自动装配依赖项注入失败，无法自动装配字段

Question

我知道这个问题被问了很多，我冒着双重（或三重或四重）主题的风险，但建议的解决方案似乎对我不起作用。

我遇到了可怕的无法自动装配错误。第一次从头开始建立一个完整的 Spring 项目，所以我真的不知道问题出在哪里。

这是我当前的设置：项目回购：

package be.italent.repo;

import be.italent.model.Project;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface ProjectRepo extends JpaRepository<Project, Integer> {

}

项目服务：

package be.italent.services;

import be.italent.model.Project;
import be.italent.repo.ProjectRepo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class ProjectService {

    @Autowired
    private ProjectRepo projectRepo;

    public List<Project> getAllProjects() {
        return projectRepo.findAll();
    }
}

ProjectRestController:

package be.italent.controllers;

import java.util.ArrayList;
import be.italent.services.ProjectService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import be.italent.model.Project;

@RestController
@RequestMapping("/projects")
public class ProjectRestController {

    @Autowired
    private ProjectService projectService;

    @RequestMapping(method = RequestMethod.GET, produces="application/json")
    public ArrayList<Project> getProjects(){
        ArrayList<Project> c = (ArrayList<Project>) projectService.getAllProjects();

        return c;
    }
}

spring-mvc.xml

...
<context:component-scan base-package="be.italent"></context:component-scan>
...

错误：

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'projectRestController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private be.italent.services.ProjectService be.italent.controllers.ProjectRestController.projectService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'projectService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private be.italent.repo.ProjectRepo be.italent.services.ProjectService.projectRepo; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [be.italent.repo.ProjectRepo] 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:292) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475) at org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:304) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5068) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5584) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1572) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1562) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private be.italent.services.ProjectService be.italent.controllers.ProjectRestController.projectService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'projectService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private be.italent.repo.ProjectRepo be.italent.services.ProjectService.projectRepo; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [be.italent.repo.ProjectRepo] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289) ... 22 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'projectService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private be.italent.repo.ProjectRepo be.italent.services.ProjectService.projectRepo; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [be.italent.repo.ProjectRepo] 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:292) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475) at org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:304) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195) at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1014) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:957) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480) ... 24 more Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private be.italent.repo.ProjectRepo be.italent.services.ProjectService.projectRepo; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [be.italent.repo.ProjectRepo] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289) ... 35 more Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [be.italent.repo.ProjectRepo] 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:1100) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480) ... 37 more

有什么帮助吗？谢谢！

解决方案

将此添加到我的 spring-mvc.xml:

<beans
...
jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">

...

<jpa:repositories base-package="be.italent.repo" entity-manager-factory-ref="emf"/>

Answer 1

当初始化应用程序上下文时出现问题时，Spring 通常会给出这些长堆栈跟踪。通常你可以通过查看堆栈跟踪的底部找出最终原因。

在您的情况下，您会在底部看到此错误消息：

org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [be.italent.repo.ProjectRepo] found

这意味着 Spring 找不到类型为 ProjectRepo 的 bean。

你的ProjectRepo版本库接口在包be.italent.repo里，是be.italent的子包，是组件扫描的，所以问题不在错包。

您是否忘记启用 Spring Data JPA？

当您使用 XML 配置时（就像您现在所做的那样），您的配置文件中必须有一个 repositories XML 标记：

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

    <!-- Tell Spring Data JPA where your repository interfaces are -->
    <jpa:repositories base-package="be.italent.repo" />

    <!-- ... -->
</beans>

当你使用 JavaConfig 时，你可以通过注解来完成：

@Configuration
@EnableJpaRepositories("be.italent.repo")
public class MySpringConfiguration {
    // ...
}

Answer 2

问题出在 ProjectRestController.java 您已将 @Autowired 用于 ProjectService 1)

删除@Autowired 注释。
从 projectService.
在 spring.xml

ProjectService

现在运行您的申请。它对我有用。

自动装配依赖项注入失败，无法自动装配字段

Injection of autowired dependencies failed, Could not autowire field

java

spring

autowired