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

    这篇文章分享一下Springboot整合Elasticsearch时遇到的一个问题，项目正常启动，但是查询数据库的时候发生了一个异常java.sql.SQLException: com.mysql.cj.jdbc.Driver

    1. java.sql.SQLException: com.mysql.cj.jdbc.Driver
    2. 	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:625) ~[druid-1.1.21.jar:1.1.21]
    3. 	at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:897) [druid-1.1.21.jar:1.1.21]
    4. 	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1376) [druid-1.1.21.jar:1.1.21]
    5. 	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1372) [druid-1.1.21.jar:1.1.21]
    6. 	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:109) [druid-1.1.21.jar:1.1.21]
    7. 	at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158) [spring-jdbc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    8. 	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116) [spring-jdbc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    9. 	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79) [spring-jdbc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    10. 	at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:80) [mybatis-spring-2.0.7.jar:2.0.7]
    11. 	at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67) [mybatis-spring-2.0.7.jar:2.0.7]
    12. 	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337) [mybatis-3.5.9.jar:3.5.9]
    13. 	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86) [mybatis-3.5.9.jar:3.5.9]
    14. 	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) [mybatis-3.5.9.jar:3.5.9]
    15. 	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325) [mybatis-3.5.9.jar:3.5.9]
    16. 	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) [mybatis-3.5.9.jar:3.5.9]
    17. 	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) [mybatis-3.5.9.jar:3.5.9]
    18. 	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:89) [mybatis-3.5.9.jar:3.5.9]
    19. 	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:151) [mybatis-3.5.9.jar:3.5.9]
    20. 	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:145) [mybatis-3.5.9.jar:3.5.9]
    21. 	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140) [mybatis-3.5.9.jar:3.5.9]
    22. 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_152]
    23. 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_152]
    24. 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_152]
    25. 	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_152]
    26. 	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:427) [mybatis-spring-2.0.7.jar:2.0.7]
    27. 	at com.sun.proxy.$Proxy56.selectList(Unknown Source) [na:na]
    28. 	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:224) [mybatis-spring-2.0.7.jar:2.0.7]
    29. 	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:147) [mybatis-3.5.9.jar:3.5.9]
    30. 	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:80) [mybatis-3.5.9.jar:3.5.9]
    31. 	at org.apache.ibatis.binding.MapperProxy$PlainMethodInvoker.invoke(MapperProxy.java:145) [mybatis-3.5.9.jar:3.5.9]
    32. 	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:86) [mybatis-3.5.9.jar:3.5.9]
    33. 	at com.sun.proxy.$Proxy57.selectAll(Unknown Source) [na:na]
    34. 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_152]
    35. 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_152]
    36. 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_152]
    37. 	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_152]
    38. 	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) [spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    39. 	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198) [spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    40. 	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) [spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    41. 	at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) [spring-tx-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    42. 	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) [spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    43. 	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) [spring-aop-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    44. 	at com.sun.proxy.$Proxy58.selectAll(Unknown Source) [na:na]
    45. 	at com.example.elasticsearch.controller.SongController.list(SongController.java:28) [classes/:na]
    46. 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_152]
    47. 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_152]
    48. 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_152]
    49. 	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_152]
    50. 	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    51. 	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    52. 	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    53. 	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    54. 	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    55. 	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    56. 	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    57. 	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    58. 	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    59. 	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    60. 	at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) [tomcat-embed-core-9.0.38.jar:4.0.FR]
    61. 	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    62. 	at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) [tomcat-embed-core-9.0.38.jar:4.0.FR]
    63. 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [tomcat-embed-core-9.0.38.jar:9.0.38]
    64. 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.38.jar:9.0.38]
    65. 	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.38.jar:9.0.38]
    66. 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.38.jar:9.0.38]
    67. 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.38.jar:9.0.38]
    68. 	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    69. 	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    70. 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.38.jar:9.0.38]
    71. 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.38.jar:9.0.38]
    72. 	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    73. 	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    74. 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.38.jar:9.0.38]
    75. 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.38.jar:9.0.38]
    76. 	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    77. 	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
    78. 	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.38.jar:9.0.38]
    79. 	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.38.jar:9.0.38]
    80. 	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.38.jar:9.0.38]
    81. 	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.38.jar:9.0.38]
    82. 	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.38.jar:9.0.38]
    83. 	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.38.jar:9.0.38]
    84. 	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.38.jar:9.0.38]
    85. 	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.38.jar:9.0.38]
    86. 	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.38.jar:9.0.38]
    87. 	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.38.jar:9.0.38]
    88. 	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.38.jar:9.0.38]
    89. 	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.38.jar:9.0.38]
    90. 	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) [tomcat-embed-core-9.0.38.jar:9.0.38]
    91. 	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.38.jar:9.0.38]
    92. 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_152]
    93. 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_152]
    94. 	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.38.jar:9.0.38]
    95. 	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_152]
    96. Caused by: java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
    97. 	at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_152]
    98. 	at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_152]
    99. 	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) ~[na:1.8.0_152]
    100. 	at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_152]
    101. 	at java.lang.Class.forName0(Native Method) ~[na:1.8.0_152]
    102. 	at java.lang.Class.forName(Class.java:264) ~[na:1.8.0_152]
    103. 	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:623) ~[druid-1.1.21.jar:1.1.21]
    104. 	... 93 common frames omitted

    通过断点发现加载数据库驱动的时候传进来的类加载器居然是null，惊呆了我的小伙伴，不知道看这篇文章的童鞋有没有遇到过这种问题，反正我是第一次遇到。

    最后发现原因让人哭笑不得，居然是没有导入jdbc的依赖。

    最后在pom.xml文件中添加依赖，然后刷新Maven，问题就解决了。

    1.     <properties>
    2.         <java.version>1.8java.version>
    3.         <mysql.version>8.0.28mysql.version>
    4.     properties>
    5.   
    6.     <dependencies>        
    7.         <dependency>
    8.             <groupId>mysqlgroupId>
    9.             <artifactId>mysql-connector-javaartifactId>
    10.             <version>${mysql.version}version>
    11.         dependency>
    12.     <dependencies>

    总结：以前会直接把其他项目上的依赖批量复制过去，这次因为整合elasticsearch，只是想把mysql里的数据导入elasticsearch，所以用不到那么多依赖，因此是一个个复制的，mybatis的都复制过去了，但是把mysql给忘了。

  • 相关阅读:
    REASONING ON GRAPHS: FAITHFUL AND INTERPRETABLE LARGE LANGUAGE MODEL REASONING
    决策树的优缺点
    机器学习笔记：Huber Loss & smooth L1 loss
    并查集详解（原理+代码实现+应用）
    Python- socket编程
    Vue2和Vue3的路由跳转及路由传参
    JSP自定义标签
    90后小伙以这196道MySQL面试题，实力吊打面试官，生生挤进大厂
    Citus 分布式 PostgreSQL 集群 - SQL Reference(创建和修改分布式表 DDL)
    冷热电气多能互补的微能源网鲁棒优化调度(Matlab代码实现）
  • 原文地址：https://blog.csdn.net/heyl163_/article/details/132641609