今天在启动项目的时候，一直报错，意思是缺少了commons.pools的对象池类，信息如下：

ERROR SpringApplication Application run failed
 java.lang.IllegalStateException: Unable to load cache item
	at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:79)
	at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34)
	at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:134)
	at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319)
	at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:569)
	at org.springframework.cglib.proxy.Enhancer.createClass(Enhancer.java:416)
	at org.springframework.context.annotation.ConfigurationClassEnhancer.createClass(ConfigurationClassEnhancer.java:137)
	at org.springframework.context.annotation.ConfigurationClassEnhancer.enhance(ConfigurationClassEnhancer.java:109)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.enhanceConfigurationClasses(ConfigurationClassPostProcessor.java:423)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanFactory(ConfigurationClassPostProcessor.java:257)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:286)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:130)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
	at com.getech.iot.console.IotConsoleWebAppStart.main(IotConsoleWebAppStart.java:20)
Caused by: java.lang.NoClassDefFoundError: org/apache/commons/pool2/impl/GenericObjectPool
	at java.lang.Class.getDeclaredMethods0(Native Method)
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
	at java.lang.Class.getDeclaredMethods(Class.java:1975)
	at org.springframework.cglib.core.ReflectUtils.addAllMethods(ReflectUtils.java:451)
	at org.springframework.cglib.proxy.Enhancer.getMethods(Enhancer.java:632)
	at org.springframework.cglib.proxy.Enhancer.generateClass(Enhancer.java:667)
	at org.springframework.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33)
	at org.springframework.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
	at org.springframework.cglib.core.ClassLoaderAwareGeneratorStrategy.generate(ClassLoaderAwareGeneratorStrategy.java:57)
	at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:358)
	at org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:582)
	at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110)
	at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108)
	at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
	at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
	at java.util.concurrent.FutureTask.run(FutureTask.java)
	at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61)
	... 20 more
Caused by: java.lang.ClassNotFoundException: org.apache.commons.pool2.impl.GenericObjectPool
	at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:359)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
	... 37 more

然后点击通义灵码工具问了下，回答是缺少commons-pool2的包，如下：

尝试了下，在maven里面添加了上面的依赖

<dependency>
    <groupId>org.apache.commons</groupId>
     <artifactId>commons-pool2</artifactId>
     <version>2.6.2</version>
 </dependency>

然后一直启动还是报错，以为是版本号问题，试了几个不同版本似乎没有变化，于是尝试退出idea并清除缓存

重新打开idea，等待加载完成，启动不报错了，OK问题解决。