java.lang.ClassCastException：java.lang.Class无法强制转换为java.lang.reflect.ParameterizedType
我使用generics创建了接口和类的层次结构，并搞砸了所有内容。
最顶级的类是AbstractJpaEntity，它由所有域实体扩展
@MappedSuperclass @EntityListeners({AbstractJpaEntity.AbstractEntityListener.class}) @SuppressWarnings("serial") public class AbstractJpaEntity implements Serializable ProductTypeDomain类就像分隔出几个表实体的标记类一样。
@SuppressWarnings("serial") @MappedSuperclass @EntityListeners({ ProductTypeDomain.AbstractEntityListener.class }) public class ProductTypeDomain extends AbstractJpaEntity{}
接口“GenericDao”定义
public interface GenericDao {...
抽象类GenericDaoImpl（此类具有通用函数，如persist，merge）
public abstract class GenericDaoImpl implements GenericDao {...
接口ProductTypeDao
public interface ProductTypeDao extends GenericDao {
Spring存储库类ProductTypeDaoImpl
@Repository("productTypeDao") public class ProductTypeDaoImpl extends GenericDaoImpl implements ProductTypeDao {....
在Spring服务类ProductManagerServiceimpl中，我正在自动assembly存储库productTypeDao
@Service("productManager") public class ProductManagerServiceimpl implements ProductManagerService{ @Autowired ProductTypeDao productTypeDao;
在运行代码时，它给了我以下错误
引起：org.springframework.beans.factory.BeanCreationException：无法自动assembly字段：com.jodo.cms.service.ProductManagerService com.jodo.cms.controllers.ProductController.productManager; 嵌套exception是org.springframework.beans.factory.BeanCreationException：创建名为’productManager’的bean时出错：注入自动连接的依赖项失败; 嵌套exception是org.springframework.beans.factory.BeanCreationException：无法自动assembly字段：com.jodo.cms.dao.ProductTypeDao com.jodo.cms.service.impl.ProductManagerServiceimpl.productTypeDao; 嵌套exception是org.springframework.beans.factory.BeanCreationException：创建文件中定义名为’productTypeDao’的bean时出错[/ home / jodo / Server / Tomcat / webapps / jodocms / WEB-INF / classes / com / jodo / cms / dao / impl / ProductTypeDaoImpl.class]：bean的实例化失败; 嵌套exception是org.springframework.beans.BeanInstantiationException： 无法实例化bean类[com.jodo.cms.dao.impl.ProductTypeDaoImpl]：构造函数抛出exception; 嵌套exception是java.lang.ClassCastException：java.lang.Class无法强制转换为java.lang.reflect.ParameterizedType
Full Stacktrace is ------------------------------- 09:24:29,443 INFO XmlWebApplicationContext:1020 - Closing Root WebApplicationContext: startup date [Tue Apr 15 08:38:10 IST 2014]; root of context hierarchy 09:24:29,445 INFO DefaultListableBeanFactory:433 - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@153a859b: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,productTypeDao,productEntityDao,productCategoryDao,categoryTreeDao,categoryEntityDao,categoryManager,productManager,dataSource,entityManagerFactory,transactionManager,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,log4jInitialization,org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor#0]; root of factory hierarchy 09:24:29,460 INFO LocalContainerEntityManagerFactoryBean:441 - Closing JPA EntityManagerFactory for persistence unit 'default' 09:24:29,461 INFO SessionFactoryImpl:927 - closing 09:24:41,129 INFO DefaultListableBeanFactory:433 - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@c27de92: defining beans [productController,categoryController,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0,org.springframework.format.support.FormattingConversionServiceFactoryBean#0,org.springframework.validation.beanvalidation.LocalValidatorFactoryBean#0,org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#0,org.springframework.web.servlet.handler.MappedInterceptor#0,org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver#0,org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver#0,org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver#0,org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor#0]; parent: org.springframework.beans.factory.support.DefaultListableBeanFactory@5803bbcc 09:24:41,134 ERROR DispatcherServlet:457 - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.jodo.cms.service.ProductManagerService com.jodo.cms.controllers.ProductController.productManager; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productManager': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.jodo.cms.dao.ProductTypeDao com.jodo.cms.service.impl.ProductManagerServiceimpl.productTypeDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productTypeDao' defined in file [/home/jodo/Server/Tomcat/webapps/jodocms/WEB-INF/classes/com/jodo/cms/dao/impl/ProductTypeDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.jodo.cms.dao.impl.ProductTypeDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:631) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:588) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:645) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:508) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:449) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1279) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1192) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5210) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5493) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:632) at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1073) at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1857) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:744) Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.jodo.cms.service.ProductManagerService com.jodo.cms.controllers.ProductController.productManager; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productManager': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.jodo.cms.dao.ProductTypeDao com.jodo.cms.service.impl.ProductManagerServiceimpl.productTypeDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productTypeDao' defined in file [/home/jodo/Server/Tomcat/webapps/jodocms/WEB-INF/classes/com/jodo/cms/dao/impl/ProductTypeDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.jodo.cms.dao.impl.ProductTypeDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:506) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284) ... 33 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productManager': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.jodo.cms.dao.ProductTypeDao com.jodo.cms.service.impl.ProductManagerServiceimpl.productTypeDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productTypeDao' defined in file [/home/jodo/Server/Tomcat/webapps/jodocms/WEB-INF/classes/com/jodo/cms/dao/impl/ProductTypeDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.jodo.cms.dao.impl.ProductTypeDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:269) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:848) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:790) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478) ... 35 more Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.jodo.cms.dao.ProductTypeDao com.jodo.cms.service.impl.ProductManagerServiceimpl.productTypeDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productTypeDao' defined in file [/home/jodo/Server/Tomcat/webapps/jodocms/WEB-INF/classes/com/jodo/cms/dao/impl/ProductTypeDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.jodo.cms.dao.impl.ProductTypeDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:506) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284) ... 48 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productTypeDao' defined in file [/home/jodo/Server/Tomcat/webapps/jodocms/WEB-INF/classes/com/jodo/cms/dao/impl/ProductTypeDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.jodo.cms.dao.impl.ProductTypeDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:997) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:943) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:848) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:790) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478) ... 50 more Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.jodo.cms.dao.impl.ProductTypeDaoImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:162) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:76) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:990) ... 61 more Caused by: java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType at com.jodo.cms.dao.impl.GenericDaoImpl.(GenericDaoImpl.java:42) at com.jodo.cms.dao.impl.ProductTypeDaoImpl.(ProductTypeDaoImpl.java:19) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147) ... 63 more
class GenericDaoImpl详细信息
public abstract class GenericDaoImpl implements GenericDao { protected Class entityClass; Logger logger = Logger.getLogger(GenericDaoImpl.class); @PersistenceContext protected EntityManager em; public EntityManager getEntityManager() { return this.em; } @SuppressWarnings("unchecked") public GenericDaoImpl() { ParameterizedType genericSuperclass = (ParameterizedType) getClass().getGenericSuperclass(); this.entityClass = (Class) genericSuperclass.getActualTypeArguments()[0]; } public void persist(T entity) throws JodoException { try { em.persist(entity); em.flush(); } catch (ConstraintViolationException cve) { throw new JodoException(cve.getCause(), "constraints violated", cve); } }...
我无法更改AbstractJpaEntity，GenericDao和GenericDaoImpl，因为它已经用于合并许多其他未扩展ProductTypeDomain的实体。
谢谢
在这个类声明中
public class ProductTypeDaoImpl extends GenericDaoImpl implements ProductTypeDao
您使用GenericDaoImpl和ProductTypeDao作为原始类型。 首先阅读为什么不应该使用它们。
您使用原始类型的事实会导致问题
ParameterizedType genericSuperclass = (ParameterizedType) getClass().getGenericSuperclass();
其中getGenericSuperclass()将返回一个自GenericDaoImpl以来的Class实例
public class ProductTypeDaoImpl extends GenericDaoImpl implements ProductTypeDao
未参数化，因此不是ParameterizedType 。 演员然后失败了。
解决方案是在类声明中参数化两种类型。 从代码中可以直接看出那些类型参数应该是什么，但GenericTypeDao应该采用ProductTypeDomain
public class ProductTypeDaoImpl extends GenericDaoImpl implements ProductTypeDao
你的界面ProductTypeDao应该被声明为
public interface ProductTypeDao extends GenericDao {
这是一个解决方案
public TO getTo() throws Exception { if(to == null) { try { to = ((Class) ((ParameterizedType) this.getClass().getGenericSuperclass()) .getActualTypeArguments()[0]).newInstance(); } catch(ClassCastException cce) { cce.printStackTrace(); to = ((Class ) ((ParameterizedType) (((Class ) this.getClass() .getAnnotatedSuperclass().getType()).getGenericSuperclass())) .getActualTypeArguments()[0]).newInstance(); } } return to; }