时间戳转化

1.时间戳转换为date

    /**
     * long 转换为data   
      * @Param time 格式一定为yyyy-MM-dd
     */
    public static String longToDate(Long time) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Date dt = new Date(time);
        String stime = sdf.format(dt);
        return stime;

    }

1.1时间戳转换为date

    public static String getTime(long time){      //年  月 日  时 分 秒
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
       return sdf.format(System.currentTimeMillis()); //获取当前时间戳
    }

2.date转换为时间戳

  /**
     * date 转换为long  
      * @Param time 格式一定为yyyy-MM-dd
     */
  public static Long dateToLong(String time) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
          Date choice = sdf.parse(time);
          Long time = choice.getTime();
          return time;

    }

3.日期与日期比较

try {
                    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");//切记两个时间比较格式一定要相同
                    Date choice = dateFormat.parse("2019-09-06");//选择时间
                    Date current = 
                       dateFormat.parse("2019-09-08");//当前时间
                    long  min = choice.getTime()-current.getTime();
                     if(min>0){
                          选择时间晚于当前时间
                   }else{
     选择时间早于当前时间
                   }
                  } catch (Exception e) {
                    e.printStackTrace();
                }

4.获取前一个月的日期

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");// HH:mm:ss
        Calendar calendar = Calendar.getInstance();
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH)-30);
        Date date1   = calendar.getTime();
        startl=date1.getTime();
        starttime.setText(simpleDateFormat.format(date1));
        kaishishijian = simpleDateFormat.format(date1);

5.获取当前时间

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");// HH:mm:ss
 Date date = new Date(System.currentTimeMillis());
        endtime.setText(simpleDateFormat.format(date));
  endl=date.getTime();

6.获取上一个月第一天和上一个月最后一天

//设置初始时间
    public void initTime() {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");// HH:mm:ss
        //获取前一个月第一天
        Calendar calendar1 = Calendar.getInstance();
        calendar1.add(Calendar.MONTH, -1);
        calendar1.set(Calendar.DAY_OF_MONTH,1);
        String firstDay = simpleDateFormat.format(calendar1.getTime());
        startl = calendar1.getTime().getTime();
        //  starttime.setText(currentyear + "-" + month + "-" + "01");
        starttime.setText(firstDay);
        //获取前一个月最后一天
        Calendar calendar2 = Calendar.getInstance();
        calendar2.set(Calendar.DAY_OF_MONTH, 0);
        String lastDay = simpleDateFormat.format(calendar2.getTime());
        endl = calendar2.getTime().getTime();
        endtime.setText(lastDay);

      /*  Calendar ca1 = Calendar.getInstance();
        ca1.set(Calendar.DAY_OF_MONTH, ca1.getActualMinimum(Calendar.DAY_OF_MONTH));
        String start = simpleDateFormat.format(ca1.getTime());
        startl = ca1.getTime().getTime();
        //  starttime.setText(currentyear + "-" + month + "-" + "01");
        starttime.setText(start);
//获取当前时间
        Calendar ca = Calendar.getInstance();
        ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));
        String last = simpleDateFormat.format(ca.getTime());
        endl = ca.getTime().getTime();
        endtime.setText(last);
*/
    }