实现一个实体类的序列化和反序列化

面试题，实现一个实体类的序列化和反序列化

public class Test {    private int id;    private String name;    private Integer age;    //set/get略    }class User{    public static void main(String[] args) throws IOException, ClassNotFoundException {        //序列化        ObjectOutputStream putStream = new ObjectOutputStream(new FileOutputStream("path"));        putStream.writeObject(test);        putStream.flush();        putStream.close();        //反序列化        ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("path"));        for(;;){             Object object=inputStream.readObject();                if (object==null){                    break;                }                System.out.println(object);            }            inputStream.close();        }}

实现当前月份的上一个月的算法

//计算当前时间的上一个月        1.假如PayYm是当前月在实体类中        String payYm = bonusInfo.getPayYm();        Integer month = Integer.parseInt(payYm.substring(payYm.length()-1, payYm.length()));        if (month >= 2 && month <= 12) {            month = month-1;        }else if (month == 1) {            month = 12;        }        //得到当前月和当前月的上一个月，发送到页面        model.addAttribute("payYm",bonusInfo.getPayYm());        model.addAttribute("payYmShang",payYm);