String xpathQuery1 =
"//" + sourcePinyinSystem.getTagName() + "[text()='" + pinyinString + "']";
Document pinyinMappingDoc = PinyinRomanizationResource.getInstance().getPinyinMappingDoc();
Element hanyuNode = pinyinMappingDoc.xpathSelectElement(xpathQuery1);
if (null != hanyuNode) {
// find the node of target Pinyin system
String xpathQuery2 = "../" + targetPinyinSystem.getTagName() + "/text()";
String targetPinyinStrWithoutToneNumber = hanyuNode.xpathSelectString(xpathQuery2);