java List数据转换为json类型数据

try {//从数据库中取出List数据 
List<CarouselImage> carouselImageList = (List<CarouselImage>) this.carouselImageService.carouselImageList(); 
List<CarouselImageInfo> list = new ArrayList<CarouselImageInfo>(); // 
for (int i = 0; i < carouselImageList.size(); i++) { 
CarouselImage a = carouselImageList.get(i); 
if (a != null && a != new CarouselImage()) { 
//依次循环放入对应已写好的类中 
CarouselImageInfo b = new CarouselImageInfo(); 
b.setId(a.getId()); 
b.setLink(a.getLink()); 
b.setOrderBy(a.getOrderBy()); 
b.setAppImageUrl(a.getAppImageUrl()); 
list.add(b); 
} 
} 
//转为Json 
JSONArray jsonList = JSONArray.fromObject(list); 
JSONObject obj = new JSONObject(); 
JSONObject j = new JSONObject(); 
obj.accumulate("carouselImageList", jsonList); 

j.accumulate("resultCode", "1"); 

j.accumulate("responseObject", obj); 

PrintWriter pw = response.getWriter(); 
pw.print(j); 

} catch (Exception e) { 
JSONObject j = new JSONObject(); 
try { 
PrintWriter pw = response.getWriter(); 
JSONObject errObj = new JSONObject(); 
j.accumulate("resultCode", "0"); 
j.accumulate("errorMessage", e.getMessage()); 
pw.print(j); 
} catch (IOException e1) { 
// TODO Auto-generated catch block 
e1.printStackTrace(); 
} 
} 

return null; 
}