I believe in the Java example you should be applying .getBytes("UTF-8") to the plaintext string; not to the digest. This is because Java strings are UTF-16.

The following two programs both seem to output the same MD5 sum...

use Digest::MD5 'md5_hex';
use Math::BigInt;

my $plain  = "abcd1234";
my $digest = Math::BigInt::->from_hex(md5_hex $plain);
print $digest, "\n";
[download]

(Run the above using perl hash.pl.)

import java.security.MessageDigest;
import java.math.BigInteger;

public class Hash
{
    public static void main( String[] args ) throws Exception
    {
        MessageDigest md5    = MessageDigest.getInstance("MD5");
        String        plain  = "abcd1234";
        BigInteger    digest = new BigInteger(1, md5.digest(plain.getB
+ytes("UTF-8")));
        
        System.out.println( digest.abs() );
    }
}
[download]

(Run the above using javac Hash.java && java -cp . Hash.)

Thank you! definitely two programs both seem to output the same MD5 sum
-----------------------------------------------------------
Java
String plain = "abcd1234";
BigInteger digest = new BigInteger(1, md5.digest(plain.getB +ytes("UTF-8")));

Perl
my $plain = "abcd1234";
my $digest = Math::BigInt::->from_hex(md5_hex $plain);
-----------------------------------------------------------

But i want something different
-----------------------------------------------------------
Java
String plain = "abcd1234";
BigInteger digest = new BigInteger(md5.digest(plain.getB +ytes("UTF-8")));

Perl
my $plain = "abcd1234";
my $digest = Math::BigInt::->from_hex(md5_hex $plain);
-----------------------------------------------------------
its two programs output diffrent MD5 sum.. my $digest = Math::BigInt::->from_hex(md5_hex $plain);　<--
　

The one argument form of the Java BigInteger constructor assumes you're passing in a binary two's complement integer.

Math::BigInt doesn't have a two's complement constructor. You'd need to write one.

package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name