spring - @ComponentScanning-Error 在 Spring Boot 应用程序中使用 IntelliJ 而不是 Eclipse

Question

我正在开发一个 Spring Boot 应用程序，它使用 Maven 进行构建管理。我已将此应用程序导入到 IntelliJ IDEA Ultimate 16.1。如果我运行我的 main 类，我得到以下错误:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.2.3.RELEASE)

Appl - 2016-09-01 08:04:31,642 [main] INFO  c.w.application.Application -  -  - Starting Application on mycomputer with PID 23345 (/pathToApplication/target/classes started by user in /pathtoapplication)
Appl - 2016-09-01 08:04:31,742 [main] DEBUG c.w.application.Application -  -  - Running with Spring Boot v1.2.3.RELEASE, Spring v4.1.6.RELEASE
Appl - 2016-09-01 08:04:38,519 [main] ERROR o.s.boot.SpringApplication -  -  - Application startup failed
java.lang.IllegalStateException: Could not evaluate condition on org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration#propertySourcesPlaceholderConfigurer due to internal class not found. This can happen if you are @ComponentScanning a springframework package (e.g. if you put a @ComponentScan in the default package by mistake)
    at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:51) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:102) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForBeanMethod(ConfigurationClassBeanDefinitionReader.java:190) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:148) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:124) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:318) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:239) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:254) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:94) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:606) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:462) ~[spring-context-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:686) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:320) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:957) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:946) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at com.applicationpackage.application.Application.main(Application.java:43) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_25]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_25]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_25]
    at java.lang.reflect.Method.invoke(Method.java:483) ~[na:1.8.0_25]
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]
Caused by: java.lang.NoClassDefFoundError: javax/servlet/Filter
    at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_25]
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2693) ~[na:1.8.0_25]
    at java.lang.Class.getDeclaredMethods(Class.java:1967) ~[na:1.8.0_25]
    at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:571) ~[spring-core-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:488) ~[spring-core-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:474) ~[spring-core-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.util.ReflectionUtils.getUniqueDeclaredMethods(ReflectionUtils.java:534) ~[spring-core-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod(AbstractAutowireCapableBeanFactory.java:677) ~[spring-beans-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:621) ~[spring-beans-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:591) ~[spring-beans-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1397) ~[spring-beans-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:968) ~[spring-beans-4.1.6.RELEASE.jar:4.1.6.RELEASE]
    at org.springframework.boot.autoconfigure.condition.BeanTypeRegistry$OptimizedBeanTypeRegistry.addBeanTypeForNonAliasDefinition(BeanTypeRegistry.java:257) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.BeanTypeRegistry$OptimizedBeanTypeRegistry.addBeanType(BeanTypeRegistry.java:246) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.BeanTypeRegistry$OptimizedBeanTypeRegistry.getNamesForType(BeanTypeRegistry.java:227) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.collectBeanNamesForType(OnBeanCondition.java:158) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:147) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchingBeans(OnBeanCondition.java:119) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchOutcome(OnBeanCondition.java:94) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:45) ~[spring-boot-autoconfigure-1.2.3.RELEASE.jar:1.2.3.RELEASE]
    ... 20 common frames omitted
Caused by: java.lang.ClassNotFoundException: javax.servlet.Filter
    at java.net.URLClassLoader$1.run(URLClassLoader.java:372) ~[na:1.8.0_25]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361) ~[na:1.8.0_25]
    at java.security.AccessController.doPrivileged(Native Method) ~[na:1.8.0_25]
    at java.net.URLClassLoader.findClass(URLClassLoader.java:360) ~[na:1.8.0_25]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_25]
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) ~[na:1.8.0_25]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_25]
    ... 40 common frames omitted
...

此方法的代码(包括上述消息中的错误点Application.java line 43)是:

@EnableAutoConfiguration
@ComponentScan("com.applicationpackage")
@SpringBootApplication
@EnableScheduling
public class Application extends WebMvcConfigurerAdapter {

  private static ConfigurableApplicationContext context;
    @Autowired
    private ServletContext servletContext;
  public static void main(String[] args) throws Exception {
        Application.context = SpringApplication.run(Application.class, args);
        Application.context.registerShutdownHook();
  }
  ...
}

显示的这行代码没有快速提示或错误。

如果我将它导入到 Eclipse Neo，它可以正常运行并且我可以访问我的网络应用程序。如果我运行 Maven install(例如，在 IntelliJ 之外)，那么该应用程序也会针对某些测试用例启动。所以看起来错误是由 IntelliJ 的设置引起的。在 project structure 菜单中没有显示任何问题，Spring Application Context 充满了 Application(没有显示“context-less classes”)。

Answer 1

你可以试试这个:

选择:文件->项目结构->模块->依赖

找到:tomcat-embed-core(默认提供这个jar包，改成编译)