ajax+struts完成三级联动下拉框

"text/javascript">   
        var req;   
        window.onload=function(){   
        }   
           
        function Change_Select()   
        {   
            var zhi=document.getElementById('select1').value;   
            var url="doSelect.do?method=getSelect2&id="+zhi;   
            if(zhi=="0"){   
                alert("请选择您要察看的信息");   
                   return;   
            }else{   
                if(window.XMLHttpRequest)   
                {   
                    req=new XMLHttpRequest();   
                }else if(window.ActiveXObject)   
                {   
                    req=new ActiveXObject("Microsoft.XMLHTTP");   
                }   
                   
                if(req)   
                {   
                    req.open("GET",url,true);   
                    req.onreadystatechange=callback;   
                    req.send(null);   
                }   
            }   
        }   
           
        function Change_Select2()   
        {   
            var zhi=document.getElementById('select2').value;   
            //alert(zhi.substring(0,2));   
            if(zhi=="0"){   
                alert("请选择您要察看的信息");   
                   return;   
               }   
            if(true){   
                var url="doSelect.do?method=getSelect3&id="+zhi;   
                if(window.XMLHttpRequest)   
                {   
                    req=new XMLHttpRequest();   
                }else if(window.ActiveXObject)   
                {   
                    req=new ActiveXObject("Microsoft.XMLHTTP");   
                }   
                   
                if(req)   
                {   
                    req.open("GET",url,true);   
                    req.onreadystatechange=callback2;   
                    req.send(null);   
                }   
            }else{   
                parent.topFram.location ="sqdSelectAll.go?method=getlistAll&id="+zhi;   
            }   
        }   
           
        function Change_Select3()   
        {   
            var zhi=document.getElementById('m_lbbm_th').value;   
            //alert(zhi.substring(0,2));   
            if(zhi=="0"){   
                alert("请选择您要察看的信息");   
                   return;   
               }else{   
                parent.topFram.location ="sqdSelectAll.go?method=getlistAll2&id="+zhi;   
            }   
        }   
           
        function callback()   
        {   
            if(req.readyState == 4)   
            {   
                if(req.status == 200)   
                {   
                    parseMessage();   
                }else{   
                    alert("Not able to retrieve description"+req.statusText);   
                }   
            }   
        }   
           
        function callback2()   
        {   
            if(req.readyState == 4)   
            {   
                if(req.status == 200)   
                {   
                    parseMessage2();   
                }else{   
                    alert("Not able to retrieve description"+req.statusText);   
                }   
            }   
        }   
function parseMessage()   
        {   
            var xmlDoc=req.responseXML.documentElement;   
            var xSel=xmlDoc.getElementsByTagName('select');   
            var select_root=document.getElementById('select2');   
            select_root.options.length=0;   
               
            for(var i=0;i
            {   
                var xValue=xSel[i].childNodes[0].firstChild.nodeValue;   
                var xText=xSel[i].childNodes[1].firstChild.nodeValue;   
                var option=new Option(xText,xValue);   
                try{   
                    select_root.add(option);   
                }catch(e){   
                }   
            }   
        }   
           
        function parseMessage2()   
        {   
            var xmlDoc=req.responseXML.documentElement;   
            var xSel=xmlDoc.getElementsByTagName('select');   
            var select_root=document.getElementById('select3');   
            select_root.options.length=0;   
               
            for(var i=0;i
            {   
                var xValue=xSel[i].childNodes[0].firstChild.nodeValue;   
                var xText=xSel[i].childNodes[1].firstChild.nodeValue;   
                var option=new Option(xText,xValue);   
                try{   
                    select_root.add(option);   
                }catch(e){   
                }   
            }   
        }                           
      
2、html代码
   



xml 代码
<html:form action="/doSelect.do"  >    
    <TABLE class = "cbToolbar" id = "idToolbar" cellpadding = '0' cellspacing = '0'>  
        <TR align = "left" valign = "top" >  
            <TD  NOWRAP> 物质类别:     
                <html:select  property="select1" onchange="Change_Select()">  
                    <html:option value="0">请选择html:option>  
                       <html:options collection="list1" property="typId" labelProperty="typName"/>  
                html:select>     
                   
                   
                <html:select property="select2" styleId="m_lbbm_se" onchange="Change_Select2()">  
                    <html:option value="0">   html:option>  
                html:select>  
                <html:select property="select3" styleId="m_lbbm_th" onchange="Change_Select3()">  
                    <html:option value="0">   html:option>  
                html:select>  
  
            TD>  
               
        tr>  
    table>  
     html:form>   



3、控制器源码

java 代码
public ActionForward list1(   
  ActionMapping mapping,   
  ActionForm form,   
  HttpServletRequest request,   
  HttpServletResponse response) {   
  
  String lan = (String)request.getSession().getAttribute("languageType");   
  if(lan==null)lan ="1";    
     
  String HQL = "from Type t where t.typLang= :lang  and t.leve=:leve order by t.typOrder";   
  Query query = dao.getHQLQuery(HQL);   
  query.setString("lang",lan);   
  query.setInteger("leve",2);   
     
  List types = query.list();   
  request.setAttribute("list1",types);   
  return mapping.findForward("list");   
}   
  
    
    
public ActionForward getSelect2(   
   ActionMapping mapping,   
   ActionForm form,   
   HttpServletRequest request,   
   HttpServletResponse response) {   
     
  String lan = (String)request.getSession().getAttribute("languageType");   
  if(lan==null)lan ="1";    
     
  String id=request.getParameter("id");   
           
  response.setContentType("text/xml;charset=UTF-8");   
  response.setHeader("Cache-Control","no-cache");   
        String xml_start="<?xml version=\"1.0\" encoding=\"UTF-8\"?>";   
        xml_start+="<selects>";   
        String xml_end="</selects>";   
        String xml="<select><value>"+"0"+"</value><text>"+"select"+"</text></select>";   
        String m_lbbm_se="";   
        String m_lbmc_se="";   
        List LbfList=null;   
          
        LbfList=getList(3,lan,new Integer(id).intValue());   
          
        Iterator it=LbfList.iterator();   
        while(it.hasNext()){   
            Type cgsqd=(Type)it.next();   
            m_lbbm_se=cgsqd.getTypId().toString();   
            m_lbmc_se=cgsqd.getTypName();   
            xml +="<select><value>"+m_lbbm_se+"</value><text>"+m_lbmc_se+"</text></select>";   
        }   
        String last_xml=xml_start+xml+xml_end;   
        try {   
         System.out.println(last_xml);   
         response.getWriter().write(last_xml);   
        } catch (IOException e) {   
            e.printStackTrace();   
        }   
        return null;   
  
  }   
    
public ActionForward getSelect3(   
   ActionMapping mapping,   
   ActionForm form,   
   HttpServletRequest request,   
   HttpServletResponse response) {   
  
  String lan = (String)request.getSession().getAttribute("languageType");   
  if(lan==null)lan ="1";    
     
  String id=request.getParameter("id");   
           
  response.setContentType("text/xml;charset=UTF-8");   
  response.setHeader("Cache-Control","no-cache");   
        String xml_start="<?xml version=\"1.0\" encoding=\"UTF-8\"?>";   
        xml_start+="<selects>";   
        String xml_end="</selects>";   
        String xml="<select><value>"+"0"+"</value><text>"+"select"+"</text></select>";   
        String m_lbbm_se="";   
        String m_lbmc_se="";   
        List LbfList=null;   
          
        LbfList=getList_product(lan,new Integer(id).intValue());   
          
        Iterator it=LbfList.iterator();   
        while(it.hasNext()){   
            Product cgsqd=(Product)it.next();   
            m_lbbm_se=cgsqd.getProId().toString();   
            m_lbmc_se=cgsqd.getProName();   
            xml +="<select><value>"+m_lbbm_se+"</value><text>"+m_lbmc_se+"</text></select>";   
        }   
        String last_xml=xml_start+xml+xml_end;   
        try {   
         System.out.println(last_xml);   
         response.getWriter().write(last_xml);   
        } catch (IOException e) {   
            e.printStackTrace();   
        }   
        return null;   
  
  }   
    
    
private List getList(int lb,String lan,int parent_id){   
     
  String HQL = "from Type t where t.typLang= :lang  and t.leve=:leve and t.type.typId=:pid order by t.typOrder";   
  Query query = dao.getHQLQuery(HQL);   
  query.setString("lang",lan);   
  query.setInteger("leve",lb);   
  query.setInteger("pid",parent_id);   
     
  List types = query.list();   
  return types;   
}   
    
private List getList_product(String lan,int typeid){   
     
  String HQL = "from Product p where p.proLang= :lang   and p.type.typId=:typeid order by p.proOrder";   
  Query query = dao.getHQLQuery(HQL);   
  query.setString("lang",lan);   
  query.setInteger("typeid",typeid);   
     
  List lists = query.list();   
  return lists;   
}