[大数据]com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

### Error querying database.  
    Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 281 milliseconds ago.  The last packet sent successfully to the server was 266 milliseconds ago.
### The error may exist in com/wang/dao/UserMapper.xml
### The error may involve com.wang.dao.UserDao.getUserList
### The error occurred while executing a query
### Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

数据库配置如下：

<environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

maven配置：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.46</version>
</dependency>

两种原因导致这个问题

• mysql版本和驱动版本不匹配

讲mysql驱动配置改为

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.11</version>
</dependency>

同时修改数据库配置：

<property name="driver" value="com.mysql.cj.jdbc.Driver"/>

我的mysql版本为8.0.25修改后还是报错

• SSL=true

不建议在没有服务器身份验证的情况下建立SSL连接。根据MySQL 5.5.45+、5.6.26+和5.7.6+的要求，如果不设置显式选项，则必须建立默认的SSL连接。您需要通过设置useSSL=false显式地禁用SSL，或者设置useSSL=true并为服务器证书验证提供信任存储

这边将修改useSSL=false 不再报错