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如何理解@Resource注入失败问题，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
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项目结构
front和client是两个不同的服务，front依赖client项目，需要在front中注入client的类
声明类：
import com.bluewhale.infra.client.IRestClient;
... ...
@Component("defaultWebServiceRequestHandler")
public class DefaultWebServiceRequestHandler implements BaseHandler {
protected Logger logger = LoggerFactory.getLogger(this.getClass());
@Resource(name = "seckillClient")
private IRestClient seckillClient;
@Resource(name = "objectMapper")
protected ObjectMapper objectMapper;
@Resource(name = "restMapping")
public Map restMapping;
... ...
} 注解类：
import org.springframework.stereotype.Component;
import com.bluewhale.infra.client.IRestClient;
import com.bluewhale.infra.client.impl.BaseRestClient;
@Component("seckillClient")
public class SeckillClient extends BaseRestClient implements IRestClient {
@Override
protected String getServerUrl() {
return "http://etrade-trans-web/json/";
}
}seckillClent实现了IRestClient接口，在DefaultWebServiceRequestHandler 中注入IRestClient，通过@Resource注解找到对应的类。
但在启动front服务器报错
从报错日志可以看出是因为找不到名为“seckillClient”的依赖，注入失败。
从代码中来看，完全可以确定所有配置正常，注解正常
2019-08-19 11:00:59.105 INFO 7376 --- [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@31c7528f: startup date [Mon Aug 19 11:00:59 CST 2019]; root of context hierarchy 2019-08-19 11:00:59.294 INFO 7376 --- [ main] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring 2019-08-19 11:00:59.326 INFO 7376 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'configurationPropertiesRebinderAutoConfiguration' of type [org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration$$EnhancerBySpringCGLIB$$ddfb45d6] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) . ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.5.9.RELEASE) 2019-08-19 11:00:59.778 INFO 7376 --- [ main] c.c.c.ConfigServicePropertySourceLocator : Fetching config from server at: http://localhost:8888 2019-08-19 11:01:00.856 WARN 7376 --- [ main] c.c.c.ConfigServicePropertySourceLocator : Could not locate PropertySource: I/O error on GET request for "http://localhost:8888/bluewhale-seckill-front/default": Connection refused: connect; nested exception is java.net.ConnectException: Connection refused: connect 2019-08-19 11:01:00.856 INFO 7376 --- [ main] bluewhale.front.FrontApplication : No active profile set, falling back to default profiles: default 2019-08-19 11:01:00.903 INFO 7376 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5e4fa1da: startup date [Mon Aug 19 11:01:00 CST 2019]; parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@31c7528f 2019-08-19 11:01:01.825 INFO 7376 --- [ main] o.s.cloud.context.scope.GenericScope : BeanFactory id=34349be5-556c-35e3-8c99-3121c02e2e06 2019-08-19 11:01:01.840 INFO 7376 --- [ main] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring 2019-08-19 11:01:01.950 INFO 7376 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.cloud.netflix.metrics.MetricsInterceptorConfiguration$MetricsRestTemplateConfiguration' of type [org.springframework.cloud.netflix.metrics.MetricsInterceptorConfiguration$MetricsRestTemplateConfiguration$$EnhancerBySpringCGLIB$$f40de91a] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2019-08-19 11:01:02.013 INFO 7376 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration' of type [org.springframework.cloud.autoconfigure.ConfigurationPropertiesRebinderAutoConfiguration$$EnhancerBySpringCGLIB$$ddfb45d6] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2019-08-19 11:01:02.231 INFO 7376 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 11002 (http) 2019-08-19 11:01:02.247 INFO 7376 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2019-08-19 11:01:02.247 INFO 7376 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.23 2019-08-19 11:01:02.372 INFO 7376 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2019-08-19 11:01:02.372 INFO 7376 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1469 ms 2019-08-19 11:01:02.559 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'metricsFilter' to: [/*] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'webRequestLoggingFilter' to: [/*] 2019-08-19 11:01:02.575 INFO 7376 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'applicationContextIdFilter' to: [/*] 2019-08-19 11:01:02.685 WARN 7376 --- [ main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '/front': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'frontExecuter': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'frontProcessFactory': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'frontProcessConfig': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'logoutProcess': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'frontHandlerConfig': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultWebServiceRequestHandler': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'seckillClient' available 2019-08-19 11:01:02.685 INFO 7376 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat] 2019-08-19 11:01:02.700 INFO 7376 --- [ main] utoConfigurationReportLoggingInitializer : Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled. 2019-08-19 11:01:02.794 ERROR 7376 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter : *************************** APPLICATION FAILED TO START *************************** Description: A component required a bean named 'seckillClient' that could not be found. Action: Consider defining a bean named 'seckillClient' in your configuration.
经过排查及网上查询发现问题所在
因为项目有做业务分离，所以在启动front服务器，加载主程序时SpringBoot会对依赖包进行扫描，因此需要在主程序入口指定扫描的位置，否则有的地方可能会注入失败。
所以需要在front的Application中指定扫描的包
package bluewhale.front;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.context.annotation.ComponentScan;
@ComponentScan(basePackages = { "com.bluewhale.infra", "etrade" })
@EnableDiscoveryClient
@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })
public class FrontApplication {
public static void main(String[] args) throws Exception {
SpringApplication.run(FrontApplication.class, args);
}
}如果你的其他包层次结构位于使用@SpringBootApplication标注主应用程序下方，则隐式组件扫描将自动涵盖。也就是说，不要明确标注@ComponentScan，Spring Boot会自动搜索当前应用主入口目录及其下方子目录。
如果其他包中的bean /组件不在当前主包路径下面，，则应手动使用@ComponentScan 添加
如果使用了@ComponentScan ，那么Spring Boot就全部依赖你的定义，如果定义出错，会出现autowired时出错，报a bean of type that could not be found错误
看完上述内容，你们掌握如何理解@Resource注入失败问题的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注创新互联行业资讯频道，感谢各位的阅读！