPage(pageNum,pageSize);List<Teacher> teacherList = teacherDao.selectList(teacherQueryWrapper);PageInfo<Teacher> result = new PageInfo<>(teacherList );return result;}
}
再次说明 PageHelper.startPage(pageNum,pageSize);使用顺序
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