我有以下 rdf/xml 数据,我想获取元素的值,rtc_cm:Category即https://test.yahoo.com:9443/ccm/resource/itemOid/com.Category/_ivX6csaREeK41JJsvCkJ_A
<rdf:RDF>
  <rdf:Description rdf:about="https://server:9443/ccm/oslc/categories">
    <rdfs:member>
      <rtc_cm:Category rdf:about="https://server:9443/ccm/resource/itemOid/com.Category/_ivX6csaREeK41JJsvCkJ_A">
        <rtc_cm:hierarchicalName rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Test 2</rtc_cm:hierarchicalName>
      </rtc_cm:Category>
    </rdfs:member>
    <rdfs:member>
      <rtc_cm:Category rdf:about="https://server:9443/ccm/resource/itemOid/com.Category/_iV5DcMaREeK41JJsvCkJ_A">
        <rtc_cm:hierarchicalName rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Unassigned</rtc_cm:hierarchicalName>
      </rtc_cm:Category>
    </rdfs:member>
  </rdf:Description>
  <oslc:ResponseInfo rdf:about="https://server:9443/ccm/oslc/categories?oslc.select=rtc_cm:hierarchicalName&oslc.where=rtc_cm:projectArea=%22_fE-FT8aREeK41JJsvCkJ_A%22">
    <dcterms:title>Categories</dcterms:title>
    <oslc:totalCount>2</oslc:totalCount>
  </oslc:ResponseInfo>
</rdf:RDF>