why after validation，return zero？

i use struts-validator for validation：and my code is：

actionform ：

validation:

<form name="ZiGuanForm">
        <field property="xu_hao" depends="required,maxlength">
                   <msg name="required" key="errors.required"/>
                   <msg name="maxlength" key="errors.maxlength"/>
                   <arg0 key="ziGuan.xu_hao"/>
                   <arg1 name="maxlength" key="${var:maxlength}" resource="false" />
                   <var>
                       <var-name>maxlength</var-name>
                       <var-value>1</var-value>
                   </var>
                </field>
 
        <field property="zhuang_tai" depends="required">
                   <msg name="required" key="ziGuan.required"/>
                   <arg0 key="ziGuan.zhuang_tai"/>
                </field>
        
        <field property="guan_kong_id" depends="required,mask">
                   <msg name="required" key="ziGuan.required"/>
                   <msg name="mask" key="errors.mask"/>
                   <arg0 key="ziGuan.guan_kong_id"/>
                   <arg1 name="mask" key="${var:mask}" resource="false"/>
                   <var>
                       <var-name>mask</var-name>
                       <var-value>^[0-9]*$</var-value>
                   </var>   
                </field>
        <field property="dian_lan_d_id" depends="required,mask">
                   <msg name="required" key="ziGuan.required"/>
                   <arg0 key="ziGuan.dian_lan_d_id"/>
                   <arg1 name="mask" key="${var:mask}" resource="false"/>
                   <var>
                       <var-name>mask</var-name>
                       <var-value>^[0-9]*$</var-value>
                   </var>   
                </field>
        <field property="guang_lan_d_id" depends="required,mask">
                   <msg name="required" key="ziGuan.required"/>
                   <arg0 key="ziGuan.guang_lan_d_id"/>
                   <arg1 name="mask" key="${var:mask}" resource="false"/>
                   <var>
                       <var-name>mask</var-name>
                       <var-value>^[0-9]*$</var-value>
                   </var>   
                </field>
       </form>

jsp:

<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>
<html:html>
<head>
<link rel="stylesheet" href="<%=request.getContextPath()%>/style/normal.css" type="text/css" media="screen, print" />
<script src="<%=request.getContextPath()%>/style/setday.js"></script>
</head>
 
<body>
<html:form action="addZiGuan.do?action=insert" method="post">
<br/>
<logic:messagesPresent>
   <ul>
   <html:messages id="error">
      <li><font color="red"><bean:write name="error"/></font></li>
   </html:messages>
   </ul><hr>
</logic:messagesPresent>
  <table border="1" align="center">
     <tr >
      <th colspan=2 class="hth"><bean:message key="ziGuan.insert.title"/></th>
    </tr>
    <tr>
      <th scope="row"><bean:message key="ziGuan.xu_hao"/></th>
      <td><html:text property="xu_hao" size="60"/></td>
    </tr>
    <tr>
      <th scope="row"><bean:message key="ziGuan.zhuang_tai"/></th>
      <td><html:text property="zhuang_tai" size="60"/></td>
    </tr>
    <tr>
      <th scope="row"><bean:message key="ziGuan.guan_kong_id"/></th>
      <td><html:text property="guan_kong_id" size="60"/></td>
    </tr>
    <tr>
      <th scope="row"><bean:message key="ziGuan.dian_lan_d_id"/></th>
      <td><html:text property="dian_lan_d_id" size="60"/></td>
    </tr>
    <tr>
      <th scope="row"><bean:message key="ziGuan.guang_lan_d_id"/></th>
      <td><html:text property="guang_lan_d_id" size="60"/></td>
    </tr>
  <tr align="center">
    <td colspan=2>
      <html:submit property="Submit">
         <bean:message key="button.submit"/>
      </html:submit>
      <html:cancel>
         <bean:message key="button.cancel"/>
      </html:cancel>
    </td>
  </tr>
  </table>
</html:form>
</body>
</html:html>

i found that, when i enter in jsp,some field already has value "0",but i want them not display any value at all when i enter jsp.
how can i do?
thanks

why after validation&#65292;return zero&#65311;

why after validation，return zero？