com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException问题解决

引言

台式机安装的 mysql 是8.0版本，今天重新下载了 jeecg3.7，导入数据库文件，项目启动时报如下错误。

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
    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:404)
    at com.mysql.jdbc.Util.getInstance(Util.java:387)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:898)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:887)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:862)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2331)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2084)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
    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:404)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)
    at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:142)
    at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:211)
    at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:136)
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1271)
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1325)
    at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:1215)
Caused by: java.lang.NullPointerException

解决步骤

方法就是，将驱动版本修改为与连接的数据库版本保持一致。

1、修改数据库连接信息，添加时区信息

 

 然鹅，并没起效。

2、修改mysql驱动版本，数据库版本和驱动版本保持一致

执行的sql文件中 mysql 版本是5.0，数据库版本是8.0，修改 pom 文件中 mysql 驱动版本，5.0 修改为 8.0。

 ok了。