java日期格式规范（JDK1.8官方文档）

Symbol	Meaning	Presentation	Examples
G	era	text	AD;
u	year	year	2004;
y	year-of-era	year	2004;
D	day-of-year	number	189
M/L	month-of-year	number/text	7;
d	day-of-month	number	10
Q/q	quarter-of-year	number/text	3;
Y	week-based-year	year	1996;
w	week-of-week-based-year	number	27
W	week-of-month	number	4
E	day-of-week	text	Tue;
e/c	localized	day-of-week	number/text
F	week-of-month	number	3
a	am-pm-of-day	text	PM
h	clock-hour-of-am-pm	(1-12)	number
K	hour-of-am-pm	(0-11)	number
k	clock-hour-of-am-pm	(1-24)	number
H	hour-of-day	(0-23)	number
m	minute-of-hour	number	30
s	second-of-minute	number	55
S	fraction-of-second	fraction	978
A	milli-of-day	number	1234
n	nano-of-second	number	987654321
N	nano-of-day	number	1234000000
V	time-zone	ID	zone-id
z	time-zone	name	zone-name
O	localized	zone-offset	offset-O
X	zone-offset	‘Z’	for
x	zone-offset	offset-x	+0000;
Z	zone-offset	offset-Z	+0000;
p	pad	next	pad
‘	escape	for	text
”	single	quote	literal
[	optional	section	start
]	optional	section	end
#	reserved	for	future
{	reserved	for	future
}	reserved	for	future