Java REGEX XML解析/删减，同时保持结构HowTo

I am writing a RESTful web service in Java. The idea is to "cut down" an XML document and strip away all the unneeded content (~98%) and leave only the tags we're interested in, while maintaining the document's structure, which is as follows (I cannot provide the actual XML content for confidentiality reasons):I am writing a RESTful web service in Java. The