An XSD file is an XML file, so you can parse it using sax.
See :
http://java.sun.com/webservices/jaxp/dist/1.1/docs/tutorial/sax/2a_echo.html
http://java.sun.com/webservices/jaxp/dist/1.1/docs/tutorial/sax/work/Echo02.java
See also:
http://www.oracle.com/technology/tech/xml/xdk/doc/production/java/doc/java/javadoc/oracle/xml/parser/schema/XMLSchema.html#getXMLSchemaNodeTable