Random-Generate meaningless username [on hold]

I want to create a random username in a webservice, respecting following requirements:

1. It must not contain information about the user, e. g. no part of the name is allowed.
2. The user name must contain only easily distictible characters when printed, e. g. the confusion of 'l' and 'I' should be avoided.
3. It must be avoided, that the username contains any part with a possibly offensive meaning for the user, e. g. 'pig123f' or 'd1eXXX'.

If possible, can you please post a Java algorithm or hints to Java libraries that implement those?