我使用spring boot框架上传文件，我想指定一个类的位置，然后我可以将文件上传到动态位置。 顺便说一句，奇怪的是这是在intellij中工作，但是在我执行了一个清洁和构建项目，然后运行后，它突然停止工作 主要应用：
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(SmartDustbinServiceApplication.class, args);
}
@Bean
MultipartConfigElement multipartConfigElement() {
MultipartConfigFactory factory = new MultipartConfigFactory();
factory.setLocation(PathKit.getWebRootPath());
return factory.createMultipartConfig();
}
并且PathKit类有这样的方法：
private static String detectWebRootPath() {
try {
String path = PathKit.class.getResource("/").toURI().getPath();
return new File(path).getParentFile().getParentFile().getCanonicalPath();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
然后在启动springboot项目时遇到以下异常;
2017-05-08 20:27:21.878 [main] ERROR
org.springframework.boot.SpringApplication - Application startup failed
org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to start embedded Tomcat
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:137)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:536)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151)
at com.locision.system.cgc.SmartDustbinServiceApplication.main(SmartDustbinServiceApplication.java:18)
Caused by: org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to start embedded Tomcat
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.initialize(TomcatEmbeddedServletContainer.java:123)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.<init>(TomcatEmbeddedServletContainer.java:84)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getTomcatEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:548)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:179)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:164)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:134)
... 8 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration': Bean instantiation via constructor failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration$$EnhancerBySpringCGLIB$$e04a54a4]: Constructor threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'multipartConfigElement' defined in com.locision.system.cgc.SmartDustbinServiceApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.servlet.MultipartConfigElement]: Factory method 'multipartConfigElement' threw exception; nested exception is java.lang.RuntimeException: java.lang.NullPointerException
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:279)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1193)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1095)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:372)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:234)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:215)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addServletContextInitializerBeans(ServletContextInitializerBeans.java:91)
at org.springframework.boot.web.servlet.ServletContextInitializerBeans.<init>(ServletContextInitializerBeans.java:79)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getServletContextInitializerBeans(EmbeddedWebApplicationContext.java:241)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.selfInitialize(EmbeddedWebApplicationContext.java:228)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.access$000(EmbeddedWebApplicationContext.java:89)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext$1.onStartup(EmbeddedWebApplicationContext.java:213)
at org.springframework.boot.context.embedded.tomcat.TomcatStarter.onStartup(TomcatStarter.java:55)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5178)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1419)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration$$EnhancerBySpringCGLIB$$e04a54a4]: Constructor threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'multipartConfigElement' defined in com.locision.system.cgc.SmartDustbinServiceApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.servlet.MultipartConfigElement]: Factory method 'multipartConfigElement' threw exception; nested exception is java.lang.RuntimeException: java.lang.NullPointerException
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:154)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:122)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:271)
... 34 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'multipartConfigElement' defined in com.locision.system.cgc.SmartDustbinServiceApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.servlet.MultipartConfigElement]: Factory method 'multipartConfigElement' threw exception; nested exception is java.lang.RuntimeException: java.lang.NullPointerException
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
at org.springframework.beans.factory.support.DefaultListableBeanFactory$DependencyObjectProvider.getIfAvailable(DefaultListableBeanFactory.java:1655)
at org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration.<init>(DispatcherServletAutoConfiguration.java:132)
at org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration$$EnhancerBySpringCGLIB$$e04a54a4.<init>(<generated>)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:142)
... 36 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.servlet.MultipartConfigElement]: Factory method 'multipartConfigElement' threw exception; nested exception is java.lang.RuntimeException: java.lang.NullPointerException
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
... 54 common frames omitted
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
at com.locision.system.cgc.utils.PathKit.detectWebRootPath(PathKit.java:69)
at com.locision.system.cgc.utils.PathKit.getWebRootPath(PathKit.java:51)
at com.locision.system.cgc.SmartDustbinServiceApplication.multipartConfigElement(SmartDustbinServiceApplication.java:24)
at com.locision.system.cgc.SmartDustbinServiceApplication$$EnhancerBySpringCGLIB$$52753fe2.CGLIB$multipartConfigElement$0(<generated>)
at com.locision.system.cgc.SmartDustbinServiceApplication$$EnhancerBySpringCGLIB$$52753fe2$$FastClassBySpringCGLIB$$19b23762.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:358)
at com.locision.system.cgc.SmartDustbinServiceApplication$$EnhancerBySpringCGLIB$$52753fe2.multipartConfigElement(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
... 55 common frames omitted
Caused by: java.lang.NullPointerException: null
at com.locision.system.cgc.utils.PathKit.detectWebRootPath(PathKit.java:66)
... 67 common frames omitted
运行PathKit.java时， PathKit.class.getResource（＆＃34; /＆＃34;），它总是返回null。为什么呢？