背景：两台电脑，一台装了虚拟机，准备做服务器用，另一台当客户端，同一局域网下两台电脑+一台虚拟机 联机，虚拟机上安装好、启动好 mysql 8.0.27，使用 Navicat、命令行均可连接成功，使用java 代码连接时，报：
2021-12-18 22:33:42.181 INFO 6358 --- [nio-9091-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet' 2021-12-18 22:33:42.181 INFO 6358 --- [nio-9091-exec-2] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet' 2021-12-18 22:33:42.183 INFO 6358 --- [nio-9091-exec-2] o.s.web.servlet.DispatcherServlet : Completed initialization in 2 ms 2021-12-18 22:33:42.255 INFO 6358 --- [nio-9091-exec-2] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting... 2021-12-18 22:33:43.605 ERROR 6358 --- [nio-9091-exec-2] com.zaxxer.hikari.pool.HikariPool : HikariPool-1 - Exception during pool initialization. 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) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:364) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:476) [HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:561) [HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-4.0.3.jar:na] at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:159) [spring-jdbc-5.3.13.jar:5.3.13] at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:117) [spring-jdbc-5.3.13.jar:5.3.13] at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80) [spring-jdbc-5.3.13.jar:5.3.13] at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82) [mybatis-spring-1.3.2.jar:1.3.2] at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68) [mybatis-spring-1.3.2.jar:1.3.2] at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:338) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77) [mybatis-3.4.6.jar:3.4.6] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_291] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_291] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_291] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_291] at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433) [mybatis-spring-1.3.2.jar:1.3.2] at com.sun.proxy.$Proxy58.selectOne(Unknown Source) [na:na] at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:166) [mybatis-spring-1.3.2.jar:1.3.2] at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:83) [mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59) [mybatis-3.4.6.jar:3.4.6] at com.sun.proxy.$Proxy66.selectByPrimaryKey(Unknown Source) [na:na] at com.example.service.impl.UserServiceImpl.selectById(UserServiceImpl.java:22) [classes/:na] at com.example.controller.UserController.selectById(UserController.java:24) [classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_291] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_291] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_291] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_291] at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) [spring-web-5.3.13.jar:5.3.13] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) [spring-web-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) [spring-webmvc-5.3.13.jar:5.3.13] at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) [tomcat-embed-core-9.0.55.jar:4.0.FR] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.3.13.jar:5.3.13] at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) [tomcat-embed-core-9.0.55.jar:4.0.FR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.3.13.jar:5.3.13] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.13.jar:5.3.13] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.3.13.jar:5.3.13] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.13.jar:5.3.13] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.3.13.jar:5.3.13] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.13.jar:5.3.13] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1722) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.55.jar:9.0.55] at java.lang.Thread.run(Thread.java:748) [na:1.8.0_291] 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) ~[na:1.8.0_291] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_291] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_291] at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_291] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:317) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:203) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1369) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818) ~[mysql-connector-java-8.0.27.jar:8.0.27] ... 87 common frames omitted Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateNotYetValidException: NotBefore: Sun Dec 19 02:30:18 CST 2021 at sun.security.ssl.Alert.createSSLException(Alert.java:131) ~[na:1.8.0_291] at sun.security.ssl.TransportContext.fatal(TransportContext.java:370) ~[na:1.8.0_291] at sun.security.ssl.TransportContext.fatal(TransportContext.java:313) ~[na:1.8.0_291] at sun.security.ssl.TransportContext.fatal(TransportContext.java:308) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:652) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.onCertificate(CertificateMessage.java:471) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.consume(CertificateMessage.java:367) ~[na:1.8.0_291] at sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:376) ~[na:1.8.0_291] at sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:479) ~[na:1.8.0_291] at sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:457) ~[na:1.8.0_291] at sun.security.ssl.TransportContext.dispatch(TransportContext.java:200) ~[na:1.8.0_291] at sun.security.ssl.SSLTransport.decode(SSLTransport.java:154) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1290) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1199) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:401) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:373) ~[na:1.8.0_291] at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:335) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:194) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:101) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:308) ~[mysql-connector-java-8.0.27.jar:8.0.27] ... 92 common frames omitted Caused by: java.security.cert.CertificateNotYetValidException: NotBefore: Sun Dec 19 02:30:18 CST 2021 at sun.security.x509.CertificateValidity.valid(CertificateValidity.java:273) ~[na:1.8.0_291] at sun.security.x509.X509CertImpl.checkValidity(X509CertImpl.java:677) ~[na:1.8.0_291] at sun.security.x509.X509CertImpl.checkValidity(X509CertImpl.java:650) ~[na:1.8.0_291] at com.mysql.cj.protocol.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:388) ~[mysql-connector-java-8.0.27.jar:8.0.27] at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:1255) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:636) ~[na:1.8.0_291] ... 107 common frames omitted 2021-12-18 22:33:43.636 ERROR 6358 --- [nio-9091-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is 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. ### The error may exist in com/example/mapper/UserMapper.java (best guess) ### The error may involve com.example.mapper.UserMapper.selectByPrimaryKey ### The error occurred while executing a query ### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is 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.] with root cause java.security.cert.CertificateNotYetValidException: NotBefore: Sun Dec 19 02:30:18 CST 2021 at sun.security.x509.CertificateValidity.valid(CertificateValidity.java:273) ~[na:1.8.0_291] at sun.security.x509.X509CertImpl.checkValidity(X509CertImpl.java:677) ~[na:1.8.0_291] at sun.security.x509.X509CertImpl.checkValidity(X509CertImpl.java:650) ~[na:1.8.0_291] at com.mysql.cj.protocol.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:388) ~[mysql-connector-java-8.0.27.jar:8.0.27] at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:1255) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:636) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.onCertificate(CertificateMessage.java:471) ~[na:1.8.0_291] at sun.security.ssl.CertificateMessage$T12CertificateConsumer.consume(CertificateMessage.java:367) ~[na:1.8.0_291] at sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:376) ~[na:1.8.0_291] at sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:479) ~[na:1.8.0_291] at sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:457) ~[na:1.8.0_291] at sun.security.ssl.TransportContext.dispatch(TransportContext.java:200) ~[na:1.8.0_291] at sun.security.ssl.SSLTransport.decode(SSLTransport.java:154) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1290) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1199) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:401) ~[na:1.8.0_291] at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:373) ~[na:1.8.0_291] at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:335) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:194) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:101) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:308) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:203) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1369) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-java-8.0.27.jar:8.0.27] at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:364) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:476) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:561) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) ~[HikariCP-4.0.3.jar:na] at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) ~[HikariCP-4.0.3.jar:na] at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:159) ~[spring-jdbc-5.3.13.jar:5.3.13] at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:117) ~[spring-jdbc-5.3.13.jar:5.3.13] at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80) ~[spring-jdbc-5.3.13.jar:5.3.13] at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82) ~[mybatis-spring-1.3.2.jar:1.3.2] at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68) ~[mybatis-spring-1.3.2.jar:1.3.2] at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:338) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77) ~[mybatis-3.4.6.jar:3.4.6] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_291] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_291] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_291] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_291] at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433) ~[mybatis-spring-1.3.2.jar:1.3.2] at com.sun.proxy.$Proxy58.selectOne(Unknown Source) ~[na:na] at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:166) ~[mybatis-spring-1.3.2.jar:1.3.2] at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:83) ~[mybatis-3.4.6.jar:3.4.6] at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59) ~[mybatis-3.4.6.jar:3.4.6] at com.sun.proxy.$Proxy66.selectByPrimaryKey(Unknown Source) ~[na:na] at com.example.service.impl.UserServiceImpl.selectById(UserServiceImpl.java:22) ~[classes/:na] at com.example.controller.UserController.selectById(UserController.java:24) ~[classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_291] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_291] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_291] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_291] at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.13.jar:5.3.13] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.13.jar:5.3.13] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.13.jar:5.3.13] at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.55.jar:4.0.FR] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.13.jar:5.3.13] at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.55.jar:4.0.FR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.13.jar:5.3.13] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.13.jar:5.3.13] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.13.jar:5.3.13] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.13.jar:5.3.13] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.13.jar:5.3.13] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.13.jar:5.3.13] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1722) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.55.jar:9.0.55] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.55.jar:9.0.55] at java.lang.Thread.run(Thread.java:748) [na:1.8.0_291]
application.yml 中数据库连接配置：
server: port: 9091 spring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://192.168.31.101:3306/springcloud username: root password: KevinWu123! mybatis: type-aliases-package: com.example.user.pojo logging: level: com.example.mapper.*: debug
项目启动时，正常，postman 调接口报上述错误，百度了好多，也试了好多，发现还是不行，于是对比了一下正常配置，结合 博客（https://blog.csdn.net/liangllhahaha/article/details/89821006） 的这张图
发现，少了一个 useSSL=false 加上去之后，完整 url：
jdbc:mysql://192.168.31.101:3306/springcloud?useSSL=false
再次尝试，成功了，对自己有点无语