学习笔记:关于时间

Date d1 = new Date();
logger.info("1<{}>", d1.getTime());                                                     // <1552463576744>
logger.info("2<{}>", new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(d1.getTime())); // <2019/03/13 15:52:56>
logger.info("3<{}>", new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(d1));           // <2019/03/13 15:52:56>

Date d2 = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").parse("1970/01/01 08:00:00");
logger.info("4<{}>", d2.getTime());                                                     // 结果 0
logger.info("5<{}>", new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(d2.getTime())); // <1970/01/01 08:00:00>

Date d3 = new SimpleDateFormat("yyyy/MM/dd").parse("2019/3/10");
d3 = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").parse("2019/3/10 22:36:01");
logger.info("6<{}>", d3);                                                               // <Sun Mar 10 22:36:01 CST 2019>
logger.info("d3 = <{}>", d3.getTime());                                                 // <1552228561000>
logger.info("d3= <{}>", new SimpleDateFormat("yyyy/MM/dd").format(d3.getTime()));       // <2019/03/10>

logger.info("7<{}>", DateUtil.getPatternDate("yyyy/MM/dd HH:mm:ss", 1552012596964L));   // <2019/03/08 10:36:36>
logger.info("8<{}>", DateUtil.getPatternDate("yyyy/MM/dd HH:mm:ss", 1551966731871L));   // <2019/03/07 21:52:11>

// 用"2018-11-28"算出"2018-11-21" 

String d = "2018-11-28";
String pattern1 = "yyyy-MM-dd";
String pattern2 = "yyyy-MM-dd HH:mm:ss";
SimpleDateFormat sdf1 = new SimpleDateFormat(pattern1);
SimpleDateFormat sdf2 = new SimpleDateFormat(pattern2);
int offset = -7;
long time = DateUtil.parseDateAddDaysToLongStrict(d, pattern1, offset);　　// 自定义工具 DateUtil
String day = DateUtil.getPatternDate(pattern1, time); 
logger.info("day:<{}>", day);

// 用今天时间,算出向前7天的日期,方法二

Calendar calendar = Calendar.getInstance();
logger.info("taday短格式:<{}>", sdf1.format(calendar.getTime()));    // 短格式
logger.info("taday长格式:<{}>", sdf2.format(calendar.getTime()));    // 长格式
calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) + offset);
Date tod = calendar.getTime();
String t = sdf1.format(tod);
logger.info("7天前的这一天:<{}>", t);

// 用Calendar根据时区获得当天00:00:00的时间戳

logger.info("当前时间戳:<{}>", System.currentTimeMillis());　 // 当前时间的时间戳
TimeZone curTimeZone = TimeZone.getTimeZone("GMT+8");    　　// 东8区
Calendar cal = Calendar.getInstance(curTimeZone);           // 当前时间, 精确到秒
long now = cal.getTimeInMillis();
logger.info("当前时间戳:<{}>", now);                      　　// 当前时间的时间戳

calendar.setTimeInMillis(now);
calendar.set(Calendar.HOUR_OF_DAY, 0);
calendar.set(Calendar.MINUTE, 0);
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
long dayBeginning = calendar.getTimeInMillis();
logger.info("当天开始时间戳:<{}>", dayBeginning);             // 今天00:00:00的时间戳
long dayEnd = dayBeginning + 86400000;
logger.info("当天结束时间戳:<{}>", dayEnd);                  // 第二天00:00:00的时间戳

学习笔记:关于时间

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