提问 问题标签用户 spring注入activiti的接口问题？？？

spring注入 @Autowired protected RepositoryService repositoryService;

代码把注入的接口转换为子类 RepositoryServiceImpl repositoryServiceImpl=(RepositoryServiceImpl) repositoryService;

抛出的： 严重: Servlet.service() for servlet spring3 threw exception java.lang.ClassCastException: $Proxy26 cannot be cast to org.activiti.engine.impl.RepositoryServiceImpl at com.zx.appsupport.web.activiti.LeaveController.traceProcess(LeaveController.java:869) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:440) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:428) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:920) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:816) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:801) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)。。。。。

看别人这样都可以 我照他的写就有问题