Java 时间格式处理
jdk里面的日期格式处理使用SimpleDateFormat,这个类其实也是在内部调用的Calendar
Calendar概念比较负责，涉及到时区和本地化
看一些简单的demo:
package com.qhong; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class Main { public static void main(String[] args) throws Exception { DateFormat df=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS"); System.out.println(df.format(new Date())); Calendar calendar=Calendar.getInstance(); Date dt=calendar.getTime(); System.out.println(df.format(dt)); System.out.println(calendar.getWeekYear()); System.out.println(calendar.getFirstDayOfWeek()); System.out.println(calendar.getWeeksInWeekYear()); System.out.println("===================="); System.out.println(calendar.get(Calendar.YEAR)); System.out.println(calendar.get(Calendar.MONTH)); System.out.println(calendar.get(Calendar.DAY_OF_MONTH)); System.out.println(calendar.get(Calendar.DAY_OF_WEEK)); System.out.println(calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH)); System.out.println(calendar.get(Calendar.DAY_OF_YEAR)); System.out.println("===================="); System.out.println(calendar.get(Calendar.DATE)); System.out.println(calendar.get(Calendar.HOUR)); System.out.println(calendar.get(Calendar.HOUR_OF_DAY)); System.out.println(calendar.get(Calendar.MINUTE)); System.out.println(calendar.get(Calendar.SECOND)); System.out.println("===================="); System.out.println(calendar.get(Calendar.MILLISECOND)); Calendar NewCalendar=Calendar.getInstance(); NewCalendar.setTime(new Date()); System.out.println(df.format(NewCalendar.getTime())); NewCalendar.add(Calendar.YEAR,-1); System.out.println(df.format(NewCalendar.getTime())); NewCalendar.add(Calendar.MONTH,2); System.out.println(df.format(NewCalendar.getTime())); NewCalendar.add(Calendar.DATE,3); //后者大，显示 -1 System.out.println(df.format(NewCalendar.getTime())); System.out.println("时间比较："+NewCalendar.compareTo(calendar)); //前者大，显示 1 NewCalendar.add(Calendar.YEAR,1); System.out.println("时间比较："+NewCalendar.compareTo(calendar)); } }
2017-03-13 22:36:08:393 2017-03-13 22:36:08:394 2017 1 52 ==================== 2017 2 13 2 2 72 ==================== 13 10 22 36 8 ==================== 394 2017-03-13 22:36:08:394 2016-03-13 22:36:08:394 2016-05-13 22:36:08:394 2016-05-16 22:36:08:394 时间比较：-1 时间比较：1
比较好的第三方解决方案：joda-time
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>2.9.9</version>
</dependency>
最简单的demo:
package com.qhong; import org.joda.time.DateTime; import org.joda.time.format.DateTimeFormat; import org.joda.time.format.DateTimeFormatter; import java.util.Date; public class Main { public static void main(String[] args) { Date now=new Date(); DateTime dt=new DateTime(now); System.out.println(dt.toString("yyyy-MM-dd HH:mm:ss")); String str="2017-08-15 12:12:22"; DateTimeFormatter format = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss"); DateTime dt2=format.parseDateTime(str); DateTime dt3=DateTime.parse(str,format); System.out.println(dt2.equals(dt3)); System.out.println(dt2.toString("yyyy-MM-dd HH:mm:ss")); } }
Output:
2017-08-06 22:14:15
true
2017-08-15 12:12:22
复杂的demo:
package com.qhong; import org.joda.time.DateTime; import org.joda.time.Days; import org.joda.time.LocalDate; import org.joda.time.format.DateTimeFormat; import org.joda.time.format.DateTimeFormatter; import java.util.Calendar; import java.util.Date; import java.util.Locale; public class Main { public static void main(String[] args) { //初始化时间 DateTime dateTime=new DateTime(2017, 8, 6, 20, 34,55); //下面就是按照一点的格式输出时间 String str2 = dateTime.toString("MM/dd/yyyy hh:mm:ss.SSSa"); String str3 = dateTime.toString("dd-MM-yyyy HH:mm:ss"); String str4 = dateTime.toString("EEEE dd MMMM, yyyy HH:mm:ssa"); String str5 = dateTime.toString("MM/dd/yyyy HH:mm ZZZZ"); String str6 = dateTime.toString("MM/dd/yyyy HH:mm Z"); System.out.println(str2); System.out.println(str3); System.out.println(str4); System.out.println(str5); System.out.println(str6); System.out.println(dateTime.toString("yyyy-MM-dd HH:mm:ss")); System.out.println("=========================="); DateTimeFormatter format = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss"); //时间解析 DateTime dateTime2 = DateTime.parse("2012-12-21 23:22:45", format); //时间格式化，输出==> 2012/12/21 23:22:45 Fri String string_u = dateTime2.toString("yyyy/MM/dd HH:mm:ss EE"); System.out.println(string_u); //格式化带Locale，输出==> 2012年12月21日 23:22:45 星期五 String string_c = dateTime2.toString("yyyy年MM月dd日 HH:mm:ss EE", Locale.CHINESE); System.out.println(string_c); DateTime dt1 = new DateTime();// 取得当前时间 // 根据指定格式,将时间字符串转换成DateTime对象,这里的格式和上面的输出格式是一样的 DateTime dt2 = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss").parseDateTime("2012-12-26 03:27:39"); //计算两个日期间隔的天数 LocalDate start=new LocalDate(2012, 12,14); LocalDate end=new LocalDate(2013, 01, 15); int days = Days.daysBetween(start, end).getDays(); //计算两个日期间隔的小时数,分钟数,秒数 //增加日期 DateTime dateTime1 = DateTime.parse("2012-12-03"); dateTime1 = dateTime1.plusDays(30); dateTime1 = dateTime1.plusHours(3); dateTime1 = dateTime1.plusMinutes(3); dateTime1 = dateTime1.plusMonths(2); dateTime1 = dateTime1.plusSeconds(4); dateTime1 = dateTime1.plusWeeks(5); dateTime1 = dateTime1.plusYears(3); // Joda-time 各种操作..... dateTime = dateTime.plusDays(1) // 增加天 .plusYears(1)// 增加年 .plusMonths(1)// 增加月 .plusWeeks(1)// 增加星期 .minusMillis(1)// 减分钟 .minusHours(1)// 减小时 .minusSeconds(1);// 减秒数 //判断是否闰月 DateTime dt4 = new DateTime(); org.joda.time.DateTime.Property month = dt4.monthOfYear(); System.out.println("是否闰月:" + month.isLeap()); //取得 3秒前的时间 DateTime dt5 = dateTime1.secondOfMinute().addToCopy(-3); dateTime1.getSecondOfMinute();// 得到整分钟后，过的秒钟数 dateTime1.getSecondOfDay();// 得到整天后，过的秒钟数 dateTime1.secondOfMinute();// 得到分钟对象,例如做闰年判断等使用 // DateTime与java.util.Date对象,当前系统TimeMillis转换 DateTime dt6 = new DateTime(new Date()); Date date = dateTime1.toDate(); DateTime dt7 = new DateTime(System.currentTimeMillis()); dateTime1.getMillis(); Calendar calendar = Calendar.getInstance(); dateTime = new DateTime(calendar); } }
Output:
08/06/2017 08:34:55.000下午 06-08-2017 20:34:55 星期日 06 八月, 2017 20:34:55下午 08/06/2017 20:34 Asia/Shanghai 08/06/2017 20:34 +0800 2017-08-06 20:34:55 ========================== 2012/12/21 23:22:45 星期五 2012年12月21日 23:22:45 星期五 是否闰月:false
比SimpleDataFormat简单多了
http://blog.csdn.net/joyous/article/details/9630893
http://sunnyhl.iteye.com/blog/1205820
http://www.cnblogs.com/peida/archive/2013/05/31/3070790.html
