Ajax实现二级或者三级联动下拉框

$.ajax({ url: url + "option=dropdown",
  type: "post",
  data: "znstr=" + str + "&znclass="+ zclass + "",
  datatype: "html",
  error: function(xmlhttprequest) { },
  success: function(data) {
  if(data!="false")
  {  
  if(data.tostring().length > 0)
  {
  cleardrop(znclass);  
  }  
  var vars = new array(); 
  vars = data.tostring().split(',');
  for(var i =0;i< (vars.length) ;i=i+2 )
  {
  switch(znclass)
  {
  case 2:
  $("#citytwo").append(""+vars[i]+"");
  break;
  case 3:
  $("#citythree").append(""+vars[i]+"");
  break;
  case 4:
  $("#cityfour").append(""+vars[i]+"");
  break;
  }
   
  }
  %>
 
  下面看个完整实例
 
  <%@ page contenttype = "text/html; charset=gbk"  import="java.util.*,com.wehave.hyerp.procurement.domain.cgsqd"%>
<%@ taglib uri="struts-html" prefix="html" %>
<%@ taglib uri="struts-logic" prefix="logic" %>
<%@ taglib uri="struts-bean" prefix="bean" %>

   
       
        css教程" href = "../css/olstyle.css">   
       
   

   
   

       
             物质类别:  
               
                    请选择
                      
                 
               
                       
               
               
                       
               
               
           
           
       
   
    

action

public actionforward doselectwzlb(
            actionmapping mapping,
            actionform form,
            https教程ervletrequest req,
            httpservletresponse res) {
        httpsession session = req.getsession();
        usersession usersession =
            (usersession) session.getattribute("usersession");
        permission.setuserid(usersession.getuserid());
        permission.setusername(usersession.getusername());
        permission.setmodulename("m_cgsqd");
        permission.setactionstr("'m_select'");
        if(permissionservice.checkuserpermission(permission)){
            int updatesign=0;
            try{
                cgsqdservice.updatecgsqwzhzb_sqsl();
                updatesign=1;
            }catch(exception e){
                e.printstacktrace();
                updatesign=0;
            }
            if(updatesign==1){
                list lbflist=cgsqdservice.treelistwzlb2();
                req.setattribute("lbflist",lbflist);
                return mapping.findforward("tools");
            }else{
                return null;
            }
        }else{
            return mapping.findforward("failure");
        }
    }
   
    /** *//**
     *
     * 查询物质编码类别列表操作(二级)
     * */
    public actionforward doselectwzlb1(
            actionmapping mapping,
            actionform form,
            httpservletrequest req,
            httpservletresponse res) {
        httpsession session = req.getsession();
        usersession usersession =
            (usersession) session.getattribute("usersession");
        permission.setuserid(usersession.getuserid());
        permission.setusername(usersession.getusername());
        permission.setmodulename("m_cgsqd");
        permission.setactionstr("'m_select'");
        if(permissionservice.checkuserpermission(permission)){
            int updatesign=0;
            try{
                cgsqdservice.updatecgsqwzhzb_sqsl();
                updatesign=1;
            }catch(exception e){
                e.printstacktrace();
                updatesign=0;
            }
            if(updatesign==1){
                list lbflist=cgsqdservice.treelistwzlb2();
                req.setattribute("lbflist",lbflist);
                return mapping.findforward("tools1");
            }else{
                return null;
            }
        }else{
            return mapping.findforward("failure");
        }
    }
   
    /** *//**
     *
     * 查询物质编码类别列表操作(三级)
     * */
    public actionforward getskill(
            actionmapping mapping,
            actionform form,
            httpservletrequest req,
            httpservletresponse res) {
        httpsession session = req.getsession();
        usersession usersession =
            (usersession) session.getattribute("usersession");
        permission.setuserid(usersession.getuserid());
        permission.setusername(usersession.getusername());
        permission.setmodulename("m_cgsqd");
        permission.setactionstr("'m_select'");
        if(permissionservice.checkuserpermission(permission)){
            string id=req.getparameter("id");
           
            res.setcontenttype("text/xml;charset=gbk");
            res.setheader("cache-control","no-cache");
            string xml_start="";
            xml_start+="";
            string xml_end="";
            string xml="0请选择";
            string m_lbbm_se="";
            string m_lbmc_se="";
            list lbflist=null;
            if(id.equals("wy")){
                lbflist=cgsqdservice.treelistwzlb3_2(id);
            }else{
                lbflist=cgsqdservice.treelistwzlb3_1(id);   
            }
            iterator it=lbflist.iterator();
            while(it.hasnext()){
                cgsqd cgsqd=(cgsqd)it.next();
                m_lbbm_se=cgsqd.getm_gykfwzlbb_lbbm();
                m_lbmc_se=cgsqd.getm_gykfwzlbb_lbmc();
                xml +=""+m_lbbm_se+""+m_lbmc_se+"";
            }
            string last_xml=xml_start+xml+xml_end;
            logger.debug("xml是："+last_xml);
            try {
                res.getwriter().write(last_xml);
            } catch (ioexception e) {
                e.printstacktrace();
            }
            return null;
        }else{
            return null;
        }
    }