SSH配置bean注入及获取的方法

原创已于 2022-01-24 00:59:06 修改 · 1.2k 阅读

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#spring #bean #注入

于 2019-08-05 16:23:04 首次发布

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本文详细解析了Spring框架中因依赖注入类型不匹配导致的启动错误，阐述了正确的配置方式和解决策略，强调了面向接口编程的重要性。

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启动报错：Error creating bean with name ‘userServiceImpl’ defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'com.sun.proxy. $P r o x y 10 i m p l e m e n t i n g d e m o . s s h . d a o . U s e r s D a o, o r g . s p r i n g f r a m e w o r k . a o p . S p r i n g P r o x y, o r g . s p r i n g f r a m e w o r k . a o p . f r a m e w o r k . A d v i s e d^{'} t o r e q u i r e d t y p e^{'} d e m o . s s h . d a o I m p l . U s e r s D a o I m p l^{'} f o r p r o p e r t y^{'} d a o^{'}; n e s t e d e x c e p t i o n i s j a v a . l a n g . I l l e g a l S t a t e E x c e p t i o n : C a n n o t c o n v e r t v a l u e o f t y p e [c o m . s u n . p r o x y .$ Proxy10 implementing demo.ssh.dao.UsersDao,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [demo.ssh.daoImpl.UsersDaoImpl] for property ‘dao’: no matching editors or conversion strategy found

完整报错代码：

八月 05, 2019 4:14:45 下午 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.BeanCreationException: Error creating bean with name 'userServiceImpl' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'com.sun.proxy.$Proxy10 implementing demo.ssh.dao.UsersDao,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised' to required type 'demo.ssh.daoImpl.UsersDaoImpl' for property 'dao'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy10 implementing demo.ssh.dao.UsersDao,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [demo.ssh.daoImpl.UsersDaoImpl] for property 'dao': no matching editors or conversion strategy found
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:305)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:301)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:835)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:446)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:328)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4579)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5041)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:742)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:718)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:703)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1142)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1876)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112)
	at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1054)
	at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:428)
	at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1586)
	at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:308)
	at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
	at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:424)
	at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:367)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:966)
	at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:839)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1427)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1417)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134)
	at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:943)
	at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:258)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:770)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:682)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:353)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:493)
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'com.sun.proxy.$Proxy10 implementing demo.ssh.dao.UsersDao,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised' to required type 'demo.ssh.daoImpl.UsersDaoImpl' for property 'dao'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy10 implementing demo.ssh.dao.UsersDao,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [demo.ssh.daoImpl.UsersDaoImpl] for property 'dao': no matching editors or conversion strategy found
	at org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:591)
	at org.springframework.beans.AbstractNestablePropertyAccessor.convertForProperty(AbstractNestablePropertyAccessor.java:603)
	at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:204)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1527)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1486)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1226)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
	... 52 more
Caused by: java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy10 implementing demo.ssh.dao.UsersDao,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [demo.ssh.daoImpl.UsersDaoImpl] for property 'dao': no matching editors or conversion strategy found
	at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:302)
	at org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:576)
	... 58 more

原因：很明显，配置文件生成bean错误，是什么原因呢？原来是获取类的时候出错。Spring是面向接口编程，所以不能用实现类来得到bean，而应该用接口得到bean对象。

applicationContext配置:

<bean id="usersDaoImpl" class="demo.ssh.daoImpl.UsersDaoImpl">
		<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
<bean id="userServiceImpl" class="demo.ssh.serviceImpl.UserServiceImpl">
		<property name="dao" ref="usersDaoImpl"></property>
</bean>

获取bean:

public class UserServiceImpl implements UserService{  
    //用接口，不能用实现类
	private UsersDao dao; 
    public void setDao(UsersDao dao) {
		this.dao = dao;
	}
}