通过@Autowired向service注入dao无法正常使用

Z时代
2024-01-10
分类：IT

controller代码

service代码

dao代码，侧栏可看结构

报错信息

具体如下：
DEBUG [localhost-startStop-1] - Failed to meta-introspect annotation interface org.springframework.beans.factory.annotation.Autowired: java.lang.NullPointerException
WARN [localhost-startStop-1] - Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userServiceImpl': Unsatisfied dependency expressed through field 'userdao'; nested exception isorg.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.fruitsalesplatform.dao.UserDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
DEBUG [localhost-startStop-1] - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@7fa50175: defining beans [org.springframework.context.support.PropertySourcesPlaceholderConfigurer#0,userDaoImpl,userServiceImpl,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.event.internalEventListenerProcessor,org.springframework.context.event.internalEventListenerFactory,testDaoImpl,testServiceImpl,dataSource,sessionFactory,transactionManager,txAdvice,org.springframework.aop.config.internalAutoProxyCreator,txPointcut,org.springframework.aop.support.DefaultBeanFactoryPointcutAdvisor#0]; root of factory hierarchy
DEBUG [localhost-startStop-1] - Retrieved dependent beans for bean 'sessionFactory': [userDaoImpl]
ERROR [localhost-startStop-1] - Context initialization failed
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userServiceImpl': Unsatisfied dependency expressed through field 'userdao'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.fruitsalesplatform.dao.UserDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:587) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:373) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1344) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:578) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:409) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:291) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:103) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4727) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5189) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:752) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:728) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1107) at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1841) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.fruitsalesplatform.dao.UserDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1509) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)

... 28 more

五月 20, 2018 4:29:15 上午 org.apache.catalina.core.StandardContext listenerStart
严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userServiceImpl': Unsatisfied dependency expressed through field 'userdao'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.fruitsalesplatform.dao.UserDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at java.lang.Thread.run(Unknown Source)

回答：

看这个信息，应该是spring没有扫描到dao层，你看一下配置文件配置的是否正确。

回答：

确认一下配置文件的扫描路径是否正确

回答：

配置出问题了。类前面都没有spring注入的标记

回答：

是mapper文件问题

回答：

首先spring会先注册扫描自身组件到bean容器，然后加载用户定义bean到容器在加载的同时为每个bean分配不同的beanID，当spring需要用到那个bean的时候会默认按照bean ID的方式寻找bean，确认容器中不存在某bean ID后抛出寻找不到某某某bean异常。从包扫描这个点切入便可解决问题。