java DOMXpath获取属性值

我有以下xml：

<?xml version="1.0" encoding="UTF-8"?>
<GSP VER="3.2">
   <TM>0</TM>
   <Q>monkey pay</Q>
   <Context>
      <total_results>3</total_results>
   </Context>
   <RES EN="3" SN="1">
      <M>3</M>
      <R N="1">
         <U>link1</U>
         <T>title1</T>
         <S>snippet1</S>
      </R>
      <R N="2">
         <U>link2</U>
         <T>title2</T>
         <S>snippet2</S>
         <PageMap>
            <DataObject type="metatags">
               <Attribute name="viewport" value="width=992, maximum-scale=2.0" />
               <Attribute name="dc.subject" value="atributevalue" />
               <Attribute name="og:title" value="atributevalue" />
               <Attribute name="og:description" value="atributevalue" />
               <Attribute name="og:image" value="atributevalue" />
            </DataObject>
            <DataObject type="cse_image">
               <Attribute name="src" value="atributevalue" />
            </DataObject>
            <DataObject type="cse_thumbnail">
               <Attribute name="width" value="atributevalue" />
               <Attribute name="height" value="atributevalue" />
               <Attribute name="src" value="image2" />
            </DataObject>
         </PageMap>
      </R>
      <R N="3">
         <U>link3</U>
         <T>title3</T>
         <S>snippet3</S>
      </R>
   </RES>
</GSP>

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我不知道为什么它不起作用。 那么标准java实现呢：

XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("your path");

XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("your path");