成功解决报错Cannot find class [com.alibaba.druid.pool.DruidDataSource] for bean with name ‘dataSource‘

报错1： UnsatisfiedDependencyException报错，意思是创建’departmentService’的bean时发生错误。'departmentMapper’中存在不满足的依赖
报错2： CannotLoadBeanClassException报错，意思是bean’dataSource’找不到[com.alibaba.druid.pool.DruidDataSource]
报错3： ClassNotFoundException报错，意思是找不到[com.alibaba.druid.pool.DruidDataSource]

04-Jul-2022 14:59:51.250 警告 [RMI TCP Connection(3)-127.0.0.1] org.apache.tomcat.util.descriptor.web.WebXml.setVersion 未知版本字符串 [4.0]。将使用默认版本。
04-Jul-2022 14:59:51.851 信息 [RMI TCP Connection(3)-127.0.0.1] org.apache.jasper.servlet.TldScanner.scanJars 至少有一个JAR被扫描用于TLD但尚未包含TLD。 为此记录器启用调试日志记录，以获取已扫描但未在其中找到TLD的完整JAR列表。 在扫描期间跳过不需要的JAR可以缩短启动时间和JSP编译时间。
04-Jul-2022 14:59:51.885 信息 [RMI TCP Connection(3)-127.0.0.1] org.springframework.web.context.ContextLoader.initWebApplicationContext Root WebApplicationContext: initialization started
04-Jul-2022 14:59:52.288 警告 [RMI TCP Connection(3)-127.0.0.1] org.springframework.context.support.AbstractApplicationContext.refresh Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'departmentService': Unsatisfied dependency expressed through field 'departmentMapper'; nested exception is org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.alibaba.druid.pool.DruidDataSource] for bean with name 'dataSource' defined in class path resource [applicationContext.xml]; nested exception is java.lang.ClassNotFoundException: com.alibaba.druid.pool.DruidDataSource
04-Jul-2022 14:59:52.291 严重 [RMI TCP Connection(3)-127.0.0.1] org.springframework.web.context.ContextLoader.initWebApplicationContext Context initialization failedorg.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'departmentService': Unsatisfied dependency expressed through field 'departmentMapper'; nested exception is org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.alibaba.druid.pool.DruidDataSource] for bean with name 'dataSource' defined in class path resource [applicationContext.xml]; nested exception is java.lang.ClassNotFoundException: com.alibaba.druid.pool.DruidDataSourceat org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:659)at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639)at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:953)at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:401)at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:292)at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:103)at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4763)at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5232)at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:753)at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:727)at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:695)at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1775)at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)at java.base/java.lang.reflect.Method.invoke(Method.java:577)at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:291)at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:811)at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:802)at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:483)at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:431)at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)at java.base/java.lang.reflect.Method.invoke(Method.java:577)at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:291)at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:811)at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:802)at java.management/com.sun.jmx.remote.security.MBeanServerAccessController.invoke(MBeanServerAccessController.java:472)at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1472)at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1310)at java.base/java.security.AccessController.doPrivileged(AccessController.java:712)at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1412)at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)at java.base/java.lang.reflect.Method.invoke(Method.java:577)at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:360)at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)at java.base/java.security.AccessController.doPrivileged(AccessController.java:712)at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:598)at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:844)at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:721)at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:720)at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)at java.base/java.lang.Thread.run(Thread.java:833)Caused by: org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [com.alibaba.druid.pool.DruidDataSource] for bean with name 'dataSource' defined in class path resource [applicationContext.xml]; nested exception is java.lang.ClassNotFoundException: com.alibaba.druid.pool.DruidDataSourceat org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1542)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:704)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:674)at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1670)at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:570)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:550)at org.springframework.beans.factory.BeanFactoryUtils.beanNamesForTypeIncludingAncestors(BeanFactoryUtils.java:265)at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1555)at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1352)at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1309)at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656)... 56 moreCaused by: java.lang.ClassNotFoundException: com.alibaba.druid.pool.DruidDataSourceat org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1420)at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1228)at java.base/java.lang.Class.forName0(Native Method)at java.base/java.lang.Class.forName(Class.java:488)at java.base/java.lang.Class.forName(Class.java:467)at org.springframework.util.ClassUtils.forName(ClassUtils.java:284)at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:469)at org.springframework.beans.factory.support.AbstractBeanFactory.doResolveBeanClass(AbstractBeanFactory.java:1607)at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1534)... 66 more
04-Jul-2022 14:59:52.294 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal 一个或多个listeners启动失败，更多详细信息查看对应的容器日志文件
04-Jul-2022 14:59:52.316 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal 由于之前的错误，Context[]启动失败
[2022-07-04 02:59:52,332] Artifact coolmeeting:war: Error during artifact deployment. See server log for details.
04-Jul-2022 15:00:00.509 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory 把web 应用程序部署到目录 [D:\apache-tomcat-8.5.81\webapps\manager]
04-Jul-2022 15:00:00.595 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Web应用程序目录[D:\apache-tomcat-8.5.81\webapps\manager]的部署已在[85]毫秒内完成

遇到问题的第一反应，开心！！！

又可以进步啦！！！yeah~
像这么“短小"的bug怎么能难得了我！？

不得不说，Spring更新迭代的太快了，网上找到的解决方案大多是要添加jar包，可是人家视频教程里的up也没加啊，不服！

首个要解决的问题：
CannotLoadBeanClassException报错，意思是bean’dataSource’找不到[com.alibaba.druid.pool.DruidDataSource]

数据库连接池druid导入失败，可能原因：
1、可能是pom.xml中没有配置druid依赖
2、spring的xml配置有问题
3、pom.xml配置有问题

首先确实配置了druid依赖!

其次Spring的配置也没太大问题

最后检查pom.xml配置，可以采用右键项目/Maven/Reload project的方式，如果pom.xml中有语法问题或是配置问题会报错，从而对应去修改即可。

仔细检查发现读取xml配置的语法中少了，其次Mybatis配置错误

修改后再次Reload project

执行tomcat成功！
可以发现sping相关的配置有问题，大多还是出在pom.xml文件中，遇到报错不要慌，仔细检查检查即可。觉得本篇文章对您有用的话，点个👍哦！灰常感谢~