Clojure equivalent of python's base64 encode and decode [duplicate]

问题

This question already has answers here:

Clojure base64 encoding (6 answers)

Closed 3 years ago.

I have this python code snippet and need help with a clojure equivalent.

user_id = row.get('user_id')
if user_id:
    user_id_bytes = base64.urlsafe_b64decode(user_id)
    creation_timestamp = int.from_bytes(user_id_bytes[:4],
                                    byteorder='big')
    dc_id = int.from_bytes(user_id_bytes[4:5], byteorder='big') & 31
    if creation_timestamp > WHEN_WE_SET_UP_DC_IDS:
        row['dc_id'] = dc_id}

回答1:

You can use clojure's java compatibility to leverage the java.util.Base64 class.

user> (import java.util.Base64)
java.util.Base64

user> ;; encode a message
     (let [message "Hello World!"
           message-bytes (.getBytes message) 
           encoder (Base64/getUrlEncoder)]
       (.encodeToString encoder message-bytes)) 
"SGVsbG8gV29ybGQh"

user> ;; Decode a message
      (let [encoded-message "SGVsbG8gV29ybGQh"
            decoder (Base64/getUrlDecoder)]
        (String. (.decode decoder encoded-message)))
"Hello World!"

回答2:

The Tupelo library has Clojure wrappers around the Java Base64 and Base64Url functionality. A look at the unit tests show the code in action:

(ns tst.tupelo.base64
  (:require [tupelo.base64 :as b64] ))

code-str    (b64/encode-str  orig)
result      (b64/decode-str  code-str) ]
(is (= orig result))

where the input & output values are plain strings (there is also a variant for byte arrays).

The API docs are here.

来源：https://stackoverflow.com/questions/39642549/clojure-equivalent-of-pythons-base64-encode-and-decode