获取前（后）x月的日期

package com.jesims.busresume.web;

import org.springframework.stereotype.Service;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;

@Service
public class RiskControlRulesDateUtils {
    private static final DateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd");

    /**
     * 获取前x月的日期
     * @param month
     * @return
     */
    public  Map<String,String> getNowAndBefore(int month){
        Date now = new Date();
        Date newDate = stepMonth(now, -month);
        Map<String,String> map =new HashMap<>();
        // 现在时间
        map.put("now",DATE_FORMAT.format(now));
        // 之前时间
        map.put("before",DATE_FORMAT.format(newDate));
        return map;
    }

    /**
     * 获取后x天的日期
     * @param day
     * @return
     */
    public  Map<String,String> getNowAndChangeDay(int day){
        Date now = new Date();
        Date newDate = stepDay(now, day);
        Map<String,String> map =new HashMap<>();
        // 现在时间
        map.put("now",DATE_FORMAT.format(now));
        // 之后时间
        map.put("change",DATE_FORMAT.format(newDate));
        return map;
    }

    /**
     * 在给定的日期加上或减去指定月份后的日期
     * @param sourceDate 原始时间
     * @param month      要调整的月份，向前为负数，向后为正数
     * @return
     */
    public  Date stepMonth(Date sourceDate, int month) {
        Calendar c = Calendar.getInstance();
        c.setTime(sourceDate);
        c.add(Calendar.MONTH, month);
        return c.getTime();
    }
    /**
     * 在给定的日期加上或减去指定月份后的日期
     * @param
     * @param day      要调整的天数，向前为负数，向后为正数
     * @return
     */
    public  Date stepDay(Date sourceDate, int day) {
        Calendar c = Calendar.getInstance();
        c.setTime(sourceDate);
        c.add(Calendar.DAY_OF_MONTH, day);
        return c.getTime();
    }

    /**
     * 输出如下：
     * "[2016-02, 2016-03, 2016-04, 2016-05, 2016-06, 2016-07,
     * 2016-08, 2016-09, 2016-10, 2016-11, 2016-12, 2017-01]"
     */
    /**
     * 获取当前系统时间最近12月的年月（含当月）
     * @return
     */
    public  String[] getLatest12Month(){
        String[] latest12Months = new String[12];
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.MONTH, cal.get(Calendar.MONTH)+1); //要先+1,才能把本月的算进去
        for(int i=0; i<12; i++){
            cal.set(Calendar.MONTH, cal.get(Calendar.MONTH)-1); //逐次往前推1个月
            latest12Months[11-i] = cal.get(Calendar.YEAR)+ "-" +fillZero(cal.get(Calendar.MONTH)+1);
        }
        System.out.println(Arrays.toString(latest12Months));

        return latest12Months;
    }
    public  List<String> getLast12Month(){
        List<String> list =new ArrayList<>();
        String[] latest12Month = getLatest12Month();
        for (int i = 0; i < latest12Month.length; i++) {
            list.add(latest12Month[i]);
        }
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }

        return  list;
    }

    /**
     * 格式化月份
     */
    public static String fillZero(int i){
        String month = "";
        if(i<10){
            month = "0" + i;
        }else{
            month = String.valueOf(i);
        }
        return month;
    }
}