报错信息:com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. at sun.reflect.GeneratedConstructorAccessor138.newInstance(Unknown Source) 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:404) at com.mysql.jdbc.Util.getInstance(Util.java:387) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2330) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) at sun.reflect.GeneratedConstructorAccessor134.newInstance(Unknown Source) 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:404) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328) at com.fr.third.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1461) at com.fr.third.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1525) at com.fr.third.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2153) Caused by: java.lang.NullPointerException at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2997) at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1936) at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1865) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1228) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284) ... 12 more