<p>Is there a built-in way to escape user input in java using the <code>JDBC</code>? Something similar to the php version <code>mysql_real_escape()</code> function. What's the best way to validate input?</p>

If you mean how do you make sure user input can't be used in SQL injection attacks, the way to do this (and the way all SQL should be written in JDBC) is using Prepared Statements. JDBC will automatically handle any necessary escaping.
http://java.sun.com/docs/books/tutorial/jdbc/basics/prepared.html