步骤：
1.坐标
<dependency>
<groupId>com.baimidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactld>
<version>3.4.3</version>
</dependency>
注意：mp坐标添加后，mybatis坐标移除
2.编写注解配置实体类与关系表映射关系（truncate清楚表以及主键）
@TableName(value="关系表名称")=======================》修在类
@TableField(value="关联字段名称"）=====================》修饰在属性
exist="忽略字段"
@TableId(type="指定主键生成策略，默认雪花算法”)==========》修饰在属性
AUTO(0),
NONE(1),
INPUT(2),
ASSIGN_ID(3),
ASSIGN_UUID(4);
3.使用
BaseMapper=======================================>公共的数据访问层
IService/ServiceImp=================================>公共的业务层
4.编写配置文件.YML
以下为具体实例
package com.ly.springboot_mybatis_01.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.ly.springboot_mybatis_01.pojo.Student;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;import java.util.List;@Mapper
public interface StudentMapper extends BaseMapper<Student> {@Select("select * from student")public List<Student> findall();
}
package com.ly.springboot_mybatis_01.config;import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class MyBatisPlusConfig {//注入mp拦截器@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor(){//实例化拦截器MybatisPlusInterceptor mybatisPlusInterceptor=new MybatisPlusInterceptor();mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());return mybatisPlusInterceptor;}
}
package com.ly.springboot_mybatis_01.pojo;import com.baomidou.mybatisplus.annotation.*;
import org.springframework.web.multipart.MultipartFile;//mybatisplus的注解可以省略，也已写上，但特殊的属性必须要写
@TableName(value = "student")
public class Student {@TableId(value = "stu_id",type = IdType.AUTO)private int stuId;@TableField(value = "stu_name")private String stuName;@TableField(value = "nick_name")private String nickName;@TableField(value = "stu_age")private int stuAge;//mybatis逻辑状态（0 表示未删，1 表示已删）@TableLogic(value = "0",delval = "1")private int isDelete;//数据库不存在该字段 用exist=false@TableField(exist = false)private MultipartFile file;public Student(String stuName, String nickName, int stuAge) {this.stuName = stuName;this.nickName = nickName;this.stuAge = stuAge;}@Overridepublic String toString() {return "Student{" +"stuId=" + stuId +", stuName='" + stuName + '\'' +", nickName='" + nickName + '\'' +", stuAge=" + stuAge +'}';}public int getStuId() {return stuId;}public void setStuId(int stuId) {this.stuId = stuId;}public String getStuName() {return stuName;}public void setStuName(String stuName) {this.stuName = stuName;}public String getNickName() {return nickName;}public void setNickName(String nickName) {this.nickName = nickName;}public int getStuAge() {return stuAge;}public void setStuAge(int stuAge) {this.stuAge = stuAge;}public Student() {}public Student(int stuId, String stuName, String nickName, int stuAge) {this.stuId = stuId;this.stuName = stuName;this.nickName = nickName;this.stuAge = stuAge;}
}
package com.ly.springboot_mybatis_01;import com.ly.springboot_mybatis_01.mapper.StudentMapper;
import com.ly.springboot_mybatis_01.pojo.Student;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;import java.util.List;@SpringBootApplication
//@MapperScan(basePackages = "com.ly.springboot_mybatis_01.mapper")
public class SpringbootMybatis01Application {public static void main(String[] args) {SpringApplication.run(SpringbootMybatis01Application.class, args);}}
测试二
package com.ly.springboot_mybatis_01;import com.ly.springboot_mybatis_01.mapper.StudentMapper;
import com.ly.springboot_mybatis_01.pojo.Student;
import org.junit.jupiter.api.Test;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.util.List;@SpringBootTestclass SpringbootMybatis01ApplicationTests {@Autowired(required = false)StudentMapper studentMapper;@Testvoid contextLoads() {List<Student> findall = studentMapper.findall();for (Student student : findall) {System.out.println(student);}}}
测试三
package com.ly.springboot_mybatis_01;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.ly.springboot_mybatis_01.mapper.StudentMapper;
import com.ly.springboot_mybatis_01.pojo.Student;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.util.Arrays;
import java.util.List;/*** @author 李妍* @Version 1.0* @since 2024/9/20*/
@SpringBootTest
public class Test1 {@Autowired(required = false)StudentMapper mapper;@Testpublic void show1(){Student student=new Student("依依","不晚",18);int i = mapper.insert(student);System.out.println("主键回填："+student.getStuId());System.out.println(i);}//修改ID@Testpublic void show2(){Student student=new Student();student.setStuId(5);student.setStuName("小郭");student.setNickName("玊尔");student.setStuAge(18);int i = mapper.updateById(student);System.out.println(i);}//修改name@Testpublic void show3(){//1.修改数据Student student=new Student();student.setNickName("晚风");student.setStuAge(20);//2.创建条件QueryWrapper<Student> wrapper=new QueryWrapper<Student>();wrapper.eq("stu_name","依依");mapper.update(student,wrapper);}//查询id@Testpublic void show4(){Student student=mapper.selectById(5);System.out.println(student);}//查询IDS@Testpublic void show5() {List<Student> students = mapper.selectBatchIds(Arrays.asList(1, 2, 5));for (Student student : students) {System.out.println(student);}}//聚合函数查询（null 表示全查）@Testpublic void show6(){QueryWrapper<Student> wrapper=new QueryWrapper<Student>();wrapper.eq("stu_age",18);Integer integer = mapper.selectCount(wrapper);System.out.println("年龄为18的个数："+integer+"个");}
//全查@Testpublic void show7(){QueryWrapper<Student> wrapper=new QueryWrapper<Student>();List<Student> students = mapper.selectList(null);for (Student student : students) {System.out.println(student);}}/*** mp分页使用* 注意：* 1.page.setCurrent(2);当前页码从1开始* 2.分页需要配置插件* *///分页@Testpublic void show8(){//定义分页规则Page<Student> page=new Page<Student>();page.setSize(2);//每页记录数page.setCurrent(3);//当前页码//查询条件QueryWrapper<Student> queryWrapper=new QueryWrapper<Student>();queryWrapper.eq("stu_age",18);IPage<Student> ipage = mapper.selectPage(page, null);List<Student> list = ipage.getRecords();System.out.println("总记录数："+ipage.getTotal());System.out.println("总计页数："+ipage.getPages());for (Student student : list) {System.out.println(student);}}//查询delete//物理查询，逻辑查询@Testpublic void show9(){mapper.deleteById(6);}
}
测试四
package com.ly.springboot_mybatis_01;import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.ly.springboot_mybatis_01.mapper.StudentMapper;
import com.ly.springboot_mybatis_01.pojo.Student;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.util.List;@SpringBootTest
public class Test02 {@Autowired(required = false)StudentMapper studentMapper;@Testpublic void show1(){LambdaQueryWrapper<Student> studentLambdaQueryWrapper=new LambdaQueryWrapper<>();studentLambdaQueryWrapper.ge(Student::getStuAge,18);List<Student> students = studentMapper.selectList(studentLambdaQueryWrapper);for (Student student : students) {System.out.println(student);}}}
spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/kj03?serverTimezone=GMTusername: password:
mybatis:configuration:map-underscore-to-camel-case: true
mybatis-plus:configuration:log-impl: org.apache.ibatis.logging.stdout.StdOutImplmap-underscore-to-camel-case: true