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前言
我们在开发中经常需要操作数据库，传统的mybatis需要编写mapper和xml文件，工作量比较大，可以集成mybatisplus减少代码量，提高开发效率
MybatisPlus介绍
简介 | MyBatis-Plus
MyBatis-Plus 是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。
添加表及数据
DROP TABLE IF EXISTS `user`;CREATE TABLE `user`
(id BIGINT NOT NULL COMMENT '主键ID',name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',age INT NULL DEFAULT NULL COMMENT '年龄',email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',PRIMARY KEY (id)
);DELETE FROM `user`;INSERT INTO `user` (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');创建工程添加依赖
创建一个空的 Spring Boot 工程，引入 MyBatis-Plus Starter 依赖
添加了mybatisPlus的依赖就不需要添加mybatis的了，以免冲突
Spring Boot2
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.11</version>
</dependency>Spring Boot3
<dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId><version>3.5.11</version>
</dependency> <!-- 数据库驱动（以 MySQL 为例） --><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency>
配置
spring:application:name: joinDemodatasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/sbdemousername: rootpassword: 123456hikari:maximum-pool-size: 10connection-timeout: 30000mybatis-plus:configuration:log-impl: org.apache.ibatis.logging.stdout.StdOutImpl在 Spring Boot 启动类中添加 @MapperScan 注解，扫描 Mapper 文件夹：
@SpringBootApplication
@MapperScan("com.sky.joindemo.mapper")
public class JoinDemoApplication {public static void main(String[] args) {SpringApplication.run(JoinDemoApplication.class, args);}}
类
@Getter
@Setter
@ToString
@Accessors(chain = true)
public class User implements Serializable {private static final long serialVersionUID = 1L;/*** 主键ID*/@TableId(type = IdType.AUTO)private Long id;/*** 姓名*/private String name;/*** 年龄*/private Integer age;/*** 邮箱*/private String email;
}/*** <p>* Mapper 接口* </p>** @author sky* @since 2025-03-25*/
public interface UserMapper extends BaseMapper<User> {}单元测试
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.sky.joindemo.entity.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;import java.util.List;@SpringBootTest
class UserMapperTest {@Autowiredprivate UserMapper userMapper;@Testpublic void testSelect() {System.out.println(("----- selectAll method test ------"));List<User> userList = userMapper.selectList(null);Assert.isTrue(5 == userList.size(), "");userList.forEach(System.out::println);}@Testpublic void testSelectByWrapper() {//实体类上添加这个注解，可以链式访问@Accessors(chain = true)User user = new User().setName("Jack").setAge(18);QueryWrapper<User> queryWrapper = new QueryWrapper<>();queryWrapper.like(!StringUtils.isEmpty(user.getName()), "name", user.getName()).eq(user.getAge() != null, "age", user.getAge());List<User> userList = userMapper.selectList(queryWrapper);userList.forEach(System.out::println);}@Testpublic void testSelectByLambdaQueryWrapper() {User user = new User().setName("Jack").setAge(18);LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();lambdaQueryWrapper.like(!StringUtils.isEmpty(user.getName()),User::getName, "Jack").eq(user.getAge() != null,User::getAge, 18);List<User> userList = userMapper.selectList(lambdaQueryWrapper);userList.forEach(System.out::println);}
}代码生成器
使用代码生成器的话要引入
<!-- 模板引擎 --><dependency><groupId>org.apache.velocity</groupId><artifactId>velocity-engine-core</artifactId><version>2.3</version></dependency>
import com.baomidou.mybatisplus.generator.FastAutoGenerator;
import com.baomidou.mybatisplus.generator.engine.VelocityTemplateEngine;import java.nio.file.Paths;
import java.util.Scanner;public class CodeGenerator {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);System.out.println("请输入要生成代码的表名，多个表名用逗号分隔：");String tableNamesInput = scanner.nextLine();String[] tableNames = tableNamesInput.split(",");FastAutoGenerator.create("jdbc:mysql://localhost:3306/sbdemo", "root", "123456").globalConfig(builder -> builder.author("sky")// 开启 swagger 模式.outputDir(Paths.get(System.getProperty("user.dir")) + "/src/main/java").commentDate("yyyy-MM-dd")).packageConfig(builder -> builder.parent("com.sky.joindemo").entity("entity").mapper("mapper").service("service").serviceImpl("service.impl").xml("mapper.xml")).strategyConfig(builder -> builder.addInclude(tableNames).entityBuilder().enableLombok()).templateEngine(new VelocityTemplateEngine()).execute();}
}总结
mybatisPlus集成了很多现成的方法，可以快速的实现单表的增删改查。
生成的代码未必满足业务的需求，可以根据自己的需求微调一下，比如user类添加了@Accessors(chain = true)注解，可以实现链式赋值，主键也手工增加了@TableId(type = IdType.AUTO)注解