You will need to walk every commit on the branch and wrap the output with the appropriate html tags. Now I understand you want to do it from jgit, so I'll provide an outline of how one would do it in a shell, and you will have to similarly invoke the rev-list
functionality of jgit‡:
#!/bin/sh
echo "<table style=\"width:300px\">"
for commit in $(git rev-list <your branch>); do
git log --format="<tr><td>%cr</td><td>%an</td><td>%s</td></tr>" $commit
done
echo "</table>"
For different formatting options visit the git-show
help pages.
‡ I haven't really checked that jgit supports rev-list, but the claim on the jgit web page, as I understand it, is that it support the git core functionality. For example - see org.eclipse.jgit.revwalk.