近期一直做的几个功能都跟日期处理有关。比方推断今天是否登录。今天的最小时间。今天结束的最大时间等。

代码中都是用的JDK自带的 Calendar，使用起来相当费劲了，于是乎，忍不了，找到了一个名叫：JodaTime 的库，

眼下Joda Time 已经纳入 JDK 8 的官方API了，可是JDK 8还是非常遥远。以下我给大家演示几个实例：

1、  获取今天的開始时间：比方：2014-06-19 00:00:00

Joda Time

JDK

DateTime nowTime = new DateTime();

DateTime startOfDay =  nowTime.withTimeAtStartOfDay();

Calendar c1 = Calendar.getInstance();

c1.setTimeInMillis(timeInMs);

c1.set(Calendar.HOUR_OF_DAY, 0);

c1.set(Calendar.MINUTE, 0);

c1.set(Calendar.SECOND, 0);

c1.set(Calendar.MILLISECOND, 0);

return c1.getTimeInMillis();

2、  获取今天的结束时间：比方：2014-06-19 23:59:59

Joda Time

JDK

DateTime nowTime = new DateTime();

DateTime endOfDay =  nowTime.millisOfDay().withMaximumValue();

Calendar c1 = Calendar.getInstance();

c1.setTimeInMillis(timeInMs);

c1.set(Calendar.HOUR_OF_DAY, 23);

c1.set(Calendar.MINUTE, 59);

c1.set(Calendar.SECOND, 59);

c1.set(Calendar.MILLISECOND, 0);

return c1.getTimeInMillis();

3、  获取如今距离今天结束还有多长时间

DateTimenowTime = new DateTime();

DateTime endOfDay = nowTime.millisOfDay().withMaximumValue();

endOfDay.getMillis()-nowTime.getMillis()

4、  计算两个日期的相隔天数

Joda Time

JDK

DateTime nowTime = new DateTime();

DateTime futureTime = new DateTime(2015, 10, 1, 0, 0, 0);

Int days = Days.daysBetween(nowTime, futureTime).getDays();

(实现不是非常好)

public static int getBetweenDay(long startTime,

long endTime) {

Calendar start = Calendar.getInstance();

start.setTimeInMillis(startTime);

Calendar end = Calendar.getInstance();

end.setTimeInMillis(endTime);

return (int) ((end.getTimeInMillis() - start.getTimeInMillis()) / 86400000);

}

还有非常多比較方便的功能，能够自己去尝试。

Maven 仓库：

joda-time

joda-time

2.3