Spring MVC 2.5, Annotations, Controller, MultipartFile

Hello search-engine user,

The exception you experienced...

org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [org.springframework.web.multipart.MultipartFile]: Specified class is an interface
   at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:75)
   at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:357)
   at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:201)
   at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:128)
   at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:310)
   at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:292)
   at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:875)
   at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:809)
   at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571)
   at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:511)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
   at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
   at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
   at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
   at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
   at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
   at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
   at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
   at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
   at java.lang.Thread.run(Thread.java:613)

... is caused by not annotating your method parameter with @RequestParam.

@RequestMapping("/uploadFile", method=RequestMethod.POST)
public String uploadFile(@RequestParam(value="myFile", required=true) MultipartFile file) {
       ...
}

Since spring does not know what upload parameter goes with MultipartFile without the annotation, it attempts to create a new default instance of the parameter to pass in. It can't do that for an interface, hence the error message.