Cannot assign value of type ‘java.lang.String’ to property ‘file’ of type &#

Exception：

org.apache.commons.beanutils.ConversionException: Cannot assign value of type 'java.lang.String' to property 'file' of type 'org.apache.struts.upload.FormFile'
    at org.apache.struts.action.DynaActionForm.set(DynaActionForm.java:423)
    at org.apache.commons.beanutils.PropertyUtils.setSimpleProperty(PropertyUtils.java:1769)
    at org.apache.commons.beanutils.PropertyUtils.setNestedProperty(PropertyUtils.java:1684)
    at org.apache.commons.beanutils.PropertyUtils.setProperty(PropertyUtils.java:1713)
    at org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:1019)
    at org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:808)
    at org.apache.struts.util.RequestUtils.populate(RequestUtils.java:1252)
    at org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:821)
    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:254)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1481)
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
    at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:1006)
    at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:419)
    at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:315)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6718)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
    at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3764)
    at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2644)
    at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:219)
    at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:178)
>

 

SOLUTION：

add "enctype='multipart/form-data'" to your action form.,