springboot：解决分页插件ClassNotFoundException

报错：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration': Post-processing of merged bean definition failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration] from ClassLoader [sun.misc.Launcher$AppClassLoader@2f4d3709]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:558) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:503) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at com.lee.www.DemoApplication.main(DemoApplication.java:14) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]
Caused by: java.lang.IllegalStateException: Failed to introspect Class [com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration] from ClassLoader [sun.misc.Launcher$AppClassLoader@2f4d3709]
at org.springframework.util.ReflectionUtils.getDeclaredFields(ReflectionUtils.java:758) ~[spring-core-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.util.ReflectionUtils.doWithLocalFields(ReflectionUtils.java:690) ~[spring-core-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.buildResourceMetadata(CommonAnnotationBeanPostProcessor.java:355) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.findResourceMetadata(CommonAnnotationBeanPostProcessor.java:339) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(CommonAnnotationBeanPostProcessor.java:298) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:1022) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
... 20 common frames omitted
Caused by: java.lang.NoClassDefFoundError: Lorg/springframework/boot/bind/RelaxedPropertyResolver;
at java.lang.Class.getDeclaredFields0(Native Method) ~[na:1.8.0_161]
at java.lang.Class.privateGetDeclaredFields(Class.java:2583) ~[na:1.8.0_161]
at java.lang.Class.getDeclaredFields(Class.java:1916) ~[na:1.8.0_161]
at org.springframework.util.ReflectionUtils.getDeclaredFields(ReflectionUtils.java:753) ~[spring-core-5.0.7.RELEASE.jar:5.0.7.RELEASE]
... 26 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.bind.RelaxedPropertyResolver
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_161]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_161]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) ~[na:1.8.0_161]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_161]
... 30 common frames omitted

重点是ClassNotFoundException: org.springframework.boot.bind.RelaxedPropertyResolver。

原版本为：

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.2</version>
</dependency>

升级为1.2.3即可：

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.3</version>
</dependency>