maven快速入门番外篇——使用maven整合SSH报错：java.lang.IllegalStateException: Cannot convert value of type...

布满荆棘的人生 2023-06-25 08:15 19阅读 0赞

# 问题描述 #

今天我使用maven整合SSH时，创建了一个如下结构的聚合工程。  
![在这里插入图片描述][20191227142534234.png]  
从上图可以看出，我的项目结构是一个父工程与多个子工程。其中，crm-web子工程依赖于crm-service子工程，crm-service子工程又依赖于crm-dao子工程。当所有子工程的代码开发好之后，通过crm-web子工程的pom.xml文件中配置的tomcat7插件来运行crm-web子工程时，该子工程确实是部署到tomcat服务器上去了，并成功运行起来了，如下图所示。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]  
但是，通过Google Chrome浏览器访问`http://localhost:8080/crm/customer_list`这样的url地址时，给我报错了，错误提示信息如下图所示。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 1]  
下面是更精准的错误提示信息。仔细看看，你知道出错的根本原因了吗？

java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy51 implementing com.meimeixia.crm.service.ICustomerService,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [com.meimeixia.crm.service.impl.CustomerService] for property 'customerService': no matching editors or conversion strategy found
    	org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:302)
    	org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:576)
    	org.springframework.beans.AbstractNestablePropertyAccessor.convertForProperty(AbstractNestablePropertyAccessor.java:603)
    	org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:204)
    	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1527)
    	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1486)
    	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1226)
    	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
    	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    	org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:325)
    	org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    	org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1048)
    	com.opensymphony.xwork2.spring.SpringObjectFactory.buildBean(SpringObjectFactory.java:161)
    	com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:178)
    	com.opensymphony.xwork2.factory.DefaultActionFactory.buildAction(DefaultActionFactory.java:22)
    	com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:148)
    	com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:295)
    	com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:395)
    	com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:194)
    	org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
    	org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:37)
    	com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
    	org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:554)
    	org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
    	org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)

# 出错原因 #

根据上面详细的错误提示信息可知，报错的根本原因就是Spring在转换时，主要是将代理类转换成接口，而不能转换成实际类。

# 解决办法 #

在使用Spring进行aop开发的时候，需要设置proxy-target-class这个属性的值，以决定是基于接口还是类被代理，若proxy-target-class属性的值为true，则表示是基于类被代理。

所以，要想解决这个问题，我们需要在crm-service子模块的applicationContext-service.xml配置文件中配置aop时，注明可以基于类被代理，即在`<aop:cnfig>`标签上添加`proxy-target-class="true"`。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 2]

[20191227142534234.png]: https://img-blog.csdnimg.cn/20191227142534234.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/2019122714254197.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191227142547317.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20191227144735268.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9saWF5dW4uYmxvZy5jc2RuLm5ldA==,size_16,color_FFFFFF,t_70