time包地址：https://pkg.go.dev/time@go1.19.4

time包的作用：Package time provides functionality for measuring and displaying time.
The calendrical calculations always assume a Gregorian calendar, with no leap seconds.

常见的用法：
now = time.Now
now.Format(...)
now.Sub(t)
now.Unix()
now.UnixNano()

const:
time.Second
time.Minute
time.Hour
（应用场景：time.Sleep(time.Second * 5)  -- > 休眠5秒）

func：
d.Hours()
d.Minute()
d.Second()
（将一个time.Duration的d分别转换为小时/分钟/秒）

如何格式化一个时间或日期：
参考文章:
https://yourbasic.org/golang/format-parse-string-time-date-example/

base64包地址：https://pkg.go.dev/encoding/base64@go1.19.4

base64包的作用：Package base64 implements base64 encoding as specified by RFC 4648.

常用func：
1.base64.RawStdEncoding（.EncodeToString/.DecodeString）
2.base64.URLEncoding（.EncodeToString/.DecodeString）
3.base64.RawURLEncoding（.EncodeToString/.DecodeString）
4.base64.StdEncoding.EncodeToString
  函数：func (enc *Encoding) EncodeToString(src  []byte) string
  返回值：EncodeToString returns the base64 encoding of src
5.base64.StdEncoding.DecodeString
  函数：func (enc *Encoding)  DecodeString(s string)  ([]byte, error)
  返回值：DecodeString returns the bytes represented by the base64 string s

log包地址：https://pkg.go.dev/log

log包的作用：Package log implements a simple logging package. It defines a type, Logger, with methods for formatting output. It also has a predefined 'standard' Logger accessible through helper functions Print[f|ln], Fatal[f|ln], and Panic[f|ln], which are easier to use than creating a Logger manually. That logger writes to standard error and prints the date and time of each logged message. Every log message is output on a separate line: if the message being printed does not end in a newline, the logger will add one. The Fatal functions call os.Exit(1) after writing the log message. The Panic functions call panic after writing the log message.

常用：
Fatal：打印日志，并退出程序
Fatalf
Fatalln

Panic：打印日志，并产生panic
Panicf
Panicln

Printf：打印日志（最常用）
Println

SetFlags
Flags

SetOutput：把日志写到文件里

SetPrefix: 在日志前加上前缀，可用于对日志进行分类

Flag
SetFlags