时间格式化

String.format("%tM",date);

String.format("%tw",date);

Letter Date or Time Component Presentation Examples 

G Era designator Text AD 

y Year Year 1996； 96 

M Month in year 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 in week Text Tuesday； Tue

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 zon