Is JDBC multi-threaded insert possible?
Multi-threading isn't going to help you here. You'll just move the contention bottleneck from your app server to the database.
Instead, try using batch-inserts instead, they generally make this sort of thing orders of magnitude faster. See "3.4 Making Batch Updates" in the JDBC tutorial.
Edit: As @Jon commented, you need to decouple the fetching of the web pages from their insertion into the database, otherwise the whole process will go at the speed of the slowest operation. You could have multiple threads fetching web pages, which add the data to a queue data structure, and then have a single thread draining the queue into the database using a batch insert.
Just make sure two (or more) threads doesn't use the same connection at the same time, using a connection pool resolves that. c3po and apache dbcp comes to mind ...
You can insert these records in different threads provided they do use different primary key values.
You should also look at Spring Batch which I believe will be useful in your case.