Java 在SpringBoot中使用@ComponentScan会导致错误

我已经构建了一个示例Spring引导应用程序，并且没有启用它。在学习本教程时，有必要启用@ComponentScan。但启用后，应用程序将不会启动并引发以下异常：

java.lang.IllegalStateException: Unable to load cache item
    at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:79) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:134) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:319) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:569) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.proxy.Enhancer.createClass(Enhancer.java:416) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer.createClass(ConfigurationClassEnhancer.java:137) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer.enhance(ConfigurationClassEnhancer.java:109) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.enhanceConfigurationClasses(ConfigurationClassPostProcessor.java:429) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanFactory(ConfigurationClassPostProcessor.java:263) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:286) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:130) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) ~[spring-context-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.1.RELEASE.jar!/:2.2.1.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.1.RELEASE.jar!/:2.2.1.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.1.RELEASE.jar!/:2.2.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.1.RELEASE.jar!/:2.2.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.1.RELEASE.jar!/:2.2.1.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.1.RELEASE.jar!/:2.2.1.RELEASE]
    at hello.Application.main(Application.java:17) [classes!/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_232]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_232]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_232]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_232]
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [gs-spring-boot-0.1.0.jar:na]
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [gs-spring-boot-0.1.0.jar:na]
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:51) [gs-spring-boot-0.1.0.jar:na]
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:52) [gs-spring-boot-0.1.0.jar:na]
Caused by: java.lang.NoClassDefFoundError: org/apache/log4j/Logger
    at asset.pipeline.springboot.AssetPipelineService.<clinit>(AssetPipelineService.groovy) ~[asset-pipeline-spring-boot-3.0.10.jar!/:na]
    at java.lang.Class.forName0(Native Method) ~[na:1.8.0_232]
    at java.lang.Class.forName(Class.java:348) ~[na:1.8.0_232]
    at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:563) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:363) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:582) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:110) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:108) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_232]
    at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61) ~[spring-core-5.2.1.RELEASE.jar!/:5.2.1.RELEASE]
    ... 28 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382) ~[na:1.8.0_232]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418) ~[na:1.8.0_232]
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:92) ~[gs-spring-boot-0.1.0.jar:na]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[na:1.8.0_232]
    ... 39 common frames omitted

src/main/java/hello/HelloController.java

格雷德尔先生

---

如本教程所述，您是否在本地运行groovy？注意：资产管道在开发运行时模式下运行时需要groovy。谢谢。我添加了groovy，但现在得到了不同的错误消息。我已经更新了上面的例子。这个应用对我来说很好。使用./gradlew bootRun

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

// @SpringBootApplication
@Configuration
@EnableAutoConfiguration
@ComponentScan({"hello","asset.pipeline.springboot"})
public class Application {

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }
}

package hello;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

  @RequestMapping("/")
  public String index() {
    return "Greetings from Spring Boot!";
  }

}

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath("org.springframework.boot:spring-boot-gradle-plugin:2.2.1.RELEASE")
    classpath "com.bertramlabs.plugins:asset-pipeline-gradle:3.0.10"
  }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
apply plugin: 'checkstyle'
apply plugin: 'groovy'
apply plugin: 'com.bertramlabs.asset-pipeline'

bootJar {
  baseName = 'gs-spring-boot'
  version = '0.1.0'
}

repositories {
  mavenCentral()
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

dependencies {
  compile("org.springframework.boot:spring-boot-starter-web")
  compile("org.springframework.boot:spring-boot-starter-actuator")
  compile('org.codehaus.groovy:groovy')
  testCompile("junit:junit")
  testCompile("org.springframework.boot:spring-boot-starter-test")
  runtime 'com.bertramlabs.plugins:asset-pipeline-spring-boot:3.0.10'
  assets 'com.bertramlabs.plugins:sass-asset-pipeline:3.0.10'
}