Java (or other) based Keyword/URL Content Filtering

Java (or other) based Keyword/URL Content Filtering

Please be gentle! I have a severely autistic son and need a better way to
filter content that he receives via web browsers. OpenDns etc are too
broad a brush.
Looking for advice mainly around the language to use to attempt such a
project. I am a once upon a time developer who had a massive life changing
experience (see above) and whatever I try and do this in it will be
starting from scratch again. JAVA would be useful as I have some
rudimentary knowledge, but if the consensus is that this is not possible
or foolish then happy to try another way.
I understand that for me this is a long term project with a large learning
curve. I understand the "networking" aspects of this so really looking to
focus down to what language to use.
Many thanks to any who respond.