在SpringMVC+Spring+MyBatis整合利用中拜访Mysql呈现以下报错
具体报错：

19-Feb-2021 11:08:54.808 重大 [Druid-ConnectionPool-Create-1512829159] com.alibaba.druid.support.logging.JakartaCommonsLoggingImpl.error create connection SQLException, url: jdbc:mysql://localhost:3306/springdb, errorCode 0, state S1000    java.sql.SQLException: Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)        at com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1734)        at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3539)        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2151)        at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:776)        at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)        at java.lang.reflect.Constructor.newInstance(Constructor.java:423)        at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)        at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:352)        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:284)        at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1570)        at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1636)        at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2505)

查看，查问mysql的版本发现本地的是8.0.22，更改maven的pom.xml文件的mysql驱动版本为8.0.22，刷新pom.xml，重新启动利用即可

   <dependency>            <groupId>mysql</groupId>            <artifactId>mysql-connector-java</artifactId>            <version>8.0.22</version>        </dependency>

百度过程中还发现driverClassName有可能会报这个错，然而这里的不是这个起因

driverClassName: com.mysql.jdbc.Driver    # mysql-connector-java 5.x及之前版本中的driverClassName: com.mysql.cj.jdbc.Driver # mysql-connector-java 6.x及后续版本中的

这里有一个疑难？

  1. driverClassName没配置利用也能够失常拜访数据库，配置了也能够，这个是什么原理？

百度了临时没找到为什么

  1. characterEncoding=UTF-8 加不加都能够
    <!--申明数据源,连贯数据库-->    <context:property-placeholder location="classpath:conf/jdbc.properties"/>    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"          init-method="init" destroy-method="close"><!--        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>--><!--        <property name="url" value="${jdbc.url}?characterEncoding=UTF-8"/>-->        <property name="url" value="${jdbc.url}"/>        <property name="username" value="${jdbc.username}"/>        <property name="password" value="${jdbc.password}"/>    </bean>

问题1：driverClassName没配置利用也能够失常拜访数据库，配置了也能够，这个是什么原理？
有大佬指导可能是以下状况（未验证，先记录了前面有工夫在验证吧）

  1. 在mysql的驱动jar中曾经配置了

  1. 在com.alibaba.druid.pool.DruidDataSource配置的