5spring flowers 5、SpringBoot整合之SpringBoot整合MybatisPlus

SpringBoot整合MybatisPlus目录（可点击直接跳转，但还是建议按照顺序观看，四部分具有一定的关联性）：
实现基础的增删改查
实现自动填充功能
实现逻辑删除
实现分页
首先给出四部分完整的项目结构

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一、实现基础的增删改查功能1.创建项目、选择依赖【5spring flowers 5、SpringBoot整合之SpringBoot整合MybatisPlus】选择Spring Web、JDBC API、MyBatis Framework、MySQL Driver

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2.在pom文件中引入相关依赖

<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><!-- 修改jdbc版本 --><version>5.1.47</version><scope>runtime</scope></dependency><!-- 引入MybatisPlus的启动器 --><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.3.2</version></dependency><!-- 引入lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency><!-- 引入druid连接池 --><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.2.6</version></dependency><!-- 引入log4j --><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency>

3.建库、建表、插入数据

CREATE DATABASE db_mybatisplus;USE db_mybatisplus;CREATE TABLE tab_teacher(pk_teacher_id INT PRIMARY KEY AUTO_INCREMENT COMMENT '老师主键id,起始为1',teacher_name VARCHAR(10) COMMENT '老师姓名',teacher_sex CHAR(1) COMMENT '老师性别',teacher_salary DOUBLE(6,1) COMMENT '老师工资');-- 反复执行多次 ， 随机插入多条数据INSERT INTO tab_teacher VALUES(NULL,SUBSTR(MD5(RAND()), 1, 5),IF(RAND()>0.5, '男', '女'),RAND()*10000+1000);SELECT * FROM tab_teacher;

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4.配置核心配置文件

# 配置连接数据库的四大参数spring.datasource.driver-class-name=com.mysql.jdbc.Driverspring.datasource.url=jdbc:mysql://192.168.133.139/db_mybatisplus?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=truespring.datasource.username=rootspring.datasource.password=root# 指定连接池的类型spring.datasource.type=com.alibaba.druid.pool.DruidDataSource# 显示SQL语句mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

5.创建实体类

package cn.byuan.entity;import com.baomidou.mybatisplus.annotation.IdType;import com.baomidou.mybatisplus.annotation.TableField;import com.baomidou.mybatisplus.annotation.TableId;import com.baomidou.mybatisplus.annotation.TableName;import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;import lombok.experimental.Accessors;import java.io.Serializable;@NoArgsConstructor// 创建无参的构造方法@AllArgsConstructor// 创建满参的构造方法@Accessors(chain = true)// 使用链式方法@Data// 重写toString方法等方法@TableName("tab_teacher")// 对应表名public class Teacher implements Serializable {@TableId(value = "https://tazarkount.com/read/pk_teacher_id", type = IdType.AUTO)// 主键必须有TableId注解private Integer teacherId;@TableField("teacher_name")private String teacherName;@TableField("teacher_sex")private String teacherSex;@TableField("teacher_salary")private Double teacherSalary;}

6.创建Teacher类的dao接口，继承BaseMapper接口，使用BaseMapper接口的方法这里我省去了mapper层，直接让dao层接口继承BaseMapper
这里要牢记一个原则：在启动类对继承BaseMapper的类进行扫描，谁继承BaseMapper类就对它进行扫描

package cn.byuan.dao;import cn.byuan.entity.Teacher;import com.baomidou.mybatisplus.core.mapper.BaseMapper;import org.springframework.stereotype.Repository;@Repositorypublic interface TeacherDao extends BaseMapper<Teacher> {}

7.创建service接口及实现类接口：

import cn.byuan.entity.Teacher;import java.util.List;public interface TeacherService {//添加一位老师Integer addOneTeacher(Teacher teacher);//根据id删除一位老师Integer deleteOneTeacherByTeacherId(Integer teacherId);//修改一位老师的信息Integer updateOneTeacher(Teacher teacher);//根据id查询一位老师Teacher getOneTeacherByTeacherId(Integer teacherId);//获取所有老师List<Teacher> getAllTeacher();}

实现类：

package cn.byuan.service;import cn.byuan.dao.TeacherDao;import cn.byuan.entity.Teacher;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import java.util.List;@Servicepublic class TeacherServiceImp implements TeacherService{@Autowiredprivate TeacherDao teacherDao;//添加一位老师public Integer addOneTeacher(Teacher teacher){return teacherDao.insert(teacher);}//根据id删除一位老师public Integer deleteOneTeacherByTeacherId(Integer teacherId){return teacherDao.deleteById(teacherId);}//修改一位老师的信息public Integer updateOneTeacher(Teacher teacher){return teacherDao.updateById(teacher);}//根据id查询一位老师public Teacher getOneTeacherByTeacherId(Integer teacherId){return teacherDao.selectById(teacherId);}//获取所有老师public List<Teacher> getAllTeacher(){return teacherDao.selectList(null);}}

8.在启动类对继承BaseMapper的类配置扫描谁继承了BaseMapper就对谁进行扫描，因为之前我省去了mapper层，直接让dao层接口继承BaseMapper ，因此这里扫描的是dao包

package cn.byuan;import org.mybatis.spring.annotation.MapperScan;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication@MapperScan("cn.byuan.dao")// 那一层继承了BaseMapper就对那一层进行扫描public class Test005SpringbootMybatisplusApplication {public static void main(String[] args) {SpringApplication.run(Test005SpringbootMybatisplusApplication.class, args);}}

9.在测试类进行测试

package cn.byuan;import cn.byuan.entity.Teacher;import cn.byuan.service.TeacherService;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;@SpringBootTestclass TeacherDaoOneTests {@Autowiredprivate TeacherService teacherService;@Testvoid addOneTeacherTest(){Teacher teacher = new Teacher().setTeacherName("test2").setTeacherSex("女").setTeacherSalary(9876.5);teacherService.addOneTeacher(teacher);}@Testvoid deleteOneTeacherByTeacherIdTest(){teacherService.deleteOneTeacherByTeacherId(2);}@Testvoid updateOneTeacher(){Teacher teacher = new Teacher().setTeacherId(1).setTeacherName("qwe12").setTeacherSex("女").setTeacherSalary(1234.5);teacherService.updateOneTeacher(teacher);}@Testvoid getOneTeacherByTeacherId(){teacherService.getOneTeacherByTeacherId(1);}@Testvoid getAllTeacher(){teacherService.getAllTeacher();}}

测试结果：

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二、实现自动填充功能自动填充功能一般可以用作记录操作发生时间，如某列的最后修改时间等，本部分代码基于第一部分：实现基础的增删改查、
1.修改数据库中的表结构

-- 修改数据库中表结构ALTER TABLE tab_teacher ADD create_time TIMESTAMP COMMENT '记录插入时间';ALTER TABLE tab_teacher ADD update_time TIMESTAMP COMMENT '记录修改时间';-- 更新所有表中数据UPDATE tab_teacher SET create_time=NOW();UPDATE tab_teacher SET update_time=NOW();SELECT * FROM tab_teacher;

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2.修改实体类这一步简单来说就是将增加的两列添加进Teacher类的属性中，其余与第一部分保持一致；
为实现自动填充还应在新加入的两个属性的TableField中增加"fill"属性

package cn.byuan.entity;import com.baomidou.mybatisplus.annotation.IdType;import com.baomidou.mybatisplus.annotation.TableField;import com.baomidou.mybatisplus.annotation.TableId;import com.baomidou.mybatisplus.annotation.TableName;import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;import lombok.experimental.Accessors;import java.io.Serializable;import java.util.Date;@NoArgsConstructor// 创建无参的构造方法@AllArgsConstructor// 创建满参的构造方法@Accessors(chain = true)// 使用链式方法@Data// 重写toString方法等方法@TableName("tab_teacher")// 对应表名public class Teacher implements Serializable {@TableId(value = "https://tazarkount.com/read/pk_teacher_id", type = IdType.AUTO)// 主键必须有TableId注解private Integer teacherId;@TableField("teacher_name")private String teacherName;@TableField("teacher_sex")private String teacherSex;@TableField("teacher_salary")private Double teacherSalary;//增加的两列属性@TableField(value = "https://tazarkount.com/read/create_time", fill = FieldFill.INSERT)// 插入时自动填充private Date createTime;@TableField(value = "https://tazarkount.com/read/update_time", fill = FieldFill.INSERT_UPDATE)// 插入和修改时自动填充private Date updateTime;}

3.创建handler层，实现MetaObjectHandler接口，重写insertFill与updateFill方法，指定填充的字段及属性值

package cn.byuan.handler;import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;import org.apache.ibatis.reflection.MetaObject;import org.springframework.stereotype.Component;import java.util.Date;@Componentpublic class TeacherHandler implements MetaObjectHandler {@Overridepublic void insertFill(MetaObject metaObject) {this.strictInsertFill(metaObject, "createTime", Date.class, new Date());this.strictInsertFill(metaObject, "updateTime", Date.class, new Date());}@Overridepublic void updateFill(MetaObject metaObject) {this.strictUpdateFill(metaObject, "updateTime", Date.class, new Date());}}

4.进行测试这里我们只测试增加和修改两个方法

package cn.byuan;import cn.byuan.entity.Teacher;import cn.byuan.service.TeacherService;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;@SpringBootTestclass TeacherDaoTwoTests {@Autowiredprivate TeacherService teacherService;@Testvoid addOneTeacherTest(){Teacher teacher = new Teacher().setTeacherName("test2").setTeacherSex("女").setTeacherSalary(9876.5);teacherService.addOneTeacher(teacher);}@Testvoid updateOneTeacher(){Teacher teacher = new Teacher().setTeacherId(1).setTeacherName("wer23").setTeacherSex("女").setTeacherSalary(1234.5);teacherService.updateOneTeacher(teacher);}}

从SQL语句可以看出，在执行update方法时，已自动为我们填充字段

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数据库中新插入数据也没有问题

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三、实现逻辑删除功能数据是无价的，因此一般而言我们不会直接删除数据。对于"删除"我们一般的做法是定义一个字段来记录本行数据的可见性
1.修改数据库中的表结构添加一个字段作为标记

-- 修改数据库中表结构, 添加一个字段作为标记ALTER TABLE tab_teacher ADD visibility TINYINT COMMENT "0表示未删除 ， 1表示删除";-- 更新表中所有数据, 全部设置为未删除UPDATE tab_teacher SET visibility=0;

2.在实体类中添加字段，并添加TableField和TableLogic两个注解

package cn.byuan.entity;import com.baomidou.mybatisplus.annotation.*;import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;import lombok.experimental.Accessors;import java.io.Serializable;import java.util.Date;@NoArgsConstructor// 创建无参的构造方法@AllArgsConstructor// 创建满参的构造方法@Accessors(chain = true)// 使用链式方法@Data// 重写toString方法等方法@TableName("tab_teacher")// 对应表名public class Teacher implements Serializable {@TableId(value = "https://tazarkount.com/read/pk_teacher_id", type = IdType.AUTO)// 主键必须有TableId注解private Integer teacherId;@TableField("teacher_name")private String teacherName;@TableField("teacher_sex")private String teacherSex;@TableField("teacher_salary")private Double teacherSalary;@TableField(value = "https://tazarkount.com/read/create_time", fill = FieldFill.INSERT)// 插入时自动填充private Date createTime;@TableField(value = "https://tazarkount.com/read/update_time", fill = FieldFill.INSERT_UPDATE)// 插入和修改时自动填充private Date updateTime;//新添加进来的字段@TableField(value = "https://tazarkount.com/read/visibility", fill = FieldFill.INSERT)@TableLogic(value = "https://tazarkount.com/read/0", delval = "1")// 指定次字段为逻辑删除字段, 默认0是未删除, 1是已删除private Integer visibility;}

3.在TeacherHandler中指定visibility字段的初始值

package cn.byuan.handler;import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;import org.apache.ibatis.reflection.MetaObject;import org.springframework.stereotype.Component;import java.util.Date;@Componentpublic class TeacherHandler implements MetaObjectHandler {@Overridepublic void insertFill(MetaObject metaObject) {this.strictInsertFill(metaObject, "createTime", Date.class, new Date());this.strictInsertFill(metaObject, "updateTime", Date.class, new Date());//新添加的字段this.strictInsertFill(metaObject, "visibility", Integer.class, 0);}@Overridepublic void updateFill(MetaObject metaObject) {this.strictUpdateFill(metaObject, "updateTime", Date.class, new Date());}}

4.进行测试这里只测试两个方法，一个是删除指定id值的老师，一个是根据被删除的老师id查询该老师是否可以被查询

package cn.byuan;import cn.byuan.entity.Teacher;import cn.byuan.service.TeacherService;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;@SpringBootTestclass TeacherDaoThreeTests {@Autowiredprivate TeacherService teacherService;@Testvoid deleteOneTeacherByTeacherIdTest(){//删除id为1的老师teacherService.deleteOneTeacherByTeacherId(1);}@Testvoid getOneTeacherByTeacherId(){//查询id为1的老师teacherService.getOneTeacherByTeacherId(1);}}

可以看到，当我们执行delete方法时，实际上执行的是update方法
而查询语句并没有查询到该老师

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数据库中id为1的老师信息依然存在

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四、实现分页功能1.创建一个配置类，通过方法返回一个PaginationInterceptor

package cn.byuan.conf;import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;import org.mybatis.spring.annotation.MapperScan;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configuration@MapperScan("cn.byuan.dao")public class PageConfig {@Beanpublic PaginationInterceptor PaginationInterceptor(){return new PaginationInterceptor();}}

2.在service中根据selectPage方法进行分页这里展示两种分页方式，对表中所有数据进行分页以及根据条件进行分页
接口：

package cn.byuan.service;import cn.byuan.entity.Teacher;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import java.util.List;public interface TeacherService {//添加一位老师Integer addOneTeacher(Teacher teacher);//根据id删除一位老师Integer deleteOneTeacherByTeacherId(Integer teacherId);//修改一位老师的信息Integer updateOneTeacher(Teacher teacher);//根据id查询一位老师Teacher getOneTeacherByTeacherId(Integer teacherId);//获取所有老师List<Teacher> getAllTeacher();//该部分增加的方法//对表中所有信息进行分页, 传入参数为要查询的页数Page<Teacher> getAllTeacherPage(Integer pageNumber);//按条件(性别)进行分页Page<Teacher> getAllTeacherByTeacherSexPage(Integer pageNumber, String teacherSex);}

实现类：

package cn.byuan.service;import cn.byuan.dao.TeacherDao;import cn.byuan.entity.Teacher;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import java.util.List;@Servicepublic class TeacherServiceImp implements TeacherService{@Autowiredprivate TeacherDao teacherDao;//添加一位老师public Integer addOneTeacher(Teacher teacher){return teacherDao.insert(teacher);}//根据id删除一位老师public Integer deleteOneTeacherByTeacherId(Integer teacherId){return teacherDao.deleteById(teacherId);}//修改一位老师的信息public Integer updateOneTeacher(Teacher teacher){return teacherDao.updateById(teacher);}//根据id查询一位老师public Teacher getOneTeacherByTeacherId(Integer teacherId){return teacherDao.selectById(teacherId);}//获取所有老师public List<Teacher> getAllTeacher(){return teacherDao.selectList(null);}//该部分增加的方法//对表中所有信息进行分页, 传入参数为要查询的页数public Page<Teacher> getAllTeacherPage(Integer pageNumber){QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();Page<Teacher> teacherPage = new Page<>(pageNumber, 5);// 每页大小为5teacherDao.selectPage(teacherPage, teacherQueryWrapper);return teacherPage;}//按条件(性别)进行分页public Page<Teacher> getAllTeacherByTeacherSexPage(Integer pageNumber, String teacherSex){QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();teacherQueryWrapper.eq("teacher_sex", teacherSex);// 根据条件进行分页, 这里填写的是表中的列名Page<Teacher> teacherPage = new Page<>(pageNumber, 5);teacherDao.selectPage(teacherPage, teacherQueryWrapper);return teacherPage;}}

3.进行测试

package cn.byuan;import cn.byuan.entity.Teacher;import cn.byuan.service.TeacherService;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;@SpringBootTestclass TeacherDaoFourTests {@Autowiredprivate TeacherService teacherService;@Testvoid getAllTeacherPageTest(){//查看第三页Page<Teacher> teacherPage = teacherService.getAllTeacherPage(3);teacherPage.getRecords().forEach(System.out::println);}@Testvoid getAllTeacherByTeacherSexPageTest(){//查询男生第1页的内容Page<Teacher> teacherPage = teacherService.getAllTeacherByTeacherSexPage(1, "男");teacherPage.getRecords().forEach(System.out::println);}}

测试结果

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附：Page对象的一些常用方法

Page<Object> page = new Page<>(1, 6);// 指定当前页, 每页记录数page.getCurrent();// 获取当前页page.getTotal();// 获取总记录数page.getSize();// 获取每页的记录数page.getRecords();// 获取当前页数据的集合page.getPages();// 获取总页数page.hasNext();// 是否存在下一页page.hasPrevious();// 是否存在上一页

源码地址：https://github.com/byuan98/springboot-integration/tree/master/test005_springboot_mybatisplus