[go time] go time #go #time

time.go

// 获取指定月份的天数
package main

import (
	"fmt"
	"time"
)

func days(year int, month time.Month) int {
	return time.Date(year, month+1, 0, 0, 0, 0, 0, time.UTC).Day()
}

func main() {
	fmt.Println(days(2019, 2)) // 28
	fmt.Printf("%v", time.Date(2019, 3, 0, 0, 0, 0, 0, time.UTC)) // 2019-02-28 00:00:00 +0000 UTC
}

// 时间格式化
package main

import (
	"fmt"
	"time"
)

func main() {
	fmt.Println(time.Now().Format("2006-01-02 15:04:05"))
}

time1.go

// 计算程序运行时间
package main

import (
	"fmt"
	"time"
)

func main() {
	startTime := time.Now()
	time.Sleep(1 * time.Second)
	elapsed := time.Since(startTime)
	fmt.Printf("elapsed %v", elapsed) // elapsed 1.0005049s
}

time2.md

time 包 After 源码

// After waits for the duration to elapse and then sends the current time
// on the returned channel.
// It is equivalent to NewTimer(d).C.
// The underlying Timer is not recovered by the garbage collector
// until the timer fires. If efficiency is a concern, use NewTimer
// instead and call Timer.Stop if the timer is no longer needed.
func After(d Duration) <-chan Time {
    return NewTimer(d).C
}

调用time.After(duration)后,此函数马上返回,返回一个time.Time类型的 Chan,不阻塞,后面你该做什么做什么,不影响,到了duration时间后,自动发送当前时间到管道中,经常与 select 一起使用.

func requestWithTimeout(timeout time.Duration) (int, error) {
	c := make(chan int)
	// May need a long time to get the response.
	go doRequest(c)

	select {
	case data := <-c:
		return data, nil
	case <-time.After(timeout):
		return 0, errors.New("timeout")
	}
}