java中获取当前年月日使用Calendar类
//获取Calendar类
Calendar calendar = Calendar.getInstance();
//获取年
calendar.get(Calendar.YEAR);
//获取月 注：获取的月比真实月少1
calendar.get(Calendar.MONTH)+1;
获取UUID字符串方法:uuid中有-，所以可以用replace替换掉
UUID uuid = UUID.randomUUID();
String uuidString = uuid.toString().replace("-","");