MySQL8-[问题解决]java.sql.SQLNonTransientConnectionException: Cannot load connection class because of underlying

对应为MySQL8和 MySQL-connecter8.0.16

1、修改MySQL驱动器

原来的版本：

com.mysql.jdbc.Driver

现在改为：
com.mysql.cj.jdbc.Driver

否则会告警：Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

2、修改连接MySQL的URL

原来的低版本是：

jdbc:mysql://localhost:3306/db_career?autoReconnect=true&useSSL=false&characterEncoding=utf-8

现在改为：

jdbc:mysql://localhost:3306/db_career?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT

否则报错：

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at RdsConcurrencyTest.getConn(RdsConcurrencyTest.java:21)
at RdsConcurrencyTest.main(RdsConcurrencyTest.java:57)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the 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.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:361)
at com.mysql.cj.protocol.a.NativeAuthenticationProvider.negotiateSSLConnection(NativeAuthenticationProvider.java:777)
at com.mysql.cj.protocol.a.NativeAuthenticationProvider.proceedHandshakeWithPluggableAuthentication(NativeAuthenticationProvider.java:486)
at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:202)
at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1452)
at com.mysql.cj.NativeSession.connect(NativeSession.java:165)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:955)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825)
... 7 more
Caused by: javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate)
at sun.security.ssl.HandshakeContext.<init>(HandshakeContext.java:171)
at sun.security.ssl.ClientHandshakeContext.<init>(ClientHandshakeContext.java:101)
at sun.security.ssl.TransportContext.kickstart(TransportContext.java:238)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:394)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:373)
at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:316)
at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:188)
at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:99)
at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:352)
... 14 more
Exception in thread "main" java.lang.NullPointerException
at RdsConcurrencyTest.main(RdsConcurrencyTest.java:61)