Is there a Base64 library that is compatible with both Android and Java

Question

I have a common library that I use for both Java and Android projects and it requires a base64 encoder/decoder. The trouble is, the Apache commons library does not work with Android, at least not that I have been able to successfully implement - due to Android already implementing and earlier version and thus causing an error at run time whenever I attempt to encode or decode:

Base64.decodeBase64

Returns the error:

AndroidRuntime(1420): java.lang.NoSuchMethodError: org.apache.commons.codec.binary.Base64.decodeBase64

If anyone knows of a base64 library that is compatible with both Java and Android, or can explain to me how to get around the Apache commons issue, I would be very grateful. :^)

Answer 1

There's just "base64". It so trivial that you can google for any "java base64" and use any implementation.

EDIT

If you target pre API8, simply grab the source from Base64 implementation from API8 (it is android/util/Base64.java) and copy into your project.

Answer 2

Roll your own.

Here's decoding:

      static private int FromBase64Char(int c)
{
    if(c >= 'A' && c <= 'Z')
        return c - 'A';
    else if(c >= 'a' && c <= 'z')
        return c - 'a' + 26;
    else if(c >= '0' && c <= '9')
        return c - '0' + 52;
    else if(c == '+')
        return 62;
    else if(c == '/')
        return 63;
    else
        throw new IllegalArgumentException(); //Depends on how do you want to handle invalid characters
}


static public byte[] FromBase64(String s) throws IllegalArgumentException
{
    if(s == null)
        return null;

    int l = s.length();
    if(l == 0)
        return new byte[0];

    if(l % 4 != 0)
        throw new IllegalArgumentException();

    boolean Padded = (s.charAt(l-1) == '=');
    boolean Padded2 = (s.charAt(l-2) == '=');
    int ll = (Padded ? l-4 : l);
    int triad;

    byte [] b = new byte[(ll*3)/4 + (Padded ? (Padded2 ? 1 : 2) : 0)];

    int i, j = 0;
    for(i=0; i<ll; i+=4)
    {
        triad = 
            (FromBase64Char(s.charAt(i)) << 18) |
            (FromBase64Char(s.charAt(i+1)) << 12) |
            (FromBase64Char(s.charAt(i+2)) << 6) |
            FromBase64Char(s.charAt(i+3));

        b[j++] = (byte)((triad >> 16) & 0xff); 
        b[j++] = (byte)((triad >> 8) & 0xff);
        b[j++] = (byte)(triad & 0xff);
    }
    //The final chunk
    if(Padded)
    {
        if(Padded2) //Padded with two ='s
        {
            triad = (FromBase64Char(s.charAt(ll)) <<2 ) | (FromBase64Char(s.charAt(ll+1)) >> 4);
            b[j++] = (byte)triad;
        }
        else //Padded with one =
        {
            triad =
                (FromBase64Char(s.charAt(ll)) << 10) |
                (FromBase64Char(s.charAt(ll+1)) << 4) |
                (FromBase64Char(s.charAt(ll+2)) >> 2);  
            b[j++] = (byte)((triad >> 8) & 0xff);
            b[j++] = (byte)(triad & 0xff);
        }
    }
    return b;
}

And here's encoding:

private final static String BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
        PAD1 = "=", PAD2 = "==";

static public String ToBase64(final byte [] a)
{
    int l = a.length;
    StringBuilder sb = new StringBuilder((l+3)*4/3);
    int i;
    int mod = l % 3;
    int ll = l - mod;
    int triad;
    for(i=0;i<ll;i+=3)
    {
        triad = (a[i]<<16) | (a[i+1]<<8) | a[i+2];
        sb.append(BASE64_ALPHABET.charAt((triad >> 18) & 0x3f));
        sb.append(BASE64_ALPHABET.charAt((triad >> 12) & 0x3f));
        sb.append(BASE64_ALPHABET.charAt((triad >> 6) & 0x3f));
        sb.append(BASE64_ALPHABET.charAt(triad & 0x3f));
    }
    if(mod == 1)
    {
        sb.append(BASE64_ALPHABET.charAt((a[i] >> 2) & 0x3f));
        sb.append(BASE64_ALPHABET.charAt((a[i] << 4) & 0x3f));
        sb.append(PAD2);
    }
    if(mod == 2)
    {
        triad = (a[i]<<8) | a[i+1];
        sb.append(BASE64_ALPHABET.charAt((triad >> 10) & 0x3ff));
        sb.append(BASE64_ALPHABET.charAt((triad >> 4) & 0x3f));
        sb.append(BASE64_ALPHABET.charAt((triad << 2) & 0x3f));
        sb.append(PAD1);        
    }
    return sb.toString();   
}

Answer 3

In my application, I use jackson and it provides a base64 encoder/decoder, you can use it if your application use also Jackson.

import com.fasterxml.jackson.core.Base64Variants;

public class Foo {
    String encodeBase64(byte[] string) {
        return Base64Variants.getDefaultVariant().encode(string.getBytes());
    }
}