图片删除工具类，ioc注入异常

Question

老师您好，跟着老师前边的进度做挺顺利，但是在编写图片删除，修改的工具类时。spring的ioc静态注入dao接口的出现了空指针异常，事务曾那边的注入还是正常的。

然后我将工具类中的@Autowired注入 换成了（set）的方法注入

然后，运行的时候说我的注入：类型异常
这是我持久层接口方法

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'fileUtil' defined in file [F:ideaSpacedeact_dianping	argetdeact_dianpingWEB-INFclassesspringapplicationContext_util.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String' to required type 'org.ct.dao.IAdDao' for property 'adDao'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'org.ct.dao.IAdDao' for property 'adDao': no matching editors or conversion strategy found
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:601)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
	at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:701)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:667)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:715)
	at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:590)
	at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:529)
	at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:169)
	at javax.servlet.GenericServlet.init(GenericServlet.java:158)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1079)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:973)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4885)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5199)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:743)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:719)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:714)
	at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1720)
	at sun.reflect.GeneratedMethodAccessor148.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:287)
	at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
	at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
	at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:483)
	at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:432)
	at sun.reflect.GeneratedMethodAccessor146.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:287)
	at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
	at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
	at com.sun.jmx.remote.security.MBeanServerAccessController.invoke(MBeanServerAccessController.java:468)
	at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)
	at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
	at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1408)
	at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)
	at sun.reflect.GeneratedMethodAccessor78.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)
	at sun.rmi.transport.Transport$1.run(Transport.java:200)
	at sun.rmi.transport.Transport$1.run(Transport.java:197)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
	at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String' to required type 'org.ct.dao.IAdDao' for property 'adDao'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'org.ct.dao.IAdDao' for property 'adDao': no matching editors or conversion strategy found
	at org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:590)
	at org.springframework.beans.AbstractNestablePropertyAccessor.convertForProperty(AbstractNestablePropertyAccessor.java:604)
	at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:219)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1730)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1686)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1433)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592)
	... 62 more
Caused by: java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'org.ct.dao.IAdDao' for property 'adDao': no matching editors or conversion strategy found
	at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:262)
	at org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:585)
	... 68 more

然后，我就不知道该从哪个角度去查找这个错的原因了。

Answer 1

源生活 2019-10-04 17:20:23

工具类里最好不要注入dao，可以service里注入，调用工具类时传入dao。

Answer 2

源生活 2019-10-04 17:18:34

配置文件里这样配可能有问题，是用配置文件初始化bean的时候，你配的类名被当成了普通字符串，这个问题在网上搜一下。还有，我没明白你说的如果不用set+配置文件的方式，直接用注解。会有什么问题？

• 提问者 慕侠935299 #1

  直接注入运行的时整个程序的时候没有异常，但是在调用这个工具类的adDao的删除、插入之类的方法时候，就会抛出空指针异常。工具类的adDao应该是注入失败了。然后注解的方法，我不知道怎么去找这个错，我就换成了set+配置文件的方法

Answer 3

源生活 2019-10-04 17:15:50

需要的类型是dao，注入时的类型却是String，看下这个怎么回事，我看你截的图中看不出来，看下还有没有其他地方注入类型弄错了

• 提问者 慕侠935299 #1

  servie层，@Autowired注入adDao 调用增删查改又是正常的。恩，基于看到效果，我就用了直接注入dao方法，我先换成service，然后在那里调用试一试

• 源生活 回复 提问者 慕侠935299 #2

  你工具类里注入后，调用的方法是静态方法？

• 提问者 慕侠935299 回复 源生活 #3

  改成了servie，还是空指针异常。额，之前工具类用静态方法，然后运行不起来。我把工具类的静态就去调用了。然后调用的时候直接适用的匿名调用的。new FileUtil().adDelete()    
  delete =new FileUtil().adDelete(saveAdImgPath, id);
  程序上好像没什么毛病，的样子

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