找了半天
终于发现是generator坐标下没导mysql包
就是下面用横线隔开的地方

<build>
    <finalName>mmall</finalName>
    <plugins>
      <plugin>
        <groupId>org.mybatis.generator</groupId>
        <artifactId>mybatis-generator-maven-plugin</artifactId>
        <version>1.3.2</version>
-------------------------------------------------------------
        <dependencies>
          <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.12</version>
          </dependency>
        </dependencies>
----------------------------------------------------------
        <configuration>
          <verbose>true</verbose>
          <overwrite>true</overwrite>
        </configuration>
      </plugin>

      <!-- geelynote maven的核心插件之-complier插件默认只支持编译Java 1.4，因此需要加上支持高版本jre的配置，在pom.xml里面加上 增加编译插件 -->
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
          <encoding>UTF-8</encoding>
          <compilerArguments>
            <extdirs>${project.basedir}/src/main/webapp/WEB-INF/lib</extdirs>
          </compilerArguments>
        </configuration>
      </plugin>
    </plugins>

  </build>

还有就是jdbc的时区问题

db.driverLocation=D:/MySql/mysql-8.0.16-winx64/bin
db.driverClassName=com.mysql.cj.jdbc.Driver

db.url=jdbc:mysql://localhost:3306/mmall_learning?characterEncoding=utf-8&useSSL=false&serverTimezone=UTC
#db.url=jdbc:mysql://你的数据库IP:你的数据库Port/你的database?characterEncoding=utf-8
db.username=root
db.password=lhh123321