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java当前时间获取
2020-01-16 21:11:29接着源码阅读:new Date之旅,补充几种关于获取当前时间的方式。 Date 在Java中,获取当前日期最简单的方法之一就是直接实例化位于Java包java.util的Date类。 Date date = new Date(); System.currentTimeMillis ...前言
接着源码阅读:new Date之旅,补充几种关于获取当前时间的方式。
Date
在Java中,获取当前日期最简单的方法之一就是直接实例化位于Java包java.util的Date类。
Date date = new Date();
System.currentTimeMillis
获取标准时间可以通过System.currentTimeMillis()方法获取,此方法不受时区影响,得到的结果是时间戳格式的。
long time = System.currentTimeMillis();
源码:
/** * Returns the current time in milliseconds. Note that * while the unit of time of the return value is a millisecond, * the granularity of the value depends on the underlying * operating system and may be larger. For example, many * operating systems measure time in units of tens of * milliseconds. * * <p> See the description of the class <code>Date</code> for * a discussion of slight discrepancies that may arise between * "computer time" and coordinated universal time (UTC). * * @return the difference, measured in milliseconds, between * the current time and midnight, January 1, 1970 UTC. * @see java.util.Date */ public static native long currentTimeMillis();
Calendar
Calendar类,专门用于转换特定时刻和日历字段之间的日期和时间。
Calendar calendar = Calendar.getInstance();
源码:
/** * Gets a calendar using the default time zone and locale. The * <code>Calendar</code> returned is based on the current time * in the default time zone with the default * {@link Locale.Category#FORMAT FORMAT} locale. * * @return a Calendar. */ public static Calendar getInstance() { return createCalendar(TimeZone.getDefault(), Locale.getDefault(Locale.Category.FORMAT)); } private static Calendar createCalendar(TimeZone zone, Locale aLocale) { CalendarProvider provider = LocaleProviderAdapter.getAdapter(CalendarProvider.class, aLocale) .getCalendarProvider(); if (provider != null) { try { return provider.getInstance(zone, aLocale); } catch (IllegalArgumentException iae) { // fall back to the default instantiation } } Calendar cal = null; if (aLocale.hasExtensions()) { String caltype = aLocale.getUnicodeLocaleType("ca"); if (caltype != null) { switch (caltype) { case "buddhist": cal = new BuddhistCalendar(zone, aLocale); break; case "japanese": cal = new JapaneseImperialCalendar(zone, aLocale); break; case "gregory": cal = new GregorianCalendar(zone, aLocale); break; } } } if (cal == null) { // If no known calendar type is explicitly specified, // perform the traditional way to create a Calendar: // create a BuddhistCalendar for th_TH locale, // a JapaneseImperialCalendar for ja_JP_JP locale, or // a GregorianCalendar for any other locales. // NOTE: The language, country and variant strings are interned. if (aLocale.getLanguage() == "th" && aLocale.getCountry() == "TH") { cal = new BuddhistCalendar(zone, aLocale); } else if (aLocale.getVariant() == "JP" && aLocale.getLanguage() == "ja" && aLocale.getCountry() == "JP") { cal = new JapaneseImperialCalendar(zone, aLocale); } else { cal = new GregorianCalendar(zone, aLocale); } } return cal; }
LocalDateTime
LocalDateTime,是Java中最常用的Date / Time类,代表前两个类的组合 – 即日期和时间的值。
LocalDateTime dateTime = LocalDateTime.now();
源码:
/** * Obtains the current date-time from the system clock in the default time-zone. * <p> * This will query the {@link Clock#systemDefaultZone() system clock} in the default * time-zone to obtain the current date-time. * <p> * Using this method will prevent the ability to use an alternate clock for testing * because the clock is hard-coded. * * @return the current date-time using the system clock and default time-zone, not null */ public static LocalDateTime now() { return now(Clock.systemDefaultZone()); } /** * Obtains the current date-time from the specified clock. * <p> * This will query the specified clock to obtain the current date-time. * Using this method allows the use of an alternate clock for testing. * The alternate clock may be introduced using {@link Clock dependency injection}. * * @param clock the clock to use, not null * @return the current date-time, not null */ public static LocalDateTime now(Clock clock) { Objects.requireNonNull(clock, "clock"); final Instant now = clock.instant(); // called once ZoneOffset offset = clock.getZone().getRules().getOffset(now); return ofEpochSecond(now.getEpochSecond(), now.getNano(), offset); } /** * Obtains an instance of {@code LocalDateTime} using seconds from the * epoch of 1970-01-01T00:00:00Z. * <p> * This allows the {@link ChronoField#INSTANT_SECONDS epoch-second} field * to be converted to a local date-time. This is primarily intended for * low-level conversions rather than general application usage. * * @param epochSecond the number of seconds from the epoch of 1970-01-01T00:00:00Z * @param nanoOfSecond the nanosecond within the second, from 0 to 999,999,999 * @param offset the zone offset, not null * @return the local date-time, not null * @throws DateTimeException if the result exceeds the supported range, * or if the nano-of-second is invalid */ public static LocalDateTime ofEpochSecond(long epochSecond, int nanoOfSecond, ZoneOffset offset) { Objects.requireNonNull(offset, "offset"); NANO_OF_SECOND.checkValidValue(nanoOfSecond); long localSecond = epochSecond + offset.getTotalSeconds(); // overflow caught later long localEpochDay = Math.floorDiv(localSecond, SECONDS_PER_DAY); int secsOfDay = (int)Math.floorMod(localSecond, SECONDS_PER_DAY); LocalDate date = LocalDate.ofEpochDay(localEpochDay); LocalTime time = LocalTime.ofNanoOfDay(secsOfDay * NANOS_PER_SECOND + nanoOfSecond); return new LocalDateTime(date, time); }
结果
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Java 当前时间的上一个月时间、上一年时间
2020-07-30 19:34:18Java 当前时间的上一个月时间、上一年时间 获取当前时间 /** * 获取当前时间 * @return Timestamp * @author zhangyao * date: 2018/8/22 11:36 */ public static Timestamp now() { return new Timestamp...Java 当前时间的上一个月时间、上一年时间
- 获取当前时间
/** * 获取当前时间 * @return Timestamp * @author zhangyao * date: 2018/8/22 11:36 */ public static Timestamp now() { return new Timestamp(Calendar.getInstance().getTimeInMillis()); }
- 上个月、上一年;time可以用获取当前时间的值
/** * 上一个月 */ private Timestamp lastMonthTime(Timestamp time){ Calendar c = Calendar.getInstance(); c.setTime(time); c.add(Calendar.MONTH, -1); return new Timestamp(c.getTimeInMillis()); } private Timestamp lastYearTime(Timestamp time){ //过去一年 Calendar c = Calendar.getInstance(); c.setTime(time); c.add(Calendar.YEAR, -1); return new Timestamp(c.getTimeInMillis()); }
- 获取当前时间
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java当前时间增加一小时怎么写
2020-06-02 10:54:28获取java当前时间增加一小时怎么写 首先新建Date对象,然后转化成Calendar对象,利用其中的方法得到一小时后的Calendar对象,再转化成Date。 //设置创建时间 Date creatTime = new Date(); noteEatlyWarningInfo...获取java当前时间增加一小时怎么写
首先新建Date对象,然后转化成Calendar对象,利用其中的方法得到一小时后的Calendar对象,再转化成Date。
//设置创建时间 Date creatTime = new Date(); noteEatlyWarningInfo.setCreatTime(creatTime); //设置生效时间为一小时后 Calendar cal = Calendar.getInstance(); cal.setTime(creatTime); cal.add(Calendar.HOUR, 1);// 24小时制 Date effectivetime = cal.getTime(); noteEatlyWarningInfo.setEffectiveTime(effectivetime);
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java当前时间转化毫秒_java 获取当前时间精确到毫秒 格式化
2020-12-21 00:43:42方法1:new SimpleDateFormat(“yyyyMMddHHmmssSSS”) .format(new Date() );方法2:new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss:... 获取当前系统时间和日期并格式化输出:import java.util.Date;import java.text....方法1:new SimpleDateFormat(“yyyyMMddHHmmssSSS”) .format(new Date() );
方法2:new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss:SSS”) .format(new Date() );
一. 获取当前系统时间和日期并格式化输出:
import java.util.Date;
import java.text.SimpleDateFormat;
public class NowString {
public static void main(String[] args) {
SimpleDateFormat df = new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss”);//设置日期格式
System.out.println(df.format(new Date()));// new Date()为获取当前系统时间
}
}
二. 在数据库里的日期只以年-月-日的方式输出,可以用下面两种方法:
1、用convert()转化函数:
String sqlst = “select convert(varchar(10),bookDate,126) as convertBookDate from roomBook where bookDate between ’2007-4-10′ and ’2007-4-25′”;
System.out.println(rs.getString(“convertBookDate”));
2、利用SimpleDateFormat类:
先要输入两个java包:
import java.util.Date;
import java.text.SimpleDateFormat;
然后:
定义日期格式:SimpleDateFormat sdf = new SimpleDateFormat(yy-MM-dd);
sql语句为:String sqlStr = “select bookDate from roomBook where bookDate between ’2007-4-10′ and ’2007-4-25′”;
输出:
System.out.println(df.format(rs.getDate(“bookDate”)));
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java中获取当前日期和时间的方法
import java.util.Date;
import java.util.Calendar;
import java.text.SimpleDateFormat;
public class TestDate{
public static void main(String[] args){
Date now = new Date();
SimpleDateFormat dateFormat = new SimpleDateFormat(“yyyy/MM/dd HH:mm:ss”);//可以方便地修改日期格式
String hehe = dateFormat.format( now );
System.out.println(hehe);
Calendar c = Calendar.getInstance();//可以对每个时间域单独修改
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int date = c.get(Calendar.DATE);
int hour = c.get(Calendar.HOUR_OF_DAY);
int minute = c.get(Calendar.MINUTE);
int second = c.get(Calendar.SECOND);
System.out.println(year + “/” + month + “/” + date + ” ” +hour + “:” +minute + “:” + second);
}
}
有时候要把String类型的时间转换为Date类型,通过以下的方式,就可以将你刚得到的时间字符串转换为Date类型了。
SimpleDateFormat sdf=new SimpleDateFormat(“yyyy-MM-dd”);
java.util.Date time=null;
try {
time= sdf.parse(sdf.format(new Date()));
} catch (ParseException e) {
e.printStackTrace();
}
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2019-01-26 17:05:00System.out.println("加了一个月之后,广告到期时间为:" + df.format(newDate)); } public static Date stepMonth(Date sourceDate, int month) { Calendar c = Calendar.getInstance(); c.setTime(sourceDate);... -
java 当前时间 long_java获取当前时间戳的方法
2021-02-12 18:38:58转发来源: ...utm_medium=referral获取当前时间戳//方法 一System.currentTimeMillis();//方法 二Calendar.getInstance().getTimeInMillis();//方法 三new Date().... -
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2015-12-09 15:15:46import java.util.Calendar; import java.util.Date; public class DateAddOne { ... * 设置当前时间加1 */ public static void main(String[] args) { Calendar c = Calendar.getInstance(); -
java 30分钟_java 当前时间加减30分钟的时间
2021-02-12 16:39:04如代码所示:SimpleDateFormatsdf=newSimpleDateFormat("yyyy-MM-ddHH:mm:ss");...System.out.println("当前时间:"+sdf.format(now));方法一:longtime=30*60*1000;//30分钟DateafterDate=newDate(... -
Java 当前时间 转换成 农历(阴历)时间
2017-12-04 14:08:10文章转自 : http://www.it610.com/article/271380.htm 亲测可用 . ....import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Dat -
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2021-02-12 19:21:52String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";... //当前时间Date dBefore = new Date();Calendar calendar = Calendar.getInsta... -
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2021-02-26 18:56:35SimpleDateFormat formatter = new SimpleDateFormat( "yyyy.MM.dd HH:mm:ss a ZZZ ");String LgTime = formatter.format(LoginDate1);结果为24小时:星期四 2005.07.14 11:07:812 上午 +0800定... -
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