定义StringBuilder拼接多个字符串，以逗号分隔。通过循环遍历数据集合，将非空的CODE值逐个追加到StringBuilder中。若结果非空，则去除首字符逗号，最后转换为String类型返回。
StringBuilder creditCode = new StringBuilder();
for (int i = 0; i < data.size(); i++) {String rowCode = data.get(i).get("CODE");if(!"".equals(rowCode) ){creditCode.append(",").append(rowCode);}}if(creditCode.length()>0){creditCode = new StringBuilder(creditCode.substring(1));}
String code = creditCode.toString();
