org.springframework.beans.factory.UnsatisfiedDependencyException
org.springframework.beans.factory.BeanNotOfRequiredTypeException
异常
1)问题描述:
在进行ssm框架整合的时候,在进行相关的测试代码以及配置文件写完以后,tomcat服务器启动以后,就报了这个异常
org.springframework.beans.factory.BeanNotOfRequiredTypeException
,
这个是springAOP基于注解的配置时,发生了动态代理的异常,找不到指定的动态代理,属于代理注入的异常。
(2)错误显示:
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userService'; nested exception is org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'userServiceImpl' is expected to be of type 'cn.demo.service.impl.UserServiceImpl' but was actually of type 'com.sun.proxy.$Proxy20'
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$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:1348)
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.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:672)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:638)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:686)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:554)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:499)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1144)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1091)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:773)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:133)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'userServiceImpl' is expected to be of type 'cn.demo.service.impl.UserServiceImpl' but was actually of type 'com.sun.proxy.$Proxy20'
at org.springframework.beans.factory.support.DefaultListableBeanFactory.checkBeanNotOfRequiredType(DefaultListableBeanFactory.java:1527)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.checkBeanNotOfRequiredType(DefaultListableBeanFactory.java:1534)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1505)
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$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
... 39 more
(3)解决方案:
观察错误的日志,特别是关注于Caused by里面的内容,
Caused by: org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'userServiceImpl' is expected to be of type 'cn.demo.service.impl.UserServiceImpl' but was actually of type 'com.sun.proxy.$Proxy20'
由这个可以知道,spring的AOP注解配置时动态代理的异常,实现类UserServiceImpl不能使用jdk的动态代理注入,jdk的动态代理不支持类的注入,只支持接口的注入。如果不想使用jdk的接口动态代理,想要使用类的代理,那么就使用cglib的代理,需要引用cglib的依赖。
所以,在知道原因之后,我们就可以这样做,
在spring的配置文件applicationContext.xml中,添加<aop:aspectj-autoproxy>
,加上属性
proxy-target-class = “true”
,也就是<aop:aspectj-autoproxy proxy-target-class = “true”>
</aop:aspectj-autoproxy>
,这样就是使用了类的动态代理。
解释说明:proxy-target-class
的属性值决定是基于接口的动态代理还是基于类的代理被创建
proxy-target-class = true
当它的属性值设置为true的时候,是使用基于类的动态代理,需要引入cglib的依赖。
proxy-target-class = false
当它的属性值设置为false或者是不设置为默认值的时候,是使用jdk的接口的动态代理,标准的jdk的动态代理将会起作用。
(4)总结:分析问题尽量多看Caused by里面的内容。