Base64 encoded string differs in perl and Java

Question

when i encode a pdf file into base64 binary(using commons lib) in java , I got string(sample) like "SGVsbG8gV_29y-bGQ="

But if i encode the same file using perl , I got like "SGVsbG8gV/29y+bGQ="

Difference in string: / instead of _ , + instead of -

Why i am getting like this? Or, Is there any way to fix without string replace ?

in java

byte[] data;
        try (java.io.FileInputStream fin = new java.io.FileInputStream(new java.io.File("file.pdf"))) {
            data = new byte[fin.available()];
            fin.read(data);
        }
        return data;
System.out.println("ecncoded value is " + DatatypeConverter.printBase64Binary(data));

In Perl

use MIME::Base64;

open (PDF, "file.pdf") or die "$!";

$raw_string = do{ local $/ = undef; <PDF>; };
$encoded = encode_base64( $raw_string );

print " \n";
print " $encoded ";

// Java

// Perl

Answer 1

The Java code is giving you URL-safe base64, i.e the output can be used in URLs. The Perl version is not. You can blindly replace the characters with the other values.