InputStreamReader reader = new InputStreamReader(
new FileInputStream("input_xml"), "UTF-8");
Source xmlSource = new StreamSource(reader);
System.out.println("reader encoding == " + reader.getEncoding());
Source xsltSource = new StreamSource(new InputStreamReader(
new FileInputStream("input_xsl"), "UTF-8"));
// Create a transform factory instance.
TransformerFactory tfactory = TransformerFactoryImpl.newInstance();
OutputStreamWriter writer = new OutputStreamWriter(
new FileOutputStream("output_xml"), "UTF-8");
Result result = new StreamResult(writer);
// Create a transformer for the stylesheet.
Transformer transformer = tfactory.newTransformer(xsltSource);
// Transform the source XML to System.out.
But the functionality of matches is not working...
 The path is an absolute path, hence, the return (sequence) is independent of the context node within the xslt. Make sure that's what is original intention.
 The line as such would be a correct line if and only if the path returns either an empty sequence or a sequence with one item only, otherwise, it would be a runtime error. If it is empty sequence, the match will return false and it is not an error.
 Since it is an absolute path, it is not clear which node, if any, would be targetted to be tested. Suppose it is intended to test only the first entry, if any, the proper line would look like this.
 If the pattern matches any "substring" within the text, the function would return true, otherwise, false.
ps: Just a side note: the in-params have not been put into good use in myTransformer. I suppose it is work-in-progress.