java生成json数据

response.setContentType("application/x-json;charset=GBK");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Cache-Control", "no-store");
response.setDateHeader("Expires", 0); 
PrintWriter pw=null;
try {
pw = (PrintWriter)response.getWriter();
        Map result = new HashMap();
        modal = serviceResponse.getModel();
        List bankList = (List)modal.get(ServiceResponse.SERVICE_RESPONSE_RESULT);
        Iterator it = bankList.iterator();
        while(it.hasNext()){
        BankDTO bankDTO_json = (BankDTO)it.next();
        result.put(bankDTO_json.getBankNo(), bankDTO_json);
        }
        JSONObject jsonList = JSONObject.fromObject(result);
        pw.print(jsonList);