Java - 時間戳記、Date、Calendar、SimpleDateFormat

標籤：ati   finish   格式化   print   pre   long   sim   led   calendar   

Java

package com.ikoo.demo; import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date; public class DateUtil {    public static void main(String[] args) {        /**         * 時間戳記         * 1.System.currentTimeMillis()         * 2.new Date().getTime()         * 3.Calendar.getInstance().getTimeInMillis()         * P.S.         *  Java擷取時間戳記精確到毫秒級，Unix中精確到秒級，所以Java擷取的時間戳記需要除以1000，就可以保證一致性         *  Calendar.getInstance().getTimeInMillis() 耗時最多，這是因為Canlendar要處理時區問題         */        System.out.println("System.currentTimeMillis(): " + System.currentTimeMillis());        System.out.println("new Date().getTime(): " + new Date().getTime());        System.out.println("Calendar.getInstance().getTimeInMillis(): " + Calendar.getInstance().getTimeInMillis());        System.out.println("----------");         /**         * 時間戳記（日期）轉換自訂日期格式         */        long timeStamp = System.currentTimeMillis();        System.out.println("System.currentTimeMillis(): " + timeStamp);        Date date = new Date();        System.out.println("new Date(): " + date);        long dateTimaStamp = date.getTime();        System.out.println("date.getTime(): " + date.getTime());        String formatDate0 = DateUtil.timeStampToFormatDate(System.currentTimeMillis(), "yyyy-MM-dd HH:mm:ss");        System.out.println("formatDate0: " + formatDate0);        String formatDate1 = DateUtil.timeStampToFormatDate(new Date(), "yyyy-MM-dd HH:mm:ss");        System.out.println("formatDate1: " + formatDate1);        String formatDate2 = DateUtil.timeStampToFormatDate(new Date().getTime(), "yyyy-MM-dd HH:mm:ss");        System.out.println("formatDate2: " + formatDate2);        String formatDate3 = DateUtil.timeStampToFormatDate(Calendar.getInstance().getTime(), "yyyy-MM-dd HH:mm:ss");        System.out.println("formatDate3: " + formatDate3);    }     /**     * 時間戳記轉換為格式化日期     *     * @param dateObj 時間對象     *                System.currentTimeMillis()     *                new Date()     *                new Date().getTime()     *                Calendar.getInstance().getTimeInMillis()     * @param pattern 日期格式     *                yyyy-MM-dd HH:mm:ss     *                yyyy/MM/dd HH:mm:ss     *                yyyy年MM月dd日 HH:mm:ss     * @return sdf.format(Object dateObj)     */    public static String timeStampToFormatDate(Object dateObj, String pattern) {        SimpleDateFormat sdf = new SimpleDateFormat(pattern);        String formatDate = sdf.format(dateObj);        return formatDate;    }}

 
控制台列印結果：

System.currentTimeMillis(): 1503660334272new Date().getTime(): 1503660334274Calendar.getInstance().getTimeInMillis(): 1503660334299----------System.currentTimeMillis(): 1503660334328new Date(): Fri Aug 25 19:25:34 CST 2017date.getTime(): 1503660334328formatDate0: 2017-08-25 19:25:34formatDate1: 2017-08-25 19:25:34formatDate2: 2017-08-25 19:25:34formatDate3: 2017-08-25 19:25:34 Process finished with exit code 0

Java - 時間戳記、Date、Calendar、SimpleDateFormat