Java 日期格式化

import java.text.SimpleDateFormat;
import java.util.Date;

public class Test4 {

    public static void main(String[] args) {
        /**
         * Letter  Date or Time Component  Presentation  Examples
         * G  Era designator  Text  AD
         * y  Year  Year  1996; 96
         * Y  Week year  Year  2009; 09
         * M  Month in year (context sensitive)  Month  July; Jul; 07
         * L  Month in year (standalone form)  Month  July; Jul; 07
         * w  Week in year  Number  27
         * W  Week in month  Number  2
         * D  Day in year  Number  189
         * d  Day in month  Number  10
         * F  Day of week in month  Number  2
         * E  Day name in week  Text  Tuesday; Tue
         * u  Day number of week (1 = Monday,...,7 = Sunday)  Number  1
         * a  Am/pm marker  Text  PM
         * H  Hour in day (0-23)  Number  0
         * k  Hour in day (1-24)  Number  24
         * K  Hour in am/pm (0-11)  Number  0
         * h  Hour in am/pm (1-12)  Number  12
         * m  Minute in hour  Number  30
         * s  Second in minute  Number  55
         * S  Millisecond  Number  978
         * z  Time zone  General time zone  Pacific Standard Time; PST; GMT-08:00
         * Z  Time zone  RFC 822 time zone  -0800
         * X  Time zone  ISO 8601 time zone  -08; -0800; -08:00
         */
        Date date = new Date();
        System.out.println("当前时间：" + date);
        SimpleDateFormat sdf = new SimpleDateFormat("YYYY年MM月dd日 HH:mm:ss SSS");
        String dateStr = sdf.format(date);
        System.out.println("当前时间：" + dateStr);
        /** 显示如下
         * 当前时间：Wed Oct 02 12:40:41 GMT+08:00 2019
         * 当前时间：2019年10月02日 12:40:41 687
         */

    }
}