json 서버측

    /**
     *     id       
     * @return
     * @throws DataBaseException 
     * @throws IOException 
     */
    public String loadModel() throws DataBaseException, IOException{
        HttpServletRequest request=ServletActionContext.getRequest();
        HttpServletResponse response=ServletActionContext.getResponse();
        
        response.setContentType("application/x-javascript;charset=UTF-8");  
        PrintWriter out = response.getWriter();
        
        String brandId = request.getParameter("brandId");
        List phones = this.phoneService.queryMobilByBrandId(Integer.parseInt(brandId));
        if(phones!=null&&phones.size()>0){
            //        json  
            JSONArray json=JSONArray.fromObject(phones);
            out.println(json.toString());
            out.close();
        }else{
            out.println("[{id:0,model:'   '}]");        
            out.close();
        }
        return SUCCESS;
    }

function loadPhone(value){
   alert(value);
   $.ajax({
      type: "post",
      url: "supply!loadPhone.do",
      data: ({brandId: value}),
      success: function(data){
         var objs=eval("("+data+")"); 
         var $phone=$("#phone");
         $phone.empty();
         //$phone.append("<option value='0'>..   ..</option>");
         for(var i=0;i<objs.length;i++){           
            $phone.append("<option value='"+objs[i].id+"'>"+objs[i].model+"</option>");   
         }
      }
   }); 
}

<select id="brand" name="brandId" onchange="loadPhone(this.options[this.options.selectedIndex].value)">