mybatisplus入门

搭建

mybatisplus部分依赖

  <!-- MyBatisPlus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>

pom.xml全部内容 

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
 
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.8</version>
        <relativePath/>
    </parent>
 
    <groupId>jkw.life</groupId>
    <artifactId>mybatis-plus-demo1</artifactId>
    <version>0.0.1</version>
 
 
    <dependencies>
        <!-- MyBatisPlus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
 
 
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--springMVC-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--springBoot起步依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
 
 
 
</project>

创建数据库

 DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `userId` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`userId`)
) ENGINE=InnoDB DEFAULT

 application.yml

server:
  port: 8080
 
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/atest?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    username: root
    password: root
 
 
#配置mybatis-plus(使用代码生成器时不要配置)
mybatis-plus:
  global-config:
    db-config:
      # 设置实体类所对应的表的统一前缀
      # table-prefix: t_
      # 主键生成策略为自增(属性只用加上@TableId  即可)
      id-type: auto
  configuration:
    # 关闭列名自动驼峰命名规则映射(列名的_自动映射成驼峰)(本项目中实体类和数据库表的列名一致，
    map-underscore-to-camel-case: false
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #开启sql日志
 
 
# 日志格式
logging:
  pattern:
    console: '%d{HH:mm:ss.SSS} %clr(%-5level) ---  [%-15thread] %cyan(%-50logger{50}):%msg%n'

编写启动类

package jkw;
 
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
/**
 * 启动类
 */
@SpringBootApplication
@MapperScan("jkw.mapper")
public class Main {
    public static void main(String[] args) {
        SpringApplication.run(Main.class, args);
    }
}

编写实体类

package jkw.pojo;
 
import com.baomidou.mybatisplus.annotation.TableId;
import lombok.Data;
 
/**
 * 用户实体类
 */
@Data
public class User {
    @TableId
    private Integer userId;
    private String username;//用户名
    private String password;//密码
}

简单的CRUD

mapper接口层

package jkw.mapper;
 
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import jkw.pojo.User;
 
public interface UserMapper extends BaseMapper {
}

service-增删改查

package jkw.service;
 
import jkw.mapper.UserMapper;
import jkw.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;
 
    /**
     * 新增用户
     *
     * @param user
     */
    public void add(User user) {
        userMapper.insert(user);
    }
 
    /**
     * 修改用户
     *
     * @param user
     */
    public void update(User user) {
        userMapper.updateById(user);
    }
 
    /**
     * 删除用户
     *
     * @param id
     */
    public void delete(Integer id) {
        userMapper.deleteById(id);
    }
 
    /**
     * 查询用户
     *
     * @param id
     * @return
     */
    public User findById(Integer id) {
        return userMapper.selectById(id);
    }
}