org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

　　学习Mybatis的过程中，运行遇到这个问题。原因是在mybatis-config.xml文件配置中

<environments default="development">
    <environment id="development">
        <transactionManager type="JDBC"/>
        <dataSource type="POOLED">
            <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=GMT%2B8"/>
            <property name="username" value="root"/>
            <property name="password" value="******"/>
        </dataSource>
    </environment>
</environments>

在这一行

<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=GMT%2B8"/>

把useSSL=true改成useSSL=false就可以