使用SimpleDateFormat来实现格式化日期
import java.text.SimpleDateFormat; import java.util.Date; public class DateFormatExample { public static void main(String args[]) { Date today = new Date(); System.out.println("今天 is : " + today); SimpleDateFormat DATE_FORMAT = new SimpleDateFormat("dd-MM-yyyy"); String date = DATE_FORMAT.format(today); System.out.println("今天 in dd-MM-yyyy format : " + date); DATE_FORMAT = new SimpleDateFormat("dd/MM/yy"); date = DATE_FORMAT.format(today); System.out.println("今天 in dd/MM/yy pattern : " + date); //formatting Date with time information DATE_FORMAT = new SimpleDateFormat("dd-MM-yy:HH:mm:SS"); date = DATE_FORMAT.format(today); System.out.println("今天 in dd-MM-yy:HH:mm:SS : " + date); //SimpleDateFormat example - Date with timezone information DATE_FORMAT = new SimpleDateFormat("dd-MM-yy:HH:mm:SS Z"); date = DATE_FORMAT.format(today); System.out.println("今天 in dd-MM-yy:HH:mm:SSZ : " + date); } }
但是
DateFormat 的所有实现,包括 SimpleDateFormat 都不是线程安全的,因此你不应该在多线程序中使用,除非是在对外线程安全的环境中使用,如 将 SimpleDateFormat 限制在 ThreadLocal 中。如果你不这么做,在解析或者格式化日期的时候,可能会获取到一个不正确的结果。因此,从日期、时间处理的所有实践来说,我强力推荐 joda-time 库。
Joda-Time
主要的特点包括:
1. 易于使用:Calendar让获取"正常的"的日期变得很困难,使它没办法提供简单的方法,而Joda-Time能够 直接进行访问域并且索引值1就是代表January。
2. 易于扩展:JDK支持多日历系统是通过Calendar的子类来实现,这样就显示的非常笨重而且事实 上要实现其它日历系统是很困难的。Joda-Time支持多日历系统是通过基于Chronology类的插件体系来实现。
3. 提供一组完整的功能:它打算提供 所有关系到date-time计算的功能.Joda-Time当前支持8种日历系统,而且在将来还会继续添加,有着比JDK Calendar更好的整体性能等等。
封装joda-time的时间工具类:
import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import java.util.HashMap; import java.util.Map; import java.util.TimeZone; import org.joda.time.DateTime; import org.joda.time.DateTimeConstants; import org.joda.time.DateTimeZone; import org.joda.time.Days; import org.joda.time.LocalDate; import com.sun.istack.internal.Nullable; /** * 使用joda的时间工具类 * @author soyoungboy * */ public class DateUtils { public static final long SECOND = 1000; // 1秒 java已毫秒为单位 public static final long MINUTE = SECOND * 60; // 一分钟 public static final long HOUR = MINUTE * 60; // 一小时 public static final long DAY = HOUR * 24; // 一天 public static final long WEEK = DAY * 7; // 一周 public static final long YEAR = DAY * 365; // 一年 public static final String FORMAT_TIME = "yyyy-MM-dd HH:mm:ss"; // 默认时间格式 public static final String FORMAT_TIME_MINUTE = "yyyy-MM-dd HH:mm"; // 默认时间格式 public static final String FORTER_DATE = "yyyy-MM-dd"; // 默认日期格式 private static final Map<Integer, String> WEEK_DAY = new HashMap<Integer, String>(); static { WEEK_DAY.put(7, "星期六"); WEEK_DAY.put(1, "星期天"); WEEK_DAY.put(2, "星期一"); WEEK_DAY.put(3, "星期二"); WEEK_DAY.put(4, "星期三"); WEEK_DAY.put(5, "星期四"); WEEK_DAY.put(6, "星期五"); } /** * 获取当前系统时间 * * @return yyyy-MM-dd HH:mm:ss */ public static String getCurrentTime() { DateTime dt = new DateTime(); String time = dt.toString(FORMAT_TIME); return time; } /** * 获取系统当前时间按照指定格式返回 * * @param pattern * yyyy/MM/dd hh:mm:a * @return */ public static String getCurrentTimePattern(String pattern) { DateTime dt = new DateTime(); String time = dt.toString(pattern); return time; } /** * 获取当前日期 * * @return */ public static String getCurrentDate() { DateTime dt = new DateTime(); String date = dt.toString(FORTER_DATE); return date; } /** * 获取当前日期按照指定格式 * * @param pattern * @return */ public static String getCurrentDatePattern(String pattern) { DateTime dt = new DateTime(); String date = dt.toString(pattern); return date; } /** * 按照时区转换时间 * * @param date * @param timeZone * 时区 * @param parrten * @return */ @Nullable public static String format(Date date, TimeZone timeZone, String parrten) { if (date == null) { return null; } SimpleDateFormat sdf = new SimpleDateFormat(parrten); sdf.setTimeZone(timeZone); return sdf.format(date); } /** * 获取指定时间 * * @param year * 年 * @param month * 月 * @param day * 天 * @param hour * 小时 * @param minute * 分钟 * @param seconds * 秒 * @return yyyy-MM-dd HH:mm:ss */ public static String getPointTime(Integer year, Integer month, Integer day, Integer hour, Integer minute, Integer seconds) { DateTime dt = new DateTime(year, month, day, hour, minute, seconds); String date = dt.toString(FORMAT_TIME); return date; } /** * * @param year * 年 * @param month * 月 * @param day * 天 * @param hour * 小时 * @param minute * 分钟 * @param seconds * 秒 * @param parrten * 自定义格式 * @return parrten */ public static String getPointTimePattern(Integer year, Integer month, Integer day, Integer hour, Integer minute, Integer seconds, String parrten) { DateTime dt = new DateTime(year, month, day, hour, minute, seconds); String date = dt.toString(parrten); return date; } /** * 获取指定日期 * * @param year * @param month * @param day * @return */ public static String getPointDate(Integer year, Integer month, Integer day) { LocalDate dt = new LocalDate(year, month, day); String date = dt.toString(FORTER_DATE); return date; } /** * 获取指定日期 返回指定格式 * * @param year * @param month * @param day * @param parrten * @return */ public static String getPointDatParrten(Integer year, Integer month, Integer day, String parrten) { LocalDate dt = new LocalDate(year, month, day); String date = dt.toString(parrten); return date; } /** * 获取当前是一周星期几 * * @return */ public static String getWeek() { DateTime dts = new DateTime(); String week = null; switch (dts.getDayOfWeek()) { case DateTimeConstants.SUNDAY: week = "星期日"; break; case DateTimeConstants.MONDAY: week = "星期一"; break; case DateTimeConstants.TUESDAY: week = "星期二"; break; case DateTimeConstants.WEDNESDAY: week = "星期三"; break; case DateTimeConstants.THURSDAY: week = "星期四"; break; case DateTimeConstants.FRIDAY: week = "星期五"; break; case DateTimeConstants.SATURDAY: week = "星期六"; default: break; } return week; } /** * 获取指定时间是一周的星期几 * * @param year * @param month * @param day * @return */ public static String getWeekPoint(Integer year, Integer month, Integer day) { LocalDate dts = new LocalDate(year, month, day); String week = null; switch (dts.getDayOfWeek()) { case DateTimeConstants.SUNDAY: week = "星期日"; break; case DateTimeConstants.MONDAY: week = "星期一"; break; case DateTimeConstants.TUESDAY: week = "星期二"; break; case DateTimeConstants.WEDNESDAY: week = "星期三"; break; case DateTimeConstants.THURSDAY: week = "星期四"; break; case DateTimeConstants.FRIDAY: week = "星期五"; break; case DateTimeConstants.SATURDAY: week = "星期六"; break; default: break; } return week; } /** * 格式化日期 * * @param date * @return yyyy-MM-dd HH:mm:ss */ @Nullable public static String format(Date date) { if (date == null) { return null; } SimpleDateFormat format = new SimpleDateFormat(FORMAT_TIME); return format.format(date); } /** * 格式化日期字符串 * * @param date * 日期 * @param pattern * 日期格式 * @return */ @Nullable public static String format(Date date, String pattern) { if (date == null) { return null; } SimpleDateFormat format = new SimpleDateFormat(pattern); return format.format(date); } /** * 解析日期 * * @param date * 日期字符串 * @param pattern * 日期格式 * @return */ @Nullable public static Date parse(String date, String pattern) { if (date == null) { return null; } Date resultDate = null; try { resultDate = new SimpleDateFormat(pattern).parse(date); } catch (ParseException e) { } return resultDate; } /** * 解析日期yyyy-MM-dd HH:mm:ss * * @param date * 日期字符串 * @return */ @Nullable public static Date parse(String date) { if (date == null) { return null; } try { return new SimpleDateFormat(FORMAT_TIME).parse(date); } catch (ParseException e) { return null; } } /** * 解析日期 yyyy-MM-dd HH:mm:ss * * @param timestamp * @return */ public static String format(Long timestamp, String pattern) { String dateStr = ""; if (null == timestamp || timestamp.longValue() < 0) { return dateStr; } try { Date date = new Date(timestamp); SimpleDateFormat format = new SimpleDateFormat(pattern); dateStr = format.format(date); } catch (Exception e) { // ignore } return dateStr; } /** * 解析日期 yyyy-MM-dd HH:mm:ss * * @param timestamp * @return */ public static String format(Long timestamp) { String dateStr = ""; if (null == timestamp || timestamp.longValue() < 0) { return dateStr; } try { Date date = new Date(timestamp); SimpleDateFormat format = new SimpleDateFormat(FORMAT_TIME); dateStr = format.format(date); } catch (Exception e) { // ignore } return dateStr; } /** * 获取当前时间前几天时间,按指定格式返回 * * @param days * @return */ public static String forwardDay(Integer days, String format) { DateTime dt = new DateTime(); DateTime y = dt.minusDays(days); return y.toString(format); } /** * 获取当前时间前几天时间 * * @param days * @return */ public static Date forwardDay(Integer days) { DateTime dt = new DateTime(); DateTime y = dt.minusDays(days); return y.toDate(); } /** * 获取指定时间之后或者之前的某一天00:00:00 默认返回当天 * * @param days * @return */ public static Date day00(Integer days, String date, String zimeZone) throws Throwable { DateTime dt; TimeZone timeZone; try { if (isBlank(zimeZone)) { timeZone = TimeZone.getDefault(); } else { timeZone = TimeZone.getTimeZone(zimeZone); } if (isBlank(date)) { dt = new DateTime().withZone(DateTimeZone.forTimeZone(timeZone)).toLocalDateTime().toDateTime(); } else { dt = new DateTime(date).withZone(DateTimeZone.forTimeZone(timeZone)).toLocalDateTime().toDateTime(); } } catch (Exception e) { throw new Throwable(e); } DateTime y = dt.minusDays(days).withHourOfDay(0).withMinuteOfHour(0).withSecondOfMinute(0); return y.toDate(); } /** * 获取指定时间之后或者之前的某一天23:59:59 默认返回当天 * * @param days * 偏移量 * @return */ public static Date day59(Integer days, String date, String zimeZone) throws Throwable { DateTime dt; TimeZone timeZone; try { if (isBlank(zimeZone)) { timeZone = TimeZone.getDefault(); } else { timeZone = TimeZone.getTimeZone(zimeZone); } if (isBlank(date)) { dt = new DateTime().withZone(DateTimeZone.forTimeZone(timeZone)).toLocalDateTime().toDateTime(); } else { dt = new DateTime(date).withZone(DateTimeZone.forTimeZone(timeZone)).toLocalDateTime().toDateTime(); } } catch (Exception e) { throw new Throwable(e); } DateTime y = dt.minusDays(days).withHourOfDay(23).withMinuteOfHour(59).withSecondOfMinute(59); return y.toDate(); } /** * 计算两个时间相差多少天 * * @param startDate * @param endDate * @return */ @Nullable public static Integer diffDay(Date startDate, Date endDate) { if (startDate == null || endDate == null) { return null; } DateTime dt1 = new DateTime(startDate); DateTime dt2 = new DateTime(endDate); int day = Days.daysBetween(dt1, dt2).getDays(); return Math.abs(day); } /** * 获取某月之前,之后某一个月最后一天,24:59:59 * * @return */ public static Date lastDay(Date date, Integer month) { DateTime dt1; if (month == null) { month = 0; } if (date == null) { dt1 = new DateTime().minusMonths(month); } else { dt1 = new DateTime(date).minusMonths(month); } DateTime lastDay = dt1.dayOfMonth().withMaximumValue().withHourOfDay(23).withMinuteOfHour(59) .withSecondOfMinute(59); return lastDay.toDate(); } /** * 获取某月月之前,之后某一个月第一天,00:00:00 * * @return */ public static Date firstDay(Date date, Integer month) { DateTime dt1; if (month == null) { month = 0; } if (date == null) { dt1 = new DateTime().minusMonths(month); } else { dt1 = new DateTime(date).minusMonths(month); } DateTime lastDay = dt1.dayOfMonth().withMinimumValue().withHourOfDay(0).withMinuteOfHour(0) .withSecondOfMinute(0); return lastDay.toDate(); } public static Date addDay(Date date, int offset) { DateTime dt1; if (date == null) { dt1 = new DateTime().plusDays(offset); return dt1.toDate(); } dt1 = new DateTime(date).plusDays(offset); return dt1.toDate(); } /** * 传入日期时间与当前系统日期时间的比较, 若日期相同,则根据时分秒来返回 , 否则返回具体日期 * * @return 日期或者 xx小时前||xx分钟前||xx秒前 */ @Nullable public static String getNewUpdateDateString(Date now, Date createDate) { if (now == null || createDate == null) { return null; } Long time = (now.getTime() - createDate.getTime()); if (time > (24 * 60 * 60 * 1000)) { return time / (24 * 60 * 60 * 1000) + "天前"; } else if (time > (60 * 60 * 1000)) { return time / (60 * 60 * 1000) + "小时前"; } else if (time > (60 * 1000)) { return time / (60 * 1000) + "分钟前"; } else if (time >= 1000) { return time / 1000 + "秒前"; } return "刚刚"; } /** * * @Title: isBlank * @Description: TODO(判断字符串是否为空或长度为0 或由空格组成) * @param @param str * @param @return 设定文件 * @return boolean 返回类型 * @throws */ public static boolean isBlank(String str) { return (str == null || str.trim().length() == 0); } public static void main(String[] args) throws Throwable { System.out.println(lastDay(new Date(),2)); System.out.println(firstDay(null,0)); TimeZone zone1=TimeZone.getTimeZone("GMT+8"); TimeZone zone2=TimeZone.getTimeZone("GMT-5"); System.out.println(format(new Date(),zone1,FORMAT_TIME)); System.out.println(format(new Date(),zone2,FORMAT_TIME)); System.out.println(format(day00(0,"2017-5-11","GMT+0"))); System.out.println(format(day00(0,"2017-5-11","GMT+8"))); System.out.println(format(day00(0,"2017-5-11","GMT-8"))); Date date1 =parse("2017-05-11 17:53:52"); System.out.println(diffDay(date1,new Date())); DateTime dateTime = new DateTime().withDayOfWeek(1); DateTime dateTime1 = new DateTime().withDayOfWeek(7).withTime(0, 0, 0, 0); System.out.println(format(dateTime.toDate())); System.out.println(format(dateTime1.toDate())); System.out.println(format(new Date(), "MM/dd")); } }
其中测试代码结果:
Fri Jun 30 23:59:59 GMT+08:00 2017 Tue Aug 01 00:00:00 GMT+08:00 2017 2017-08-28 19:47:28 2017-08-28 06:47:28 2017-05-10 00:00:00 2017-05-11 00:00:00 2017-05-10 00:00:00 109 2017-08-28 19:47:29 2017-09-03 00:00:00 08/28
时间: 2024-10-15 18:35:32