3.旧时间、日历

该groovy-dateutil模块支持使用 Java 的经典Date和Calendar类的许多扩展。
您可以使用类中的常量字段编号访问 Date或Calendar使用普通数组索引表示法的属性，Calendar如以下示例所示：

// 导入常量
import static java.util.Calendar.*    
def cal = Calendar.instance
// 设置日历的年月
cal[YEAR] = 2000
cal[MONTH] = JANUARY                  
cal[DAY_OF_MONTH] = 1
// 访问日历的星期几                 
assert cal[DAY_OF_WEEK] == SATURDAY

Groovy 支持实例之间的算术运算和迭代Date，Calendar如以下示例所示：

def utc = TimeZone.getTimeZone('UTC')
Date date = Date.parse("yyyy-MM-dd HH:mm", "2010-05-23 09:01", utc)

def prev = date - 1
def next = date + 1

def diffInDays = next - prev
assert diffInDays == 2

int count = 0
prev.upto(next) { count++ }
assert count == 3

您可以将字符串解析为日期，并将日期输出为格式化字符串：

def orig = '2000-01-01'
def newYear = Date.parse('yyyy-MM-dd', orig)
assert newYear[DAY_OF_WEEK] == SATURDAY
assert newYear.format('yyyy-MM-dd') == orig
assert newYear.format('dd/MM/yyyy') == '01/01/2000'

您还可以根据现有日期或日历创建新的日期或日历：

def newYear = Date.parse('yyyy-MM-dd', '2000-01-01')
def newYearsEve = newYear.copyWith(
    year: 1999,
    month: DECEMBER,
    dayOfMonth: 31
)
assert newYearsEve[DAY_OF_WEEK] == FRIDAY