报错：java.sql.SQLException: com.mysql.cj.jdbc.Driver

在IDEA里用Spring Initializr创建了一个SpringBoot项目，mybatis链接mysql数据库时报以下错误

2019-09-23 15:23:19.211  INFO 4568 --- [nio-8888-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/demo]   : Initializing Spring DispatcherServlet 'dispatcherServlet'
2019-09-23 15:23:19.211  INFO 4568 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2019-09-23 15:23:19.219  INFO 4568 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 8 ms
2019-09-23 15:23:19.297 ERROR 4568 --- [nio-8888-exec-1] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} init error

java.sql.SQLException: com.mysql.cj.jdbc.Driver
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:574) ~[druid-1.1.0.jar:1.1.0]
	at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:750) [druid-1.1.0.jar:1.1.0]
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1122) [druid-1.1.0.jar:1.1.0]
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1118) [druid-1.1.0.jar:1.1.0]
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:104) [druid-1.1.0.jar:1.1.0]
	at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:157) [spring-jdbc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115) [spring-jdbc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78) [spring-jdbc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82) [mybatis-spring-2.0.0.jar:2.0.0]
	at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68) [mybatis-spring-2.0.0.jar:2.0.0]
	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:336) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:85) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141) [mybatis-3.5.0.jar:3.5.0]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_91]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_91]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_91]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_91]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433) [mybatis-spring-2.0.0.jar:2.0.0]
	at com.sun.proxy.$Proxy57.selectList(Unknown Source) [na:na]
	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:230) [mybatis-spring-2.0.0.jar:2.0.0]
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:144) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:77) [mybatis-3.5.0.jar:3.5.0]
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:58) [mybatis-3.5.0.jar:3.5.0]
	at com.sun.proxy.$Proxy58.getAllUser(Unknown Source) [na:na]
	at com.feifan.Service.UserServiceIpml.getAllUser(UserServiceIpml.java:17) [classes/:na]
	at com.feifan.Controller.DemoController.getAllUser(DemoController.java:25) [classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_91]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_91]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_91]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_91]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1039) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_91]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_91]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.24.jar:9.0.24]
	at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]
Caused by: java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_91]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_91]
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) ~[na:1.8.0_91]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_91]
	at java.lang.Class.forName0(Native Method) ~[na:1.8.0_91]
	at java.lang.Class.forName(Class.java:264) ~[na:1.8.0_91]
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:572) ~[druid-1.1.0.jar:1.1.0]
	... 85 common frames omitted

 

查了一下资料

mysql  5用的驱动是com.mysql.jdbc.Driver

mysql  6用的驱动是com.mysql.cj.jdbc.Driver

我的pom.xml里用的就是5.1.46，下载的jar也是5.1.46（整的我不是很确定5.1.46就是mysql 5了）

网友说“JDBC连接Mysql6 com.mysql.cj.jdbc.Driver， 需要指定时区serverTimezone:”

我就改成以下这样（这办法对我不适用）

spring.datasource.url=jdbc:mysql:///test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8

我的解决办法：

把pom.xml中mysql的版本号去掉了，索性愿意下载什么版本随意了

至此，问题解决也不报错了。但是这不是解决问题的根本办法，如果项目要求指定mysql版本的话还是要搞明白的

 

后续找到原因了会持续更新，或者谁洞察其中原理了麻烦评论告知一下