Golang: 獲取 []byte 的 size

https://play.golang.org/p/HhJif66VwY

https://stackoverflow.com/questions/31733145/size-of-a-byte-array-golang

https://stackoverflow.com/questions/14697771/size-in-bytes-of-the-content-of-a-slice

https://learnku.com/articles/23411/the-difference-between-rune-and-byte-of-go

https://www.cnblogs.com/mushroom/p/8998538.html