1、方法一

mybatis的添加配置文件----mybatis-config.xml如下

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <!-- 打印sql日志 -->
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>
</configuration>

springboot的配置文件----appcation.yml中添加

mybatis:
    configuration:
      log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

mybatis.configuration.log-impl= org.apache.ibatis.logging.stdout.StdOutImpl

2、方法二

springboot+mybatis整合中，可以将springboot的配置文件添加

logging:
  level:
    com.lucifer.springboot.cache.mapper: debug

com.lucifer.springboot.cache.mapper是包名

3、方法三

springboot+mybatis-plus

  <dependency>
       <groupId>com.baomidou</groupId>
       <artifactId>mybatis-plus-boot-starter</artifactId>
       <version>3.3.1</version>
  </dependency>

application.yml

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

JDBC Connection [HikariProxyConnection@1006460161 wrapping com.mysql.cj.jdbc.ConnectionImpl@37cccae8] will not be managed by Spring
==>  Preparing: SELECT id,user_name,age FROM user WHERE (user_name = ?) 
==> Parameters: 张三(String)
<==    Columns: id, user_name, age
<==        Row: 1, 张三, 18
<==      Total: 1