请教问题attempt to create saveOrUpdate event with null

Action中得不到jsp页面表单中的值，大家帮忙看一下哪里错了。
jsp页面：



<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

    <%@ taglib uri="/struts-tags" prefix="s" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8">

<title>Insert title here</title>

</head>

<body>

<s:form action="insert" namespace="/hwinfo">

  <s:textfield label="主板" name="hwinfo.motherboard" /> 

  <s:textfield label="芯片" name="hwinfo.chipset" />

  <s:submit value="提交" /> 

</s:form>

</body>

</html>

XML文件：



<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE struts PUBLIC 

    " -//Apache Software Foundation//DTD Struts Configuration 2.0//EN " 

    " http://struts.apache.org/dtds/struts-2.0.dtd " > 

<struts> 

    <constant name ="struts.devMode" value = "true" /> 

    <constant name = "struts.configuration.xml.reload" value = "true" /> 

    <constant name = "struts.action.extension" value = "action" /> 

&lt;package name = "default" extends = "struts-default"&gt; 
    &lt;action name = "admincp"&gt; 
        &lt;result&gt;/admin/login.jsp&lt;/result&gt; 
    &lt;/action&gt;       
&lt;/package&gt; 


<package name = "hwinfo" extends = "struts-default" namespace = "/hwinfo"> 

        <action name="insert" class="hwInfoAction" method="insertHwinfo">

             <result name="success">/hwinfo/hardwareinfo.jsp</result>

             <result name="input">index.jsp</result>

        </action>


    </package> 

</struts>

Action：



public class HwInfoAction extends ActionSupport{

    /**

     * 

     */

    private static final long serialVersionUID = 1L;

    private int hwid;

    private String motherboard;

    private String chipset;


    private HwInfo hwinfo;

    private HwInfoDao hwInfoDao;

public void setHwid(int hwid){
    this.hwid=hwid;
}
public int getHwid(){
    return hwid;
}

public void setMotherboard(String motherboard){
    this.motherboard=motherboard;
}
public String getMotherboard(){
    return motherboard;
}

public void setChipset(String chipset ){
    this.chipset=chipset;
}

 public String getChipset(){
        return chipset;
    }

public void setHwInfo(HwInfo hwinfo){
    this.hwinfo=hwinfo;
}
public HwInfo getHwInfo(){
    return hwinfo;
}
public void setHwInfoDao(HwInfoDao hwInfoDao){
    this.hwInfoDao=hwInfoDao;
}
public HwInfoDao getHwInfoDao(){
    return hwInfoDao;
}

public String execute(){
    return "success";
}

public String insertHwinfo(){

    if(hwInfoDao.insertHwinfo(hwinfo))
        return "seccess";
    else
        return "false";
}


}

实在找不出问题了，大家帮忙看看吧！
问题补充：
在action类里面看hwinfo的值，始终是Null，得不到表单传递过来的值

很明显form表单的值传不到给action, HwInfoAction 必须这样写
private HwInfo hwinfo = [b]new HwInfo ()[/b];

public HwInfo getHwinfo()
{
return hwinfo;
}

而HwInfo类的两个属性motherboard和chipset必须提供setXXX和getXXX两种方法

是不是数据库中表字段有必填的

同楼上,如果用Webwork的ioc 是不会创建POjo的
这10分... 分贬值了