If you want to deal with XMLTYPE in JDBC code then you will have to use Oracle driver's extension -
XMLType xml = XMLType.createXML(resultSet.getOPAQUE("xmlColumn"));
There are multiple ways to deal with XMLType in your JDBC code. One is to use Oracle Specific extension as above, You can also use JAVA DOM API with Oracle extension. You can find enough examples in online documentation.
Other simple way to avoid Oracle specific extensions would be to make your stored procedure return CLOB or
String for XMLType.
The Select statement in SP would look like
SELECT e.xmlColumn.getStringVal() from table e -- for String
SELECT e.xmlColumn.getClobVal() from table e -- for Clob