java - 注入(inject) Autowiring 依赖项失败 - 无法 Autowiring 字段(Spring)

Question

我正在构建一个应用程序，通过 Snarl API 以及前端的 Springboot 连接到 Stardog 数据库。 snarlTemplate 的 Autowiring bean 工作正常，但我定义的任何组件都存在问题。我已经取出 ValidationDAO 的 Autowiring 并加载它。我查看了其他帖子也有同样的问题，但找不到解决方案。

首先，这是 DAO(我已将其注释为组件)...验证是在不同文件中定义的 POJO。
src/main/java/validation/ValidationDAO.java

@ComponentScan("com.complexible.stardog.ext.spring")
@Component
public class ValidationDAO {

    private static final Logger logger = LoggerFactory.getLogger(ValidationDAO.class);

    @Autowired
    public SnarlTemplate snarlTemplate;

    public List<Validation> validate() {

        // TODO: file input

        String query = "SELECT * WHERE { ?s ?p ?o }";

        logger.debug("DAO Query: " + query);
        List<Validation> results = snarlTemplate.query(query, new RowMapper<Validation>() {

            public Validation mapRow(BindingSet bindingSet) {
                Validation v = new Validation();

                // set results of query
                v.setSubject(bindingSet.getValue("s").stringValue());
                v.setPredicate(bindingSet.getValue("p").stringValue());
                v.setObject(bindingSet.getValue("o").stringValue());

                // set error message
                v.setError("No given description.");

                return v;
            }
        });

        return results;
    }

    public SnarlTemplate getSnarlTemplate() {
        return snarlTemplate;
    }

    public void setSnarlTemplate(SnarlTemplate snarlTemplate) {
        this.snarlTemplate = snarlTemplate;
    }

}

然后这是 HomeController:
src/main/java/validation/HomeController.java

@RestController
public class HomeController {

    private static final Logger logger = LoggerFactory.getLogger(HomeController.class);

    @Autowired
    public ValidationDAO validationDAO;

    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String home(Locale locale, Model model) {

        List<Validation> results = validationDAO.validate();
        logger.debug("Found " + results.size() + " errors in ontology.");
        model.addAttribute("results", results);
        return "home";

    }

    public ValidationDAO getValidationDAO() {
        return validationDAO;
    }

    public void setValidationDAO(ValidationDAO validationDAO) {
        this.validationDAO = validationDAO;
    }

}

根上下文:
src/main/webapp/WEB-INF/spring/root-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <context:component-scan base-package="src.main.java.validation"/>
     <context:annotation-config/>

    <bean name="dataSource" class="com.complexible.stardog.ext.spring.DataSourceFactoryBean">
        <property name="to" value="validationTest"/>
        <property name="username" value="admin"/>
        <property name="password" value="admin"/>
        <property name="url" value="snarl://localhost:5820"/>
    </bean>

    <bean name="template" class="com.complexible.stardog.ext.spring.SnarlTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>

</beans>

最后是完整的错误消息。

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'homeController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: public validation.ValidationDAO validation.HomeController.validationDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'validationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: public com.complexible.stardog.ext.spring.SnarlTemplate validation.ValidationDAO.snarlTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.complexible.stardog.ext.spring.SnarlTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1214) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:118) ~[spring-boot-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:766) [spring-boot-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.boot.SpringApplication.createAndRefreshContext(SpringApplication.java:361) [spring-boot-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) [spring-boot-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1191) [spring-boot-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1180) [spring-boot-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at validation.Application.main(Application.java:14) [main/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: public validation.ValidationDAO validation.HomeController.validationDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'validationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: public com.complexible.stardog.ext.spring.SnarlTemplate validation.ValidationDAO.snarlTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.complexible.stardog.ext.spring.SnarlTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:573) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    ... 17 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'validationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: public com.complexible.stardog.ext.spring.SnarlTemplate validation.ValidationDAO.snarlTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.complexible.stardog.ext.spring.SnarlTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1214) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1192) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1116) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:545) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    ... 19 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: public com.complexible.stardog.ext.spring.SnarlTemplate validation.ValidationDAO.snarlTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.complexible.stardog.ext.spring.SnarlTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:573) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    ... 30 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.complexible.stardog.ext.spring.SnarlTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1373) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1119) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:545) ~[spring-beans-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    ... 32 common frames omitted

Answer 1

ComponentScan 注释应该位于配置中，而不是位于组件类中。我真的不知道它是否有效，并且它包含一个您没有提到的软件包。

第二点:不要使用字段注入(inject)。 (http://olivergierke.de/2013/11/why-field-injection-is-evil/)

现在回到问题:我认为您在 xml 文件中的组件扫描是错误的，或者您的包有一些令人困惑的名称。但我很确定这是你的 maven/gradle 文件路径；)它不应该包含文件路径，而只包含包validation。

<context:component-scan base-package="validation"/><context:annotation-config/>