将“ =？UTF 8？..”（RFC 2047）转换为golang中的常规字符串

I'm using an API and it's returning something like this for other language text:

=?UTF 8?B?2KfZhNiu2LfZiNin2Kog2KfZhNiq2Yog2KrYrNmF2Lkg2KjZitmG?= =?UTF 8?B?INit2YHYuCDYp9mE2YLYsdin2ZPZhiDYp9mE2YPYsdmK2YUg2YjZgQ==?= =?UTF 8?B?2YfZhdmHINmF2YXYpyDYp9mU2YXZhNin2Ycg2KfZhNi52YTYp9mF?= =?UTF 8?B?2Kkg2LnYqNivINin2YTZhNmHINin2YTYutiv2YrYp9mGLnBkZg==?=

Is this a common format? How would I go about converting this to a regular string in golang?

Golang usually handles multiple languages well, but I'm not sure about how to go about converting.

Aparrently your API is returning data encoded in RFC 2047 format. Basically, this defines the following:

encoded-word = "=?" charset "?" encoding "?" encoded-text "?="

Which means your charset is UTF-8 (very handy, since this is Go's native character set), and your encoding is Base64. The text you have to decode is the one between the "B?" and the "?=". So all you have to do is take that text and call:

base64.StdEncoding.DecodeString(text)

to get the original UTF-8 string.

There is a decodeRFC2047Word() function in the net/mail package of the Go stdlib, supporting encodings B and Q and charsets UTF-8, US-ASCII and ISO-8859-1. Unfortunately it's not exported, but you're free to take as much inspiration from it as you need ;)

BTW: I just noticed the charset in your example strings is UTF 8, which is a bit odd, since the official name of the encoding is UTF-8.

Since Go 1.5 you can use mime.WordDecoder.DecodeHeader:

package main

import (
    "fmt"
    "mime"
)

func main() {
    dec := new(mime.WordDecoder)
    header, err := dec.DecodeHeader("=?UTF-8?B?2KfZhNiu2LfZiNin2Kog2KfZhNiq2Yog2KrYrNmF2Lkg2KjZitmG?= =?UTF-8?B?INit2YHYuCDYp9mE2YLYsdin2ZPZhiDYp9mE2YPYsdmK2YUg2YjZgQ==?= =?UTF-8?B?2YfZhdmHINmF2YXYpyDYp9mU2YXZhNin2Ycg2KfZhNi52YTYp9mF?= =?UTF-8?B?2Kkg2LnYqNivINin2YTZhNmHINin2YTYutiv2YrYp9mGLnBkZg==?=")
    if err != nil {
        panic(err)
    }
    fmt.Println(header)
    // Output: لخطوات التي تجمع بين حفظ القرآن الكريم وفهمه مما أملاه العلامة عبد الله الغديان.pdf
}

If you are using an older version of Go, you can use my replacement library: https://github.com/alexcesaro/quotedprintable