记录一次泛型的使用经历

private <T>  String  appendProductIds(List<?> links, T obj) {
		String productIdS = "";
		Class<?> clazz = obj.getClass();
		if(clazz.isInstance(ShelfLink.class)) {
			List<ShelfLink> shelfLinks = (List<ShelfLink>) links;
			for (ShelfLink shelfLink : shelfLinks) {
				String productId = String.valueOf(shelfLink.getLinkId());
				if (StringUtil.isEmpty(productIdS)) {
					productIdS = productIdS + productId;
				} else {
					productIdS =productIdS +  "," + productId;
				}
			}
		} else if(clazz.isInstance(CommercialLink.class)) {
			List<CommercialLink> commercialLinks = (List<CommercialLink>) links;
			for (CommercialLink commercialLink : commercialLinks) {
				String productId = String.valueOf(commercialLink.getLinkId());
				if (StringUtil.isEmpty(productIdS)) {
					productIdS = productIdS + productId;
				} else {
					productIdS =productIdS +  "," + productId;
				}
			}
		}
		return productIdS;
	}