先贴一下错误

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:422)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:389)

at com.mysql.jdbc.Util.getInstance(Util.java:372)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:958)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:937)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:872)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2316)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2069)

at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:794)

at com.mysql.jdbc.JDBC4Connection.(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:422)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:389)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)

at java.sql.DriverManager.getConnection(DriverManager.java:664)

at java.sql.DriverManager.getConnection(DriverManager.java:270)

at com.personal.integral.test.JdbcClass.main(JdbcClass.java:16)

Caused by: java.lang.NullPointerException

at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2989)

at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1873)

at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1802)

at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1206)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2239)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2270)

... 13 more

控制台一直输出

Sun Oct 14 00:45:30 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended.

According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set.

For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'.

You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

主要原因就是mysql版本太高，版本不匹配导致的。

只需要修改 mysql-connector-java 版本

mysql

mysql-connector-java

5.1.37

改为8.0.11版本即可

mysql

mysql-connector-java

8.0.11

问题完美解决。