java查询指定日期前几个月

1、业务背景

App开发遇到时间轴，一般由后端返回（原因：放在APP端获取时间会随着手机时间调整而变动），现要求返回当前月前n个月及后m个月的月份（包括页面英文简写）。

2、DateUtils方法

 public static final String DATE_YYYY_MM = "yyyy-MM";
/**
     * @name: getMonths
     * @description: 获取指定的月份信息
     * @param offset 偏移量
     * @return: java.lang.String
     * @date: 2020-04-28 13:19
     * @auther: Geroge1226
     *
    */
    public static String getMonths(Date date,int offset) {
        SimpleDateFormat sdf = new SimpleDateFormat(DATE_YYYY_MM);
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.add(Calendar.MONTH, +offset);
        Date m = c.getTime();
        return sdf.format(m);
    }

3、MonthMapperEnum枚举类

/**
 * All rights Reserved, Designed By www.pousheng.com
 *
 * @version V1.0
 * @Title: MonthMapperEnum
 * @Package com.pousheng.enums
 * @Description: 月份枚举类
 * @author: Geroge1226
 * @date: 2020-04-27 18:00
 * @Copyright: 2019 www.pousheng.cn Inc. All rights reserved.
 * 注意：本内容仅限于XXX内部传阅，禁止外泄以及用于其他的商业目
 */
public enum  MonthMapperEnum {

    JANUARY("01","Jan"),
    FEBRUARY("02","Feb"),
    MARCH("03","Mar"),
    APRIL("04","Apr"),
    MAY("05","May"),
    JUNE("06","Jun"),
    JULY("07","Jul"),
    AUGUST("08","Aug"),
    SEPTEMBER("09","Sep"),
    OCTOBER("10","Oct"),
    NOVEMBER("11","Nov"),
    DECEMBER("12","Dec");

    private String month;
    private String shorthand;

    MonthMapperEnum(String month, String shorthand) {
        this.month = month;
        this.shorthand = shorthand;
    }

    // 根据月份查询对应简写 
    public static String getShortHand(String month){
       for(MonthMapperEnum enu:MonthMapperEnum.values()){
           if(enu.getMonth().equals(month)){
               return enu.getShorthand();
           }
       }
       return null;
    }

    public String getMonth() {
        return month;
    }

    public void setMonth(String month) {
        this.month = month;
    }

    public String getShorthand() {
        return shorthand;
    }

    public void setShorthand(String shorthand) {
        this.shorthand = shorthand;
    }}

4、实现层

 public List<MonthInfoDTO> buildBannerMoth(Date date, Integer leftFactor, Integer rigthFator) {
        List<MonthInfoDTO> list = new ArrayList<>();
        // date时间左移量
        for(int i = leftFactor ;i<0;i++){
            String month = DateUtils.getMonths(date,i);
            MonthInfoDTO monthInfoDTO = wrapMonthInfo(month,i);
            list.add(monthInfoDTO);
        }
        // date时间右移量
        for(int j = 0; j<=rigthFator ; j++) {
            String month = DateUtils.getMonths(date,j);
            MonthInfoDTO monthInfoDTO = wrapMonthInfo(month,j);
            list.add(monthInfoDTO);
        }
        System.out.println(list);
        return list;
    }
 

 public MonthInfoDTO wrapMonthInfo(String month,Integer offet){
        MonthInfoDTO monthInfoDTO =  new MonthInfoDTO();
        monthInfoDTO.setShortand(MonthMapperEnum.getShortHand(month.split("-")[1]));
        monthInfoDTO.setMonth(month);
        monthInfoDTO.setOffset(offet);
        return monthInfoDTO;
    }

5、实体类

@Data
@ApiModel(description = "月份")
public class MonthInfoDTO {

    @ApiModelProperty(value = "月份：yyyy-MM")
    private String month;

    @ApiModelProperty(value = "偏移量,-5...0...5排序")
    private Integer offset;

    @ApiModelProperty(value = "英文月份简称")
    private String shortand;

}

注：以上关键方法参考网络，本次做实践记录，非优雅实现。

6、返回示例

{
  "code": "000000",
  "message": "Success",
  "result": [
    {
      "month": "2019-11",
      "offset": -5,
      "shortand": "Nov"
    },
    {
      "month": "2019-12",
      "offset": -4,
      "shortand": "Dec"
    },
    {
      "month": "2020-01",
      "offset": -3,
      "shortand": "Jan"
    },
    {
      "month": "2020-02",
      "offset": -2,
      "shortand": "Feb"
    },
    {
      "month": "2020-03",
      "offset": -1,
      "shortand": "Mar"
    },
    {
      "month": "2020-04",
      "offset": 0,
      "shortand": "Apr"
    },
    {
      "month": "2020-05",
      "offset": 1,
      "shortand": "May"
    },
    {
      "month": "2020-06",
      "offset": 2,
      "shortand": "Jun"
    },
    {
      "month": "2020-07",
      "offset": 3,
      "shortand": "Jul"
    },
    {
      "month": "2020-08",
      "offset": 4,
      "shortand": "Aug"
    },
    {
      "month": "2020-09",
      "offset": 5,
      "shortand": "Sep"
    }
  ]
}