我有一個(gè)具有多個(gè)hpp:HourlyHistoricalPrice元素的XML文檔，如下所示：<?xml version="1.0"><hhp:HourlyHistoricalPrices xmlns:hhp="urn:or-HourlyHistoricalPrices">  <hhp:HourlyHistoricalPrice xmlns:hhp="urn:or-HourlyHistoricalPrice">    <hhp:indexId>1025127</hhp:indexId>    <hhp:resetDate>20161231T000000</hhp:resetDate>    <hhp:refSource>AIBO</hhp:refSource>    <hhp:indexLocation/>    <hhp:price1>50,870000</hhp:price1>    ...    <hhp:price48>43,910000</hhp:price48>  </hhp:HourlyHistoricalPrice>  <hhp:HourlyHistoricalPrice xmlns:hhp="urn:or-HourlyHistoricalPrice">    <hhp:indexId>1025127</hhp:indexId>    <hhp:resetDate>20160101T000000</hhp:resetDate>    <hhp:refSource>AIBO</hhp:refSource>    <hhp:indexLocation/>    <hhp:price1>51,870000</hhp:price1>    ...    <hhp:price48>49,910000</hhp:price48>  </hhp:HourlyHistoricalPrice>  <hhp:HourlyHistoricalPrice xmlns:hhp="urn:or-HourlyHistoricalPrice">    <hhp:indexId>1025127</hhp:indexId>    <hhp:resetDate>20163112T000000</hhp:resetDate>    <hhp:refSource>APX</hhp:refSource>    <hhp:indexLocation/>    <hhp:price1>63,870000</hhp:price1>    ...    <hhp:price48>29,910000</hhp:price48>  </hhp:HourlyHistoricalPrice>  </hhp:HourlyHistoricalPrices>我只想檢索hhp:HourlyHistoricalPrice具有特定值的節(jié)點(diǎn)hhp:refSource，例如AIBO。我正在嘗試下面的XPathExpression，但這什么也找不到。