Question

我不明白如何使用@Autowired，对于我使用new的创建对象，但我需要替换为@Autowired。

private PupilServiceImpl pupilService = new PupilServiceImpl(); //need replace on @Autowired

spirng.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns="http://www.springframework.org/schema/beans"
        xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
    <context:component-scan base-package="controller"/>
    <context:annotation-config/>
    <bean id="pupilService" class="service.implement.PupilServiceImpl"/>
    <bean id="pupilDAO" class="dao.implement.PupilDAOImpl"/>
</beans>

控制器

@RestController
public class PupilController {

    @Autowired
    private PupilServiceImpl pupilService;

    public void setPupilService(PupilServiceImpl pupilService) {
        this.pupilService = pupilService;
    }
}

服务

public class PupilServiceImpl implements PupilService {
    @Autowired
    private PupilDAOImpl pupilDAO;

    public void setPupilDAO(PupilDAOImpl pupilDAO) {
        this.pupilDAO = pupilDAO;
    }
}

异常：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pupilController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private service.implement.PupilServiceImpl controller.PupilController.pupilService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [service.implement.PupilServiceImpl] 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)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1214)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:305)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:301)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:834)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:118)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:686)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:957)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:946)
    at controller.RunnerApplication.main(RunnerApplication.java:15)
    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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private service.implement.PupilServiceImpl controller.PupilController.pupilService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [service.implement.PupilServiceImpl] 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:571)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
    ... 21 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [service.implement.PupilServiceImpl] 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:1326)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1072)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:967)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:543)
    ... 23 common frames omitted

Answer 1

您必须注释所有要注入@Component注释或...

的类

@Component - 任何Spring管理组件的通用构造型
  @Repository - 持久层的构造型
  @Service - 服务层的构造型
  @Controller - 表示层的构造型（spring-mvc）

所以带注释的类可以用Spring注释@Autowired注释

@Aurowired错误创建bean

1 个答案: