How to decode bson by java or clojure

I want to decode BSON file to Clojure card.

This is my code:

(ns decode
  (:require [clojure.java.io :as cji])
  (:import [org.bson BasicBSONObject BasicBSONEncoder BasicBSONDecoder]))

(defonce encoder (BasicBSONEncoder.))

(defonce decoder (BasicBSONDecoder.))

(defn read-file [file-path]
  (with-open [reader (cji/input-stream file-path)]
    (let [length (.length (clojure.java.io/file file-path))
          buffer (byte-array length)]
      (.read reader buffer 0 length)
      buffer)))


(defn bson2map [^Byte b]
  (->> (.readObject decoder b) (.toMap) (into {})))

(defn read-bson
  [path]
 (clojure.walk/keywordize-keys (bson2map (read-file path))))

      

        
        
        
      

    

But when I decode a BSON file like this (r/read-bson "test.bson")

, it just decodes the first entry and I want to decode them all. test.bson

too big. How to decode it in fragments?

Then I found a class called LazyBSONDecoder

, wrote some java code and it works, it can decode all entries.

import org.bson.LazyBSONDecoder;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

public class Main {

    public static void main(String[] args) throws IOException {
        InputStream in = new FileInputStream("./_Installation.bson");
        LazyBSONDecoder decoder = new LazyBSONDecoder();
        Object obj;
        int count = 0;
        try {
            do {
                obj = decoder.readObject(in);
                System.out.println(obj);
                count++;
            } while (obj != null);
        } catch (Exception e) {
            // ignore
        }
        System.out.println(count);
    }
}

      

        
        
        
      

    

So, I changed the Clojure code to replace BasicBSONDecoder

with LazyBSONDecoder

, but it always just decodes the first entry.

(defonce decoder (LazyBSONDecoder.))

(defn bson2map [^Byte b]
  (do (print (.readObject decoder b))
      (print (.readObject decoder b))
      (print (.readObject decoder b))))