content: package com.java2nb.common.utils;
  
  import lombok.SneakyThrows;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.text.SimpleDateFormat;
  import java.util.ArrayList;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.List;
  
  /**
   * 日期处理
   */
  public class DateUtils {
      private final static Logger logger = LoggerFactory.getLogger(DateUtils.class);
      public final static String YEAR_PATTERN = "yyyy";
      public final static String MONTH_PATTERN = "MM";
      public final static String DAY_PATTERN = "dd";
      /**
       * 时间格式(yyyy-MM-dd)
       */
      public final static String DATE_PATTERN = "yyyy-MM-dd";
      /**
       * 时间格式(yyyy-MM-dd HH:mm:ss)
       */
      public final static String DATE_TIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
  
      public static String format(Date date) {
          return format(date, DATE_PATTERN);
      }
  
      public static String format(Date date, String pattern) {
          if (date != null) {
              SimpleDateFormat df = new SimpleDateFormat(pattern);
              return df.format(date);
          }
          return null;
      }
  
      /**
       * 计算距离现在多久，非精确
       *
       * @param date
       * @return
       */
      public static String getTimeBefore(Date date) {
          Date now = new Date();
          long l = now.getTime() - date.getTime();
          long day = l / (24 * 60 * 60 * 1000);
          long hour = (l / (60 * 60 * 1000) - day * 24);
          long min = ((l / (60 * 1000)) - day * 24 * 60 - hour * 60);
          long s = (l / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
          String r = "";
          if (day > 0) {
              r += day + "天";
          } else if (hour > 0) {
              r += hour + "小时";
          } else if (min > 0) {
              r += min + "分";
          } else if (s > 0) {
              r += s + "秒";
          }
          r += "前";
          return r;
      }
  
      /**
       * 计算距离现在多久，精确
       *
       * @param date
       * @return
       */
      public static String getTimeBeforeAccurate(Date date) {
          Date now = new Date();
          long l = now.getTime() - date.getTime();
          long day = l / (24 * 60 * 60 * 1000);
          long hour = (l / (60 * 60 * 1000) - day * 24);
          long min = ((l / (60 * 1000)) - day * 24 * 60 - hour * 60);
          long s = (l / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
          String r = "";
          if (day > 0) {
              r += day + "天";
          }
          if (hour > 0) {
              r += hour + "小时";
          }
          if (min > 0) {
              r += min + "分";
          }
          if (s > 0) {
              r += s + "秒";
          }
          r += "前";
          return r;
      }
  
      /**
       * 获取过去第几天的日期
       *
       * @param past
       * @return
       */
      @SneakyThrows
      public static String getPastDate(int past,Date date) {
          Calendar calendar = Calendar.getInstance();
          calendar.setTime(date);
          calendar.set(Calendar.DATE, calendar.get(Calendar.DATE) - past);
          Date today = calendar.getTime();
          SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
          return sdf.format(today);
      }
  
      /**
       * 获取过去几天的日期集合
       *
       * @param past
       * @return
       */
      public static List<String> getDateList(int past,Date date) {
          List<String> result = new ArrayList<>(past);
          for(int i = past - 1 ; i > 0 ; i--){
              result.add(getPastDate(i,date));
          }
          //今天的日期
          result.add(new SimpleDateFormat("yyyy-MM-dd").format(date));
          return result;
  
      }
  }
  