Spring boot启动失败，提示找不到类：java.lang.NoClassDefFoundError: org/springframework/aop/framework/AopProxyUtils

　　详细报错日志如下：

D:DevJavajdk1.8.0_102injava.exe -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true "-javaagent:D:DevIntelliJ IDEA 2018.3.5libidea_rt.jar=49426:D:DevIntelliJ IDEA 2018.3.5in" -Dfile.encoding=UTF-8 -classpath D:DevJavajdk1.8.0_102jrelibcharsets.jar;D:DevJavajdk1.8.0_102jrelibdeploy.jar;D:DevJavajdk1.8.0_102jrelibextaccess-bridge-64.jar;D:DevJavajdk1.8.0_102jrelibextcldrdata.jar;D:DevJavajdk1.8.0_102jrelibextdnsns.jar;D:DevJavajdk1.8.0_102jrelibextjaccess.jar;D:DevJavajdk1.8.0_102jrelibextjfxrt.jar;D:DevJavajdk1.8.0_102jrelibextlocaledata.jar;D:DevJavajdk1.8.0_102jrelibext
ashorn.jar;D:DevJavajdk1.8.0_102jrelibextsunec.jar;D:DevJavajdk1.8.0_102jrelibextsunjce_provider.jar;D:DevJavajdk1.8.0_102jrelibextsunmscapi.jar;D:DevJavajdk1.8.0_102jrelibextsunpkcs11.jar;D:DevJavajdk1.8.0_102jrelibextzipfs.jar;D:DevJavajdk1.8.0_102jrelibjavaws.jar;D:DevJavajdk1.8.0_102jrelibjce.jar;D:DevJavajdk1.8.0_102jrelibjfr.jar;D:DevJavajdk1.8.0_102jrelibjfxswt.jar;D:DevJavajdk1.8.0_102jrelibjsse.jar;D:DevJavajdk1.8.0_102jrelibmanagement-agent.jar;D:DevJavajdk1.8.0_102jrelibplugin.jar;D:DevJavajdk1.8.0_102jrelib
esources.jar;D:DevJavajdk1.8.0_102jrelib
t.jar;E:workspacesubtitle-stub	argetclasses;E:Userswulf.m2
epositorycomalibabafastjson1.2.21fastjson-1.2.21.jar;E:Userswulf.m2
epositorycomsquareupokhttp3okhttp4.2.2okhttp-4.2.2.jar;E:Userswulf.m2
epositorycomsquareupokiookio2.2.2okio-2.2.2.jar;E:Userswulf.m2
epositoryorgjetbrainskotlinkotlin-stdlib1.3.71kotlin-stdlib-1.3.71.jar;E:Userswulf.m2
epositoryorgjetbrainskotlinkotlin-stdlib-common1.3.71kotlin-stdlib-common-1.3.71.jar;E:Userswulf.m2
epositoryorgjetbrainsannotations13.0annotations-13.0.jar;E:Userswulf.m2
epositorychqoslogbacklogback-classic1.2.3logback-classic-1.2.3.jar;E:Userswulf.m2
epositorychqoslogbacklogback-core1.2.3logback-core-1.2.3.jar;E:Userswulf.m2
epositoryorgslf4jslf4j-api1.7.30slf4j-api-1.7.30.jar;E:Userswulf.m2
epositoryorgprojectlomboklombok1.18.8lombok-1.18.8.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-starter-web2.2.6.RELEASEspring-boot-starter-web-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-starter2.2.6.RELEASEspring-boot-starter-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot2.2.6.RELEASEspring-boot-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-autoconfigure2.2.6.RELEASEspring-boot-autoconfigure-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-starter-logging2.2.6.RELEASEspring-boot-starter-logging-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryorgapachelogginglog4jlog4j-to-slf4j2.12.1log4j-to-slf4j-2.12.1.jar;E:Userswulf.m2
epositoryorgapachelogginglog4jlog4j-api2.12.1log4j-api-2.12.1.jar;E:Userswulf.m2
epositoryorgslf4jjul-to-slf4j1.7.30jul-to-slf4j-1.7.30.jar;E:Userswulf.m2
epositoryjakartaannotationjakarta.annotation-api1.3.5jakarta.annotation-api-1.3.5.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-core5.2.5.RELEASEspring-core-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-jcl5.2.5.RELEASEspring-jcl-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgyamlsnakeyaml1.25snakeyaml-1.25.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-starter-json2.2.6.RELEASEspring-boot-starter-json-2.2.6.RELEASE.jar;E:Userswulf.m2
epositorycomfasterxmljacksoncorejackson-databind2.10.3jackson-databind-2.10.3.jar;E:Userswulf.m2
epositorycomfasterxmljacksoncorejackson-annotations2.10.3jackson-annotations-2.10.3.jar;E:Userswulf.m2
epositorycomfasterxmljacksoncorejackson-core2.10.3jackson-core-2.10.3.jar;E:Userswulf.m2
epositorycomfasterxmljacksondatatypejackson-datatype-jdk82.10.3jackson-datatype-jdk8-2.10.3.jar;E:Userswulf.m2
epositorycomfasterxmljacksondatatypejackson-datatype-jsr3102.10.3jackson-datatype-jsr310-2.10.3.jar;E:Userswulf.m2
epositorycomfasterxmljacksonmodulejackson-module-parameter-names2.10.3jackson-module-parameter-names-2.10.3.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-starter-tomcat2.2.6.RELEASEspring-boot-starter-tomcat-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryorgapache	omcatembed	omcat-embed-core9.0.33	omcat-embed-core-9.0.33.jar;E:Userswulf.m2
epositoryorgapache	omcatembed	omcat-embed-el9.0.33	omcat-embed-el-9.0.33.jar;E:Userswulf.m2
epositoryorgapache	omcatembed	omcat-embed-websocket9.0.33	omcat-embed-websocket-9.0.33.jar;E:Userswulf.m2
epositoryorgspringframeworkootspring-boot-starter-validation2.2.6.RELEASEspring-boot-starter-validation-2.2.6.RELEASE.jar;E:Userswulf.m2
epositoryjakartavalidationjakarta.validation-api2.0.2jakarta.validation-api-2.0.2.jar;E:Userswulf.m2
epositoryorghibernatevalidatorhibernate-validator6.0.18.Finalhibernate-validator-6.0.18.Final.jar;E:Userswulf.m2
epositoryorgjbossloggingjboss-logging3.4.1.Finaljboss-logging-3.4.1.Final.jar;E:Userswulf.m2
epositorycomfasterxmlclassmate1.5.1classmate-1.5.1.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-web5.2.5.RELEASEspring-web-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-beans5.2.5.RELEASEspring-beans-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-webmvc5.2.5.RELEASEspring-webmvc-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-aop5.2.5.RELEASEspring-aop-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-context5.2.5.RELEASEspring-context-5.2.5.RELEASE.jar;E:Userswulf.m2
epositoryorgspringframeworkspring-expression5.2.5.RELEASEspring-expression-5.2.5.RELEASE.jar;E:Userswulf.m2
epositorycommons-codeccommons-codec1.13commons-codec-1.13.jar com.lxy.DemoApplication
17:34:11.998 [main] INFO org.springframework.core.KotlinDetector - Kotlin reflection implementation not found at runtime, related features won't be available.
Exception in thread "main" java.lang.IllegalArgumentException: Cannot instantiate interface org.springframework.boot.SpringApplicationRunListener : org.springframework.boot.context.event.EventPublishingRunListener
    at org.springframework.boot.SpringApplication.createSpringFactoriesInstances(SpringApplication.java:445)
    at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:427)
    at org.springframework.boot.SpringApplication.getRunListeners(SpringApplication.java:416)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:304)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at com.lxy.DemoApplication.main(DemoApplication.java:9)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.context.event.EventPublishingRunListener]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/aop/framework/AopProxyUtils
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:217)
    at org.springframework.boot.SpringApplication.createSpringFactoriesInstances(SpringApplication.java:441)
    ... 6 more
Caused by: java.lang.NoClassDefFoundError: org/springframework/aop/framework/AopProxyUtils
    at org.springframework.context.event.AbstractApplicationEventMulticaster.addApplicationListener(AbstractApplicationEventMulticaster.java:110)
    at org.springframework.boot.context.event.EventPublishingRunListener.<init>(EventPublishingRunListener.java:59)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:204)
    ... 7 more
Caused by: java.lang.ClassNotFoundException: org.springframework.aop.framework.AopProxyUtils
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 14 more

Process finished with exit code 1

　　既然说类找不到，那么我们就去找一下吧，去哪找呢？在IDEA中看依赖的包，很明显，跟切面相关的就这个了：

　　我们打开spring-aop-5.2.5.RELEASE.jar，确认AopProxyUtils.class存在：

 　　很明显，jar包里面没有东西，也可以去maven本地仓库看看：

 　　发现jar包大小不对。怎么办？把本地仓库的空jar包删掉，重新跑maven就可以再次下载

D:DevJavajdk1.8.0_102injava.exe -Dmaven.multiModuleProjectDirectory=E:workspacesubtitle-stub -Dmaven.home=D:Devapache-maven-3.3.9 -Dclassworlds.conf=D:Devapache-maven-3.3.9inm2.conf "-javaagent:D:DevIntelliJ IDEA 2018.3.5libidea_rt.jar=50888:D:DevIntelliJ IDEA 2018.3.5in" -Dfile.encoding=UTF-8 -classpath D:Devapache-maven-3.3.9ootplexus-classworlds-2.5.2.jar org.codehaus.classworlds.Launcher -Didea.version=2018.3.5 -s D:Devapache-maven-3.3.9confsettings.xml compile
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building subtitle-stub 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
Downloading: http://maven.aliyun.com/nexus/content/groups/public/org/springframework/spring-aop/5.2.5.RELEASE/spring-aop-5.2.5.RELEASE.jar
Downloaded: http://maven.aliyun.com/nexus/content/groups/public/org/springframework/spring-aop/5.2.5.RELEASE/spring-aop-5.2.5.RELEASE.jar (364 KB at 211.9 KB/sec)
[INFO] 
[INFO] --- maven-resources-plugin:3.1.0:resources (default-resources) @ subtitle-stub ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] Copying 1 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ subtitle-stub ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 9 source files to E:workspacesubtitle-stub	argetclasses
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7.713 s
[INFO] Finished at: 2020-04-29T17:58:49+08:00
[INFO] Final Memory: 31M/277M
[INFO] ------------------------------------------------------------------------

Process finished with exit code 0

　　因为我们删掉了老jar包，这时如果打开IDEA的项目结构 -> 模块，会发现有红叉叉，重新指定一下新jar包即可：

 　　

　　点击右边的笔进行编辑：

 　　

　　选中Class后点击减号，删掉后点加号指定maven仓库的jar包：

 　　

　　一路OK回去，再启动Spring Boot一切正常了。