1 pom.xml 配置

<?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>3.2.3</version><relativePath/></parent><groupId>org.wl.study</groupId><artifactId>lockDemo</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-logging</artifactId></dependency><!-- https://mvnrepository.com/artifact/org.projectlombok/lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.30</version><scope>provided</scope></dependency><!--Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled.2023-11-27T11:21:35.750+08:00 ERROR 38028  [livestreaming_commerce] [main] o.s.boot.SpringApplication: Application run failedjava.lang.IllegalArgumentException: Invalid value type for attribute 'factoryBeanObjectType': java.lang.String主要是由于 mybatis-plus 中 mybatis 的整合包版本不够导致的排除 mybatis-plus 中自带的 mybatis 整合包单独引入即可--><!-- https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-boot-starter --><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.5</version><!-- 排除 com.baomidou自带的  mybatis-spring --><exclusions><exclusion><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId></exclusion></exclusions></dependency><!-- 重新依赖  mybatis-spring --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>3.0.3</version></dependency><!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.33</version></dependency><!-- https://mvnrepository.com/artifact/com.alibaba/fastjson --><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>2.0.47</version></dependency></dependencies><!-- maven 打包运行插件 --><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build>
</project>

2 application.properties

server.port=10010
logging.config=classpath:logback.xml
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://192.168.187.128:3306/DestributeLock?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&useSSL=false
spring.datasource.username=root
spring.datasource.password=Admin2024!#
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
#驼峰规则开启  java 对象 productCode 数据库 product_code
mybatis-plus.configuration.map-underscore-to-camel-case=true

3 启动类以及mapper 扫面配置

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
@MapperScan("org.wl.study.mapper")  //扫描mapper 接口public class LockDemoApplication {public static void main(String[] args) {SpringApplication.run(LockDemoApplication.class, args);}
}

4 controller 编写

@RestController
public class StockController
{public static final Logger logger = LoggerFactory.getLogger(StockController.class);@Autowiredprivate StockService stockService;@GetMapping("stock/reduce")public void reduce(){stockService.reduce();logger.info("库存减了");}
}

5 pojo / service / mapper 接口编写

package org.wl.study.pojo;import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
@TableName("stock")
@Data
public class Stock {//private Integer stockNumber = 5000;private Long id;private String productCode;private String wareHouse;private Integer count;
}@Resourceprivate StockMapper stockMapper;public void reduce() {System.out.println("=====================");Stock stock = stockMapper.selectOne(new QueryWrapper<Stock>().eq("product_code","1001"));if(stock != null && stock.getCount() > 0){stock.setCount(stock.getCount() -1);stockMapper.updateById(stock);logger.info("库存剩余:{}", stock.getCount());}}import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.wl.study.pojo.Stock;public interface StockMapper extends BaseMapper<Stock> {}测试结果
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79a6caba] was not registered for synchronization because synchronization is not active
JDBC Connection [HikariProxyConnection@449622079 wrapping com.mysql.cj.jdbc.ConnectionImpl@14051f75] will not be managed by Spring
==>  Preparing: UPDATE stock SET product_code=?, ware_house=?, count=? WHERE id=?
==> Parameters: 1001(String), BJ(String), 3993(Integer), 1(Long)
<==    Updates: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79a6caba]
23:35:30 [http-nio-10010-exec-4] INFO  o.w.s.c.service.StockService - 库存剩余:3993
23:35:30 [http-nio-10010-exec-4] INFO  o.w.study.controller.StockController - 库存减了