您好,登錄后才能下訂單哦!
本篇內(nèi)容介紹了“用Calendar、Date和SimperFormat獲取當(dāng)前時(shí)間的區(qū)別”的有關(guān)知識,在實(shí)際案例的操作過程中,不少人都會遇到這樣的困境,接下來就讓小編帶領(lǐng)大家學(xué)習(xí)一下如何處理這些情況吧!希望大家仔細(xì)閱讀,能夠?qū)W有所成!
Calendar calendar = Calendar.getInstance(); System.out.println("目前時(shí)間: " + calendar.getTime()); System.out.println("Calendar時(shí)區(qū): " + calendar.getTimeZone().getID()); System.out.println("user.timezone: " + System.getProperty("user.timezone")); System.out.println("user.country: " + System.getProperty("user.country")); System.out.println("默認(rèn)時(shí)區(qū): " + TimeZone.getDefault().getID());
運(yùn)行結(jié)果:
目前時(shí)間: Tue May 28 23:09:31 CST 2019
Calendar時(shí)區(qū): Asia/Shanghai
user.timezone: Asia/Shanghai
user.country: CN
默認(rèn)時(shí)區(qū): Asia/Shanghai
long start1 = System.currentTimeMillis(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//設(shè)置日期格式 System.out.println(sdf.format(new Date()));// new Date()為獲取當(dāng)前系統(tǒng)時(shí)間 long end1 = System.currentTimeMillis(); System.out.println((end1 - start1) + "ms");
運(yùn)行結(jié)果:
2019-05-28 23:14:14
55ms
long start2 = System.currentTimeMillis(); Calendar calendar = Calendar.getInstance();//可以對每個時(shí)間域單獨(dú)修改 System.out.println(calendar.get(Calendar.YEAR) + "-" + calendar.get(Calendar.MONTH) + "-" + calendar.get(Calendar.DATE) + " " + calendar.get(Calendar.HOUR_OF_DAY) + ":" + calendar.get(Calendar.MINUTE) + ":" + calendar.get(Calendar.SECOND)); long end2 = System.currentTimeMillis(); System.out.println((end2 - start2) + "ms");
運(yùn)行結(jié)果:
2019-4-28 23:15:22
36ms
顯然,第二種的Calendar獲取當(dāng)前時(shí)間的性能比SimpleDateFormat的要快
long start3 = System.currentTimeMillis(); Calendar calendar = Calendar.getInstance(); calendar.setTime(new Date()); calendar.set(Calendar.HOUR_OF_DAY, 0); calendar.set(Calendar.MINUTE, 0); calendar.set(Calendar.SECOND, 0); Date zero = calendar.getTime(); long end3 = System.currentTimeMillis(); System.out.println(zero); System.out.println((end3 - start3) + "ms");
運(yùn)行結(jié)果:
Tue May 28 00:00:00 CST 2019
34ms
long start4 = System.currentTimeMillis(); long current = System.currentTimeMillis(); long zero = current/(1000*3600*24)*(1000*3600*24) - TimeZone.getDefault().getRawOffset(); System.out.println(zero); long end4 = System.currentTimeMillis(); System.out.println((end4 - start4) + "ms");
運(yùn)行結(jié)果:
1558972800000
11ms
這里current表示毫秒,那么除以了1000 * 3600 * 24得到天數(shù),但是可能不是整數(shù)天,但是因?yàn)閠是long型,那么小數(shù)部分沒有了,再去乘以1000 * 3600 * 24,就變成整數(shù)天數(shù)所對應(yīng)的毫秒了。
TimeZone.getDefault().getRawOffset() 計(jì)算夏令時(shí)和返回當(dāng)前時(shí)區(qū)與格林尼治時(shí)間的偏差。
顯然,這里獲取零點(diǎn)時(shí)間強(qiáng)烈推薦第二種方法,性能比第一種高三倍左右。
import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class TestDate { /** * 獲取當(dāng)前年份、月份、日期 * @param args */ public static void main(String[] args) { Calendar cale = null; cale = Calendar.getInstance(); int year = cale.get(Calendar.YEAR); int month = cale.get(Calendar.MONTH) + 1; int day = cale.get(Calendar.DATE); int hour = cale.get(Calendar.HOUR_OF_DAY); int minute = cale.get(Calendar.MINUTE); int second = cale.get(Calendar.SECOND); int dow = cale.get(Calendar.DAY_OF_WEEK); int dom = cale.get(Calendar.DAY_OF_MONTH); int doy = cale.get(Calendar.DAY_OF_YEAR); System.out.println("Current Date: " + cale.getTime()); System.out.println("Year: " + year); System.out.println("Month: " + month); System.out.println("Day: " + day); System.out.println("Hour: " + hour); System.out.println("Minute: " + minute); System.out.println("Second: " + second); System.out.println("Day of Week: " + dow); System.out.println("Day of Month: " + dom); System.out.println("Day of Year: " + doy); // 獲取當(dāng)月第一天和最后一天 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); String firstday, lastday; // 獲取前月的第一天 cale = Calendar.getInstance(); cale.add(Calendar.MONTH, 0); cale.set(Calendar.DAY_OF_MONTH, 1); firstday = format.format(cale.getTime()); // 獲取前月的最后一天 cale = Calendar.getInstance(); cale.add(Calendar.MONTH, 1); cale.set(Calendar.DAY_OF_MONTH, 0); lastday = format.format(cale.getTime()); System.out.println("本月第一天和最后一天分別是 : " + firstday + " and " + lastday); // 獲取當(dāng)前日期字符串 Date d = new Date(); System.out.println("當(dāng)前日期字符串1:" + format.format(d)); System.out.println("當(dāng)前日期字符串2:" + year + "/" + month + "/" + day + " " + hour + ":" + minute + ":" + second); } }
“用Calendar、Date和SimperFormat獲取當(dāng)前時(shí)間的區(qū)別”的內(nèi)容就介紹到這里了,感謝大家的閱讀。如果想了解更多行業(yè)相關(guān)的知識可以關(guān)注億速云網(wǎng)站,小編將為大家輸出更多高質(zhì)量的實(shí)用文章!
免責(zé)聲明:本站發(fā)布的內(nèi)容(圖片、視頻和文字)以原創(chuàng)、轉(zhuǎn)載和分享為主,文章觀點(diǎn)不代表本網(wǎng)站立場,如果涉及侵權(quán)請聯(lián)系站長郵箱:is@yisu.com進(jìn)行舉報(bào),并提供相關(guān)證據(jù),一經(jīng)查實(shí),將立刻刪除涉嫌侵權(quán)內(nèi)容。