You can very well do it with below code, i am giving you just the code to insert xml hope u are done with rest of other things..
import oracle.xdb.XMLType;
//now inside the class......
// this will be to convert xml into string
File file = new File(your file path);
FileReader fileR = new FileReader(file);
fileR.read(data);
String str = new String(data);
// now to enter it into db
conn = DriverManager.getConnection(serverName, userId, password);
XMLType objXml = XMLType.createXML(conn, str);
// inside the query statement put this code
objPreparedstatmnt.setObject(your value index, objXml);
I have done like this and it is working fine.