MarkLogic base64 encoding of a binary file using MLJAM

MarkLogic has the function xdmp:base64-encode, which unfortunately only works on xs:string's.

I needed a function to convert an arbitrary file (ie. binary) into a base64 encoded stream in order to put it into an atom+xml http post to feed Alfresco document management system.  Luckily I found MLJAM, which allows you to embed Java into xquery.  I found the needed Java snippet here, and then put it together - the code below should work in the MarkLogic Query console, just set the filename parameter accordingly.

Ultimately MarkLogic should have xdmp:base64-encode work on a binary node, then you could simply do xdmp:base64-encode(xdmp:external-binary("/some/path/image.png"))!

xquery version "1.0-ml";

import module namespace jam = "http://xqdev.com/jam" at "/MarkLogic/jam.xqy";

let $code := <code><![CDATA[

import org.apache.commons.codec.binary.Base64;

private String encodeFileToBase64Binary(String fileName)

throws IOException {

File file = new File(fileName);

byte[] bytes = loadFile(file);

byte[] encoded = Base64.encodeBase64(bytes);

String encodedString = new String(encoded);

return encodedString;

}

 

private static byte[] loadFile(File file) throws IOException {

   InputStream is = new FileInputStream(file);

     long length = file.length();

   if (length > Integer.MAX_VALUE) {

       // File is too large

   }

   byte[] bytes = new byte[(int)length];

   

   int offset = 0;

   int numRead = 0;

   while (offset < bytes.length

          && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {

       offset += numRead;

   }

 

   if (offset < bytes.length) {

       throw new IOException("Could not completely read file "+file.getName());

   }

 

   is.close();

   return bytes;

}

  

    return encodeFileToBase64Binary(filename);

]]></code>

  

let $path := "http://localhost:8080/mljam/mljam"

let $connect := jam:start($path, (), ())

let $vars := jam:set("filename", "/some/path/image.png")

let $eval := jam:eval-get($code)

let $end := jam:end()

return $eval