判断对象是否为空（数据、集合等对象）
public static boolean isEmpty(Object obj) {if (obj == null) {return true;}if (obj.getClass().isArray()) {if (Array.getLength(obj) == 0) {return true;}}if (obj instanceof Collection<?>) {Collection<?> collection = (Collection<?>) obj;if (collection.isEmpty()) {return true;}}if (obj instanceof Map<?, ?>) {Map<?, ?> map = (Map<?, ?>) obj;if (map.isEmpty()) {return true;}}return false;}