Gson gson = new Gson();
Sell sell = new sell();
Sell sell1 = gson.fromJson(SellJson,Sell.class);//json字符串转对象
String text = gson.toJson(sell);//对象转字符串  map、list转字符串
//  listJson字符串转为list
Type type = new TypeToken<ArrayList<String>>() {  
}.getType();  
ArrayList<String> sList=gson.fromJson(listJsonStr, type);  

public static OrderDTO convert(OrderForm orderForm) {
    List<OrderDetail> orderDetailList = new ArrayList<>();
    Gson gson = new Gson();
    OrderDTO orderDTO = new OrderDTO();
try {
    orderDetailList = gson.fromJson(orderForm.getItems(),
    new TypeToken<List<OrderDetail>>(){}.getType());
}catch (Exception e){
    log.error("【对象转换】 错误，string={}",orderForm.getItems());
    throw new SellException(ExceptionEnum.PARAM_ERROE);
}

    orderDTO.setOrderDetailList(orderDetailList);
    return orderDTO;
}