将 MD5 - base64 从 JAVA 转换为 PHP

Question

I have a problem converting this Java code that generate md5-base64 to php.

I'd try more then 5 hours but without success.

This is the java code:

public static void main(String[] args) {
        // TODO code application logic here

        try {
            String string = "customString";
            String format = "20190101000000";
            StringBuilder sb = new StringBuilder();
            sb.append(format);
            sb.append(string);
            String sb2 = sb.toString();

            byte[] bytes = sb2.getBytes();
            byte[] bArr = new byte[16];
            MessageDigest instance2 = MessageDigest.getInstance("MD5");
            instance2.update(bytes, 0, bytes.length);
            instance2.digest(bArr, 0, 16);

            PrintStream printStream6 = System.out;
            String a2 = Base64.getEncoder().encodeToString(bArr);
            if (a2.length() >= 20) {
                a2 = a2.substring(0, 19).trim();
            }
            StringBuilder sb8 = new StringBuilder();
            sb8.append("MD5 16: ");
            sb8.append(a2);
            printStream6.println(sb8.toString());

        } catch (Exception e) {
            System.out.println(e);
        }

    }

And this is my php

<?php

$string = 'customString';
$format = '20190101000000';

$res = $format . $string;
$md5 = md5($res, true);
echo $md5;
echo '------------------';

$base = base64_encode($md5);
echo $base;
echo '------------------';

$result = substr($base, 0, 19);
echo $result;
echo '------------------';

The Java result is 1B2M2Y8AsgTpgAmY7Ph and php is iSKxA+7Y1mMnHhwf0yb

Answer 1

Check for charset encodings. In Java Strings are usually UTF-8 encoded. But when you transform to byte[] in sb2.getBytes(); it is using platform default charset (eg ISO-8859-1).

You have to provide the charset in java to have a determined behavior:

sb2.getBytes(java.nio.charset.Charset.forName("UTF-8");

or, the other way round, if goal isn't simply to make both reproduce same output, but you have to implement a PHP solution compatible with your existing Java solution, convert the PHP UTF-8 string to correct charset before md5(...). Therefore use iconv method.