Java Spring Boot - spring-boot-starter-tomcat 依赖项不适用于在本地运行时提供的范围

Question

我正在开发一个需要在我们客户的 Tomcat 服务器上运行的 Java Spring Boot 应用程序。这个应用程序基本上包含一个 REST API，为我们的前端提供文件。

在我们第一次在客户端服务器上进行部署测试之前，在本地运行此应用程序非常顺利。我们不得不重构我们的代码并向项目的 pom.xml 添加一些依赖项。这最终奏效了(有点)。

现在我想再次开始本地开发，但发现我的代码无法使用我之前使用的相同运行配置运行。在执行 mvn spring-boot:run 时工作正常，我需要 IntelliJ 的调试功能才能继续开发。

经过一些搜索，我在我的 pom.xml 中发现了问题:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>

虽然<scope>provided</scope>必须在 tomcat 上运行生成的 WAR 文件，我给出了一些在本地运行的问题。更具体地说，产生了以下错误:

java.lang.IllegalStateException: ApplicationEventMulticaster not initialized - call 'refresh' before multicasting events via the context: org.springframework.context.annotation.AnnotationConfigApplicationContext@2a693f59: startup date [Mon Nov 06 10:52:25 CET 2017]; root of context hierarchy
at Org.springframework.context.support.AbstractApplicationContext.getApplicationEventMulticaster(AbstractApplicationContext.java:414) [spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.ApplicationListenerDetector.postProcessBeforeDestruction(ApplicationListenerDetector.java:97) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.DisposableBeanAdapter.destroy(DisposableBeanAdapter.java:253) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroyBean(DefaultSingletonBeanRegistry.java:578) [spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingleton(DefaultSingletonBeanRegistry.java:554) [spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingleton(DefaultListableBeanFactory.java:961) [spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingletons(DefaultSingletonBeanRegistry.java:523) [spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.destroySingletons(FactoryBeanRegistrySupport.java:230) [spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingletons(DefaultListableBeanFactory.java:968) [spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.destroyBeans(AbstractApplicationContext.java:1030) [spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:556) [spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at be.craftworkz.engima.acerta.boilerplate.BoilerplateApplication.main(BoilerplateApplication.java:23) [classes/:na]

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [be.craftworkz.engima.acerta.boilerplate.BoilerplateApplication]; nested exception is java.lang.IllegalStateException: Failed to introspect annotated methods on class org.springframework.boot.web.support.SpringBootServletInitializer
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:181) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:308) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:228) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:272) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:92) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:687) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:525) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at be.craftworkz.engima.acerta.boilerplate.BoilerplateApplication.main(BoilerplateApplication.java:23) [classes/:na]

Caused by: java.lang.IllegalStateException: Failed to introspect annotated methods on class org.springframework.boot.web.support.SpringBootServletInitializer
at org.springframework.core.type.StandardAnnotationMetadata.getAnnotatedMethods(StandardAnnotationMetadata.java:163) ~[spring-core-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.retrieveBeanMethodMetadata(ConfigurationClassParser.java:380) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:314) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:245) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:198) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:167) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
... 12 common frames omitted
Caused by: java.lang.NoClassDefFoundError: javax/servlet/ServletContext
at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_144]
at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) ~[na:1.8.0_144]
at java.lang.Class.getDeclaredMethods(Class.java:1975) ~[na:1.8.0_144]
at org.springframework.core.type.StandardAnnotationMetadata.getAnnotatedMethods(StandardAnnotationMetadata.java:152) ~[spring-core-4.3.12.RELEASE.jar:4.3.12.RELEASE]
... 17 common frames omitted

Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletContext
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_144]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[na:1.8.0_144]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_144]
... 21 common frames omitted

删除此 <scope>provided</scope>从我的依赖中解决了这个问题，但我不明白这里的问题是什么。因此，如果有人可以详细解释为什么会出现此错误，那就太棒了!我真的很想避免将来浪费时间在这类问题上，所以...

谢谢!

长话短说:Maven的依赖参数<scope>provided</scope>如何本地运行 Java Spring Boot 应用程序与在 Tomcat 服务器上远程运行 Java Spring Boot 应用程序有何影响？

Answer 1

provided scope 表示不用担心，这些类将在运行时存在，因此无需将它们包含在 WAR 中。

在完整的 tomcat 服务器中运行，您可以使用 provided 因为类(不在 WAR 中)存在。但是，在本地使用嵌入式 tomcat 运行时，它会失败，因为您说过不用担心 tomcat 类。

这意味着您不能对开发和生产使用相同的范围。您可以创建不同的 Maven profiles使用不同的范围，并使用“开发”配置文件进行本地开发。

那么无论何时进行本地开发，只要添加一个 -Pdev 就很容易了。