[英]spring-boot-starter-web @Autowired isn't working
我問了一個類似的問題，並認為它得到了回答。 然而，昨天它停止工作，所以我將再次詢問，但我修改了類。 我希望這是正確的協議....
我有一個spring-boot-starter-web，它在啟動時拋出一個空指針，因為其中一個類沒有被自動裝配。 這是我的設置：
package com.company.product
@Configuration
@ComponentScan
@EnableJpaRepositories
@EnableAutoConfiguration
public class OFAC {
public static void main(String[] args) {
ApplicationContext ofac = SpringApplication.run( OFAC.class, args );
}
}
在子包中我有：package com.company.product.configuration @Configuration @ComponentScan（）public class OFAConfiguration {
@Autowired
private ConfigurationSettings configurationSettings;
@Bean
public EmbeddedServletContainerFactory servletContainer() {
int port = 9000;
TomcatEmbeddedServletContainerFactory factory = new TomcatEmbeddedServletContainerFactory();
if ( configurationSettings.getServerPort()!= null ) {
port = Integer.parseInt( configurationSettings.getServerPort());
}
factory.setPort( port );
factory.setSessionTimeout( 30, TimeUnit.MINUTES );
factory.addErrorPages( new ErrorPage( HttpStatus.NOT_FOUND, "/notfound.html" ) );
return factory;
}
..}
@Autowired時，以下類為null，但我可以設置斷點並初始化它。 package com.company.product.configuration @Component @ConfigurationProperties（）public class ConfigurationSettings {
@Value("${ofac.appName}")
private String appName;
@Value("${ofac.appDescription}")
private String appDescription;
@Value("${ofac.serverPort}")
private String serverPort;
// getters and setters
..
}
這是拋出空指針的地方，因為ConfigurationSettings為null：package com.company.product.service @Component public class FileDownloadService {
@Autowired
private ConfigurationSettings configurationSettings;
private List<String> paths = new ArrayList<String>();
public FileDownloadService() {
paths.add( configurationSettings.getFileDownloadSdn() );
paths.add( configurationSettings.getFileDownloadAdd() );
paths.add( configurationSettings.getFilDownloadAlt() );
paths.add( configurationSettings.getFileDownloadXmlHeader() );
}
這是我的日志輸出：
:: Spring Boot :: (v1.0.0.RC4)
2014-03-14 17:59:16.975 INFO 41410 --- [ main] com.company.product.OFAC : Starting OFAC on Edelweiss.local with PID 41410 (/Users/David/projects/cnet/OFAC/out/production/OFAC started by...)
2014-03-14 17:59:16.981 DEBUG 41410 --- [ main] o.s.boot.SpringApplication : Loading source class com.company.product.OFAC
2014-03-14 17:59:17.517 INFO 41410 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@64de5c64: startup date [Fri Mar 14 17:59:17 MDT 2014]; root of context hierarchy
2014-03-14 17:59:17.522 DEBUG 41410 --- [ main] ationConfigEmbeddedWebApplicationContext : Bean factory for org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@64de5c64: org.springframework.beans.factory.support.DefaultListableBeanFactory@600f2cb8: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,OFAC]; root of factory hierarchy
2014-03-14 17:59:20.249 DEBUG 41410 --- [ main] ationConfigEmbeddedWebApplicationContext : Using MessageSource [org.springframework.context.support.ReloadableResourceBundleMessageSource: basenames=[classpath:messages/messages,classpath:messages/validation]]
2014-03-14 17:59:20.249 DEBUG 41410 --- [ main] ationConfigEmbeddedWebApplicationContext : Using ApplicationEventMulticaster [org.springframework.context.event.SimpleApplicationEventMulticaster@4e5197fd]
2014-03-14 17:59:25.590 DEBUG 41410 --- [ main] .t.TomcatEmbeddedServletContainerFactory : Code archive: /..gvm/gradle/1.10/bin/caches/modules-2/files-2.1/org.springframework.boot/spring-boot/1.0.0.RC4/b8934d1dcdfd6f454ad86ea7372fd8a6dd2f6e61/spring-boot-1.0.0.RC4.jar
2014-03-14 17:59:25.591 DEBUG 41410 --- [ main] .t.TomcatEmbeddedServletContainerFactory : Code archive: /..gvm/gradle/1.10/bin/caches/modules-2/files-2.1/org.springframework.boot/spring-boot/1.0.0.RC4/b8934d1dcdfd6f454ad86ea7372fd8a6dd2f6e61/spring-boot-1.0.0.RC4.jar
2014-03-14 17:59:25.591 DEBUG 41410 --- [ main] .t.TomcatEmbeddedServletContainerFactory : Document root: /Users/me/projects/cnet/OFAC/src/main/webapp
2014-03-14 17:59:25.642 INFO 41410 --- [ main] .t.TomcatEmbeddedServletContainerFactory : Server initialized with port: 9001
2014-03-14 17:59:26.156 INFO 41410 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat
2014-03-14 17:59:26.157 INFO 41410 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/7.0.52
2014-03-14 17:59:26.463 INFO 41410 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2014-03-14 17:59:26.464 INFO 41410 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 8954 ms
2014-03-14 17:59:27.348 INFO 41410 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2014-03-14 17:59:27.353 INFO 41410 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2014-03-14 17:59:28.064 INFO 41410 --- [ost-startStop-1] o.a.catalina.util.SessionIdGenerator : Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [203] milliseconds.
2014-03-14 17:59:28.232 INFO 41410 --- [ main] o.s.j.d.e.EmbeddedDatabaseFactory : Creating embedded database 'ofac'
2014-03-14 17:59:28.509 INFO 41410 --- [ main] o.s.j.d.init.ResourceDatabasePopulator : Executing SQL script from class path resource [h2.sql]
2014-03-14 17:59:28.526 INFO 41410 --- [ main] o.s.j.d.init.ResourceDatabasePopulator : Done executing SQL script from class path resource [h2.sql] in 17 ms.
2014-03-14 17:59:28.763 INFO 41410 --- [ main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default'
2014-03-14 17:59:28.814 INFO 41410 --- [ main] o.hibernate.jpa.internal.util.LogHelper : HHH000204: Processing PersistenceUnitInfo [
name: default
...]
2014-03-14 17:59:29.117 INFO 41410 --- [ main] org.hibernate.Version : HHH000412: Hibernate Core {4.3.1.Final}
2014-03-14 17:59:29.120 INFO 41410 --- [ main] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found
2014-03-14 17:59:29.123 INFO 41410 --- [ main] org.hibernate.cfg.Environment : HHH000021: Bytecode provider name : javassist
2014-03-14 17:59:29.545 INFO 41410 --- [ main] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {4.0.4.Final}
2014-03-14 17:59:29.684 INFO 41410 --- [ main] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.H2Dialect
2014-03-14 17:59:29.846 INFO 41410 --- [ main] o.h.h.i.ast.ASTQueryTranslatorFactory : HHH000397: Using ASTQueryTranslatorFactory
2014-03-14 17:59:30.010 INFO 41410 --- [ main] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000228: Running hbm2ddl schema update
2014-03-14 17:59:30.011 INFO 41410 --- [ main] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000102: Fetching database metadata
2014-03-14 17:59:30.014 INFO 41410 --- [ main] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000396: Updating schema
2014-03-14 17:59:30.015 INFO 41410 --- [ main] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000232: Schema update complete
2014-03-14 17:59:39.493 INFO 41410 --- [ main] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2014-03-14 17:59:39.558 INFO 41410 --- [ main] o.apache.catalina.core.StandardService : Stopping service Tomcat
=========================
AUTO-CONFIGURATION REPORT
=========================
Positive matches:
-----------------
PropertyPlaceholderAutoConfiguration#propertySourcesPlaceholderConfigurer
- @ConditionalOnMissingBean (types: org.springframework.context.support.PropertySourcesPlaceholderConfigurer; SearchStrategy: current) found no beans (OnBeanCondition)
AopAutoConfiguration
- @ConditionalOnClass classes found: org.springframework.context.annotation.EnableAspectJAutoProxy,org.aspectj.lang.annotation.Aspect,org.aspectj.lang.reflect.Advice (OnClassCondition)
- SpEL expression on org.springframework.boot.autoconfigure.aop.AopAutoConfiguration: ${spring.aop.auto:true} (OnExpressionCondition)
AopAutoConfiguration.JdkDynamicAutoProxyConfiguration
- SpEL expression on org.springframework.boot.autoconfigure.aop.AopAutoConfiguration$JdkDynamicAutoProxyConfiguration: !${spring.aop.proxyTargetClass:false} (OnExpressionCondition)
JpaRepositoriesAutoConfiguration
- @ConditionalOnClass classes found: org.springframework.data.jpa.repository.JpaRepository (OnClassCondition)
- @ConditionalOnBean (types: javax.sql.DataSource; SearchStrategy: all) found the following [dataSource] @ConditionalOnMissingBean (types: org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean; SearchStrategy: all) found no beans (OnBeanCondition)
JpaRepositoriesAutoConfiguration.JpaWebConfiguration
- found web application StandardServletEnvironment (OnWebApplicationCondition)
- @ConditionalOnMissingBean (types: org.springframework.data.web.PageableHandlerMethodArgumentResolver; SearchStrategy: all) found no beans (OnBeanCondition)
DataSourceAutoConfiguration
- @ConditionalOnClass classes found: org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType (OnClassCondition)
DataSourceAutoConfiguration.JdbcTemplateConfiguration
- existing auto database detected (DataSourceAutoConfiguration.DatabaseCondition)
DataSourceAutoConfiguration.JdbcTemplateConfiguration#jdbcTemplate
- @ConditionalOnMissingBean (types: org.springframework.jdbc.core.JdbcOperations; SearchStrategy: all) found no beans (OnBeanCondition)
DataSourceAutoConfiguration.JdbcTemplateConfiguration#namedParameterJdbcTemplate
- @ConditionalOnMissingBean (types: org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations; SearchStrategy: all) found no beans (OnBeanCondition)
DataSourceTransactionManagerAutoConfiguration
- @ConditionalOnClass classes found: org.springframework.jdbc.core.JdbcTemplate,org.springframework.transaction.PlatformTransactionManager (OnClassCondition)
JmxAutoConfiguration
- @ConditionalOnClass classes found: org.springframework.jmx.export.MBeanExporter (OnClassCondition)
- SpEL expression on org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration: ${spring.jmx.enabled:true} (OnExpressionCondition)
- @ConditionalOnMissingBean (types: org.springframework.jmx.export.MBeanExporter; SearchStrategy: all) found no beans (OnBeanCondition)
HibernateJpaAutoConfiguration
- found HibernateEntityManager class (HibernateJpaAutoConfiguration.HibernateEntityManagerCondition)
- @ConditionalOnClass classes found: org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean,org.springframework.transaction.annotation.EnableTransactionManagement,javax.persistence.EntityManager (OnClassCondition)
JpaBaseConfiguration.JpaWebConfiguration
- found web application StandardServletEnvironment (OnWebApplicationCondition)
- SpEL expression on org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration$JpaWebConfiguration: ${spring.jpa.openInView:${spring.jpa.open_in_view:true}} (OnExpressionCondition)
- @ConditionalOnMissingBean (types: org.springframework.orm.jpa.support.OpenEntityManagerInViewInterceptor,org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter; SearchStrategy: all) found no beans (OnBeanCondition)
ThymeleafAutoConfiguration
- @ConditionalOnClass classes found: org.thymeleaf.spring4.SpringTemplateEngine (OnClassCondition)
ThymeleafAutoConfiguration.DefaultTemplateResolverConfiguration
- @ConditionalOnMissingBean (names: defaultTemplateResolver; SearchStrategy: all) found no beans (OnBeanCondition)
ThymeleafAutoConfiguration.ThymeleafDefaultConfiguration
- @ConditionalOnMissingBean (types: org.thymeleaf.spring4.SpringTemplateEngine; SearchStrategy: all) found no beans (OnBeanCondition)
ThymeleafAutoConfiguration.ThymeleafViewResolverConfiguration
- @ConditionalOnClass classes found: javax.servlet.Servlet (OnClassCondition)
com.edelweissco.ofac
ThymeleafAutoConfiguration.ThymeleafViewResolverConfiguration#thymeleafViewResolver
- @ConditionalOnMissingBean (names: thymeleafViewResolver; SearchStrategy: all) found no beans (OnBeanCondition)
DispatcherServletAutoConfiguration
- found web application StandardServletEnvironment (OnWebApplicationCondition)
- @ConditionalOnClass classes found: org.springframework.web.servlet.DispatcherServlet (OnClassCondition)
DispatcherServletAutoConfiguration.DispatcherServletConfiguration
- no DispatcherServlet found (DispatcherServletAutoConfiguration.DefaultDispatcherServletCondition)
- @ConditionalOnClass classes found: javax.servlet.ServletRegistration (OnClassCondition)
EmbeddedServletContainerAutoConfiguration
- found web application StandardServletEnvironment (OnWebApplicationCondition)
HttpMessageConvertersAutoConfiguration
- @ConditionalOnClass classes found: org.springframework.http.converter.HttpMessageConverter (OnClassCondition)
HttpMessageConvertersAutoConfiguration#messageConverters
- @ConditionalOnMissingBean (types: org.springframework.boot.autoconfigure.web.HttpMessageConverters; SearchStrategy: all) found no beans (OnBeanCondition)
HttpMessageConvertersAutoConfiguration.ObjectMappers
- @ConditionalOnClass classes found: com.fasterxml.jackson.databind.ObjectMapper (OnClassCondition)
HttpMessageConvertersAutoConfiguration.ObjectMappers#jacksonObjectMapper
- @ConditionalOnMissingBean (types: com.fasterxml.jackson.databind.ObjectMapper; SearchStrategy: all) found no beans (OnBeanCondition)
HttpMessageConvertersAutoConfiguration.ObjectMappers#mappingJackson2HttpMessageConverter
- @ConditionalOnMissingBean (types: org.springframework.http.converter.json.MappingJackson2HttpMessageConverter; SearchStrategy: all) found no beans (OnBeanCondition)
ServerPropertiesAutoConfiguration
- found web application StandardServletEnvironment (OnWebApplicationCondition)
ServerPropertiesAutoConfiguration#serverProperties
- @ConditionalOnMissingBean (types: org.springframework.boot.autoconfigure.web.ServerProperties; SearchStrategy: current) found no beans (OnBeanCondition)
WebMvcAutoConfiguration
- found web application StandardServletEnvironment (OnWebApplicationCondition)
- @ConditionalOnClass classes found: javax.servlet.Servlet,org.springframework.web.servlet.DispatcherServlet,org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter (OnClassCondition)
- @ConditionalOnMissingBean (types: org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport; SearchStrategy: all) found no beans (OnBeanCondition)
WebMvcAutoConfiguration#hiddenHttpMethodFilter
- @ConditionalOnMissingBean (types: org.springframework.web.filter.HiddenHttpMethodFilter; SearchStrategy: all) found no beans (OnBeanCondition)
WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter#defaultViewResolver
- @ConditionalOnMissingBean (types: org.springframework.web.servlet.view.InternalResourceViewResolver; SearchStrategy: all) found no beans (OnBeanCondition)
WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter#requestContextListener
- @ConditionalOnMissingBean (types: org.springframework.web.context.request.RequestContextListener; SearchStrategy: all) found no beans (OnBeanCondition)
Negative matches:
-----------------
MessageSourceAutoConfiguration
- @ConditionalOnMissingBean (types: org.springframework.context.MessageSource; SearchStrategy: all) found the following [messageSource] (OnBeanCondition)
RabbitAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.amqp.rabbit.core.RabbitTemplate,com.rabbitmq.client.Channel (OnClassCondition)
AopAutoConfiguration.CglibAutoProxyConfiguration
- SpEL expression on org.springframework.boot.autoconfigure.aop.AopAutoConfiguration$CglibAutoProxyConfiguration: ${spring.aop.proxyTargetClass:false} (OnExpressionCondition)
BatchAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.batch.core.launch.JobLauncher (OnClassCondition)
MongoRepositoriesAutoConfiguration
- required @ConditionalOnClass classes not found: com.mongodb.Mongo,org.springframework.data.mongodb.repository.MongoRepository (OnClassCondition)
MongoTemplateAutoConfiguration
- required @ConditionalOnClass classes not found: com.mongodb.Mongo,org.springframework.data.mongodb.core.MongoTemplate (OnClassCondition)
DataSourceAutoConfiguration.DbcpConfiguration
- Tomcat DataSource (DataSourceAutoConfiguration.BasicDatabaseCondition)
DataSourceAutoConfiguration.EmbeddedConfiguration
- existing non-embedded database detected (DataSourceAutoConfiguration.EmbeddedDatabaseCondition)
DataSourceAutoConfiguration.TomcatConfiguration
- found database driver org.h2.Driver (DataSourceAutoConfiguration.TomcatDatabaseCondition)
- @ConditionalOnMissingBean (types: javax.sql.DataSource; SearchStrategy: all) found the following [dataSource] (OnBeanCondition)
DataSourceTransactionManagerAutoConfiguration#transactionManager
- @ConditionalOnMissingBean (names: transactionManager; SearchStrategy: all) found the following [transactionManager] (OnBeanCondition)
DataSourceTransactionManagerAutoConfiguration.TransactionManagementConfiguration
- required @ConditionalOnMissing classes found: org.springframework.transaction.annotation.AbstractTransactionManagementConfiguration (OnClassCondition)
JmsTemplateAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.jms.core.JmsTemplate,javax.jms.ConnectionFactory (OnClassCondition)
DeviceResolverAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.mobile.device.DeviceResolverHandlerInterceptor,org.springframework.mobile.device.DeviceHandlerMethodArgumentResolver (OnClassCondition)
MongoAutoConfiguration
- required @ConditionalOnClass classes not found: com.mongodb.Mongo (OnClassCondition)
JpaBaseConfiguration#entityManagerFactory
- @ConditionalOnMissingBean (names: entityManagerFactory; SearchStrategy: all) found the following [entityManagerFactory] (OnBeanCondition)
JpaBaseConfiguration#jpaVendorAdapter
- @ConditionalOnMissingBean (types: org.springframework.orm.jpa.JpaVendorAdapter; SearchStrategy: all) found the following [jpaVendorAdapter] (OnBeanCondition)
JpaBaseConfiguration#transactionManager
- @ConditionalOnMissingBean (types: org.springframework.transaction.PlatformTransactionManager; SearchStrategy: all) found the following [transactionManager] (OnBeanCondition)
ReactorAutoConfiguration
- required @ConditionalOnClass classes not found: reactor.spring.context.config.EnableReactor (OnClassCondition)
RedisAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.data.redis.connection.lettuce.LettuceConnection,org.springframework.data.redis.core.RedisOperations,com.lambdaworks.redis.RedisClient (OnClassCondition)
SecurityAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.security.authentication.AuthenticationManager (OnClassCondition)
ThymeleafAutoConfiguration.ThymeleafSecurityDialectConfiguration
- required @ConditionalOnClass classes not found: org.thymeleaf.extras.springsecurity3.dialect.SpringSecurityDialect (OnClassCondition)
ThymeleafAutoConfiguration.ThymeleafWebLayoutConfiguration
- required @ConditionalOnClass classes not found: nz.net.ultraq.thymeleaf.LayoutDialect (OnClassCondition)
EmbeddedServletContainerAutoConfiguration.EmbeddedJetty
- required @ConditionalOnClass classes not found: org.eclipse.jetty.server.Server,org.eclipse.jetty.util.Loader (OnClassCondition)
EmbeddedServletContainerAutoConfiguration.EmbeddedTomcat
- @ConditionalOnClass classes found: javax.servlet.Servlet,org.apache.catalina.startup.Tomcat (OnClassCondition)
- @ConditionalOnMissingBean (types: org.springframework.boot.context.embedded.EmbeddedServletContainerFactory; SearchStrategy: current) found the following [servletContainer] (OnBeanCondition)
MultipartAutoConfiguration
- @ConditionalOnClass classes found: javax.servlet.Servlet,org.springframework.web.multipart.support.StandardServletMultipartResolver (OnClassCondition)
- @ConditionalOnBean (types: javax.servlet.MultipartConfigElement; SearchStrategy: all) found no beans (OnBeanCondition)
WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter#beanNameViewResolver
- @ConditionalOnBean (types: org.springframework.web.servlet.View; SearchStrategy: all) found no beans (OnBeanCondition)
WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter#viewResolver
- @ConditionalOnBean (types: org.springframework.web.servlet.View; SearchStrategy: all) found no beans (OnBeanCondition)
WebSocketAutoConfiguration
- required @ConditionalOnClass classes not found: org.springframework.web.socket.WebSocketHandler (OnClassCondition)
這是堆棧跟蹤，只是標准的NullPointerException。 在此調用之前，ConfigurationSetting已經實例化（根據調試器）。 但是，在創建FileDownloadService時，ConfigurationSetting為null。
引起：org.springframework.beans.factory.BeanCreationException：創建文件[.cnet / OFAC / out / production / OFAC / com / company / product / service / FileDownloadService.class]中定義名為'fileDownloadService'的bean時出錯：實例化豆失敗; 嵌套異常是org.springframework.beans.BeanInstantiationException：無法實例化bean類[com.company.product.service.FileDownloadService]：構造函數拋出異常; 嵌套異常是org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean（AbstractAutowireCapableBeanFactory.java:1076）中的java.lang.NullPointerException，位於org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance（AbstractAutowireCapableBeanFactory.java:1021）在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:504）在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:475）在org.springframework.beans.factory .support.AbstractBeanFactory $ 1.getObject（AbstractBeanFactory.java:304）org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:228）org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（ AbstractBeanFactory.java:300）at org.springframework.beans.factory.support.Abstr actBeanFactory.getBean（AbstractBeanFactory.java:195）org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates（DefaultListableBeanFactory.java:1014）org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency（DefaultListableBeanFactory.java： 957）org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency（DefaultListableBeanFactory.java:855）org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor $ AutowiredFieldElement.inject（AutowiredAnnotationBeanPostProcessor.java：480）... 18更多由以下原因引起：org.springframework.beans.BeanInstantiationException：無法實例化bean類[com.company.product.service.FileDownloadService]：構造函數拋出異常; 在org.springframework的org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate（SimpleInstantiationStrategy.java:89）的org.springframework.beans.BeanUtils.instantiateClass（BeanUtils.java:164）中的嵌套異常是java.lang.NullPointerException .beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean（AbstractAutowireCapableBeanFactory.java:1069）... 29更多引起：com.company.product.service.FileDownloadService的java.lang.NullPointerException。（FileDownloadService.java：29）at sun at.reflect.NativeConstructorAccessorImpl.newInstance0（Native Method）at sun.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:57）at sun.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:45）at java.lang.reflect.Constructor.newInstance （Constructor.java:526）org.springframework.beans.BeanUtils.instantiateClass（BeanUtils.java:148）... 31更多
現在我發誓在上周一些非常好的StackOverflow幫助之后，這一切都在發揮作用。 但是，我現在無法運行我的應用程序，因為啟動時出現空指針。
對不起，本來應該看到這個，但堆棧跟蹤顯而易見：它不是一個彈簧自動裝配錯誤，因為Spring永遠不會看到你的FileDownloadService的實例 - 你在它的構造函數中使用了一個未初始化的字段。 如果要在初始值設定項中引用@Autowired字段，請使用@PostConstruct而不是構造函數。
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