[Code Memo] How to output SQL logs to the console in MybatisPlus?

Mybatis Plus YYDS！

Thanks to my colleague Dr. L for pointing me in this content!

Ancestral chatter

When we use MybatisPlus for development, log output is very important for debugging and performance monitoring. MybatisPlus uses Log4j for log output by default, but if our project does not use Log4j, we can configure it log-impl: org.apache.ibatis.logging.stdout.StdOutImplto output the log to the console.

Code that can be copied after modification

First, add the following configuration in application.ymlor :application.properties

mybatis-plus:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath*:mapper/**/*.xml
  type-aliases-package: com.example.entity
  global-config:
    db-config:
      id-type: auto
    banner: false
    sql-parser-cache: false
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
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Among them, log-implthe implementation class of the log output is specified org.apache.ibatis.logging.stdout.StdOutImpl, that is, the console output. When the log is output, we can see the following output information:

2023-04-12 23:03:27.720  INFO 1126 --- [nio-8019-exec-1] c.b.p.controller.HeroController          : ==>  Preparing: SELECT * FROM hero WHERE id = ? 
2023-04-12 23:03:27.721  INFO 1126 --- [nio-8019-exec-1] c.b.p.controller.HeroController          : ==> Parameters: 1(Integer)
2023-04-12 23:03:27.724  INFO 1126 --- [nio-8019-exec-1] c.b.p.controller.HeroController          : <==      Total: 1
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As you can see, MybatisPlus outputs both SQL statements and parameters to the console.

The following is a complete Controller sample code for reference:

@RestController
@RequestMapping("/hero")
public class HeroController {

  @Autowired
  private HeroService heroService;

  @GetMapping("/{id}")
  public Hero getById(@PathVariable Integer id) {
    return heroService.getById(id);
  }
}
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Among them, the method of MybatisPlus is called in HeroService getById:

@Service
public class HeroServiceImpl extends ServiceImpl<HeroMapper, Hero> implements HeroService {

  @Override
  public Hero getById(Serializable id) {
    log.info("getById - id = {}", id);
    return super.getById(id);
  }
}
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In getByIdthe method, we added custom log output information for future debugging. At the same time, we configured log-implthe console output so that we can easily view the SQL log on the console.

references

- MybatisPlus官方文档：https://baomidou.com
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