My colleagues and I recently do more investigation, we found the two alternatives for the byte array to string and vice versa:

1. sun.misc.BASE64Decoder and sun.misc.BASE64Encoder. But that was not officially supportted by SUN.

2. MigBase64 http://migbase64.sourceforge.net/.

Right now the MigBase64 is the fastest solution for this area. And detail bechmarch please check the url: http://migbase64.sourceforge.net/

So here means if you had direction, you could find any fastest solutions for you references.

The results is:

Example StringLength:6291456

HEX encoder  time:421371431 nano seconds

HEX decoder  time:257492503 nano seconds

Encoded StringLength:6291456

sun.misc.BASE64  encode time:258552414 nano seconds

sun.misc.BASE64  decode time:359357404 nano seconds

Encoded StringLength:4304680

MigBASE64 encode  time:49359904 nano seconds

MigBASE64 decode  time:67830130 nano seconds

Encoded StringLength:4304680

So you can see the average time for MigBase64 6 times faster than SunBase64 and 10 times faster than my proposed yesterday.