Question

jsp struts的问题

我按书上编写了一个Struts框架的jsp小程序，但运行后总出现以下错误：
exception

javax.servlet.ServletException: java.lang.ClassCastException: abm.UserForm cannot be cast to org.apache.struts.action.Action
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause

java.lang.ClassCastException: abm.UserForm cannot be cast to org.apache.struts.action.Action
org.apache.struts.chain.commands.servlet.CreateAction.createAction(CreateAction.java:98)
org.apache.struts.chain.commands.servlet.CreateAction.getAction(CreateAction.java:68)
org.apache.struts.chain.commands.AbstractCreateAction.execute(AbstractCreateAction.java:91)
org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

还请高手解释一下，是啥问题

Answer 1

abm.UserForm cannot be cast to org.apache.struts.action.Action

zhukaiheihei 的回答不对哦。
struts1里的form只需要继承ActionForm,这里说代码写得有问题。问题很明显，你把 FORM是转型为Action当然不可以的

Answer 2

你的struct-config.xml里面的abm.UserForm 路径有问题，没有映射到action

Answer 3

java.lang.ClassCastException

abm.UserForm 不能转换为 org.apache.struts.action.Action

类型转换错误

到提示的代码处看看

Answer 4

UserForm 这个类有问题，没有继承org.apache.struts.action.Action