如何使用struts的select标签？

如何使用struts的select标签？

页面的标签
<html:select property='voltage'>
<html:options collection="projectItems" labelProperty="label" property="value"/>
</html:select>

后台的型成，LabelValueBean是struts的内部标签
Vector projectItems=new Vector(4);
projectItems.add(0,new LabelValueBean("项目部1","1"));
projectItems.add(1,new LabelValueBean("项目部2","2"));
projectItems.add(2,new LabelValueBean("项目部3","3"));
projectItems.add(3,new LabelValueBean("项目部4","4"));
request.setAttribute("projectItems",projectItems);//projectItmes得和collection=""的值必须相同