###### 问题遇到的现象和发生背景
导入项目链接不了数据库
###### 用代码块功能插入代码，请勿粘贴截图
java.sql.SQLException: Unknown character set index for field '255' received from server.
###### 运行结果及报错内容
创建数据库连接失败！
java.sql.SQLException: Unknown character set index for field '255' received from server.
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:910)
at com.mysql.jdbc.Connection.getCharsetNameForIndex(Connection.java:3448)
at com.mysql.jdbc.Field.(Field.java:191)
at com.mysql.jdbc.MysqlIO.unpackField(MysqlIO.java:659)
at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:382)
at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:1970)
at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:1387)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1727)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3170)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3099)
at com.mysql.jdbc.Statement.executeQuery(Statement.java:1169)
at com.mysql.jdbc.Connection.loadServerVariables(Connection.java:4317)
at com.mysql.jdbc.Connection.initializePropsFromServer(Connection.java:3936)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2683)
at com.mysql.jdbc.Connection.(Connection.java:1531)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at com.dao.DB.getCon(DB.java:52)
at com.dao.DB.doPstm(DB.java:69)
at com.service.loginService.login(loginService.java:49)
严重: dwr-invoker: Method execution failed:
java.lang.NullPointerException
at com.dao.DB.getRs(DB.java:94)
at com.service.loginService.login(loginService.java:52)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.directwebremoting.impl.ExecuteAjaxFilter.doFilter(ExecuteAjaxFilter.java:34)
at org.directwebremoting.impl.DefaultRemoter$1.doFilter(DefaultRemoter.java:428)
at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:431)
###### 我的解答思路和尝试过的方法
###### 我想要达到的结果
Mysql版本过高，而用的Mysql驱动版本过低造成的，你检查一下！！！