Go语言学习笔记(五)

11.时间和日期类型(time包)

a.time.Time用来表示时间,time.Now()获取当前时间
b.time.Now().Day()，time.Now().Minute(), time.Now().Month(),time.Now().Year()，
类似的还有Hour,Minute,Second
c.格式化输出fmt.Printf("%02d/%02d%02d%02d:%02d:%02d", now.Year()……)

  1: func testTime(){
  2: 	now := time.Now()
  3: 	fmt.Printf("now_time:%v
", now)
  4: 
  5: 	year := now.Year()
  6: 	month := now.Month()
  7: 	day := now.Day()
  8: 	hour := now.Hour()
  9: 	minute := now.Minute()
 10: 	fmt.Printf("%02d-%02d-%02d-%02d-%02d
", year, month, day, hour, minute)
 11: 	time_stamp := now.Unix()
 12: 	fmt.Printf("time_stamp_year:%d
", time_stamp/3600/24/30/12)
 13: }

另外一种格式化输出（Go语言诞生时间，具体时间是固定的）：

  1: 	fmt.Printf(now.Format("02/1/2006 15：04
"))
  2: 	fmt.Printf(now.Format("2006/1/02 15:04
"))
  3: 	fmt.Printf(now.Format("2006/1/02
"))

输出：

  1: 08/12/2018 16：10
  2: 2018/12/08 16:10
  3: 2018/12/08

d.获取当前的时间戳：time.Now().Unix(),时间戳可以转Time类型

  1: func testTimestamp(timestamp int64) {
  2: 	timeObj := time.Unix(timestamp, 0)
  3: 	year := timeObj.Year()
  4: 	month := timeObj.Month()
  5: 	day := timeObj.Day()
  6: 	hour := timeObj.Hour()
  7: 	minute := timeObj.Minute()
  8: 	fmt.Printf("%02d-%02d-%02d-%02d-%02d
", year, month, day, hour, minute)
  9: }
 10: func main(){
 11: 	// testTime()
 12: 	time_stamp := time.Now().Unix()
 13: 	testTimestamp(time_stamp)
 14: }

e.定时器的简单用法

  1: func processTask(){
  2: 	fmt.Printf("do task
")
  3: }
  4: func testTicker(){
  5: 	ticker := time.Tick(2*time.Second)
  6: 	for i := range ticker {
  7: 		fmt.Printf("%v
", i)
  8: 		processTask()
  9: 	}
 10: }

f.time.Duration表示纳秒
一些常量:

  1: const(
  2: 	Nanosecond Duration = 1
  3: 	Microsecond = 1000*Nanosecond
  4: 	Millisecond = 1000*Microsecond
  5: 	Second = 1000*Millisecond
  6: 	Minute = 60*Second
  7: 	Hour = 60*Minute
  8: )

小练习：

1.获取当前时间，并格式化成2017/06/15 08:05:00

两种写法

  1: func get_time(){
  2: 	now := time.Now()
  3: 	year := now.Year()
  4: 	month := now.Month()
  5: 	day := now.Day()
  6: 	hour := now.Hour()
  7: 	minute := now.Minute()
  8: 	second := now.Second()
  9: 	fmt.Printf("%04d/%02d/%02d %02d:%02d:%02d
", year, month, day, hour, minute, second)
 10: }
 11: 
 12: func get_time_2(){
 13: 	now := time.Now()
 14: 	timeStr := now.Format("2006/01/02 15:04:05")
 15: 	fmt.Printf("time:%v
", timeStr)
 16: }

2.统计一段代码的执行耗时,单位精确到微秒

  1: func testCost(){
  2: 	start := time.Now().UnixNano()
  3: 	for i:=0;i<10;i++{
  4: 		time.Sleep(time.Millisecond)
  5: 	}
  6: 	end := time.Now().UnixNano()
  7: 	cost := (end - start)/1000
  8: 	fmt.Printf("cost:%d", cost)
  9: }