Spring Boot JPA项目启动报错：无法加载配置类求助

问题描述 #

我跟着教程搭建了一个基于Spring Boot JPA的简单CRUD项目，使用JDK18版本启动时，出现无法加载配置类net.guides.springboot2.crud.Application的错误，完整错误日志如下：

2022-10-25 18:11:09.510  INFO 12252 --- [           main] net.guides.springboot2.crud.Application  : Starting Application on DESKTOP-L7QADCR with PID 12252 (C:\Users\Seema\springboot-postgresql-hibernate-crud-example-main\springboot-postgresql-hibernate-crud-example-main\target\classes started by Seema in C:\Users\Seema\springboot-postgresql-hibernate-crud-example-main\springboot-postgresql-hibernate-crud-example-main)
2022-10-25 18:11:09.533  INFO 12252 --- [           main] net.guides.springboot2.crud.Application  : No active profile set, falling back to default profiles: default
2022-10-25 18:11:10.019  INFO 12252 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@4c12331b: startup date [Tue Oct 25 18:11:10 IST 2022]; root of context hierarchy
2022-10-25 18:11:19.081 ERROR 12252 --- [           main] o.s.boot.SpringApplication               : Application run failed

java.lang.IllegalStateException: Cannot load configuration class: net.guides.springboot2.crud.Application
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.enhanceConfigurationClasses(ConfigurationClassPostProcessor.java:414) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanFactory(ConfigurationClassPostProcessor.java:254) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:282) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:126) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:694) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:780) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:333) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1277) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1265) ~[spring-boot-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at net.guides.springboot2.crud.Application.main(Application.java:11) ~[classes/:na]
Caused by: java.lang.ExceptionInInitializerError: null
    at org.springframework.context.annotation.ConfigurationClassEnhancer.newEnhancer(ConfigurationClassEnhancer.java:122) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer.enhance(ConfigurationClassEnhancer.java:110) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.enhanceConfigurationClasses(ConfigurationClassPostProcessor.java:403) ~[spring-context-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    ... 12 common frames omitted
Caused by: org.springframework.cglib.core.CodeGenerationException: java.lang.reflect.InaccessibleObjectException-->Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @184f6be2
    at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:464) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:336) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:93) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:91) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na]
    at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:116) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:291) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.KeyFactory$Generator.create(KeyFactory.java:221) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.KeyFactory.create(KeyFactory.java:174) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.core.KeyFactory.create(KeyFactory.java:153) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    at org.springframework.cglib.proxy.Enhancer.<clinit>(Enhancer.java:73) ~[spring-core-5.0.9.RELEASE.jar:5.0.9.RELEASE]
    ... 15 common frames omitted
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @184f6be2
    at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354) ~[na:na]
    at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297) ~[na:na]
    at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:200) ~[na:na]
    at java.base/java.lang.reflect.Method.setAccessible(Method.java:194) ~[na:na]

错误原因 #

项目使用的Spring Boot 2.0.5.RELEASE对应Spring 5.0.9.RELEASE，该版本的Spring依赖的CGLIB库不支持JDK9及以上引入的模块系统（JPMS）。JDK18的模块安全机制会阻止CGLIB通过反射访问java.lang.ClassLoader的受保护方法，从而导致配置类加载失败。

解决方案 #

方案1：升级Spring Boot版本（推荐） #

Spring Boot 2.7.x及以上版本完全兼容JDK18，直接修改pom.xml中的Spring Boot父依赖版本：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.7.15</version> <!-- 或选择3.1.x及以上的稳定版本 -->
    <relativePath/>
</parent>

升级后Maven会自动同步兼容的Spring Data JPA、Hibernate等依赖版本，无需手动调整。

方案2：降级JDK版本 #

如果暂时不想升级框架，可以将JDK版本降级到Spring Boot 2.0.5支持的范围，比如JDK8或JDK10，这两个版本与该项目的依赖完全兼容，不会出现模块权限问题。

内容的提问来源于stack exchange，提问作者sachin lobo