解码
encoding := base64.StdEncoding
data := []byte(`Zm9vIGJhcg==`)
decoded := make([]byte, encoding.DecodedLen(len(data)))
n, err := encoding.Decode(decoded, data)
if err != nil {
log.Fatal(err)
}
// Because we don't know the length of the data that is encoded
// (only the max length), we need to trim the buffer to whatever
// the actual length of the decoded data was.
decoded = decoded[:n]
fmt.Printf("`%s`", decoded)
// Output: `foo bar`