MySQL 各种问题解决方案（一）

一、Spring 集成 MyBatis 连接失败的问题

java.sql.SQLException: Access denied for user 'Administrator'@'192.168.139.1' (using password: YES)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
    at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2191)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2222)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2017)
    at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:779)
    at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:47)
    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:425)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1510)
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1575)
    at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2450)

Spring 配置文件中 ${username} 会优先取用系统用户名，将 username 改为 mysql.username 就好。

二、CentOS 7 下 MySQL 5.7.27 不支持中文的解决办法

# 编辑配置文件
vim /etc/my.cnf
# 在[mysqld]下加入
character-set-server=utf8

进入 MySQL，执行 show variables like 'character%;，查看 character_set_server 的值为 utf8，修改完成。