Xpath没有给出正确的结果

Question

我有一个xml文件，我用XPATH解析它。但我同时获得内容出来的

这里有问题是XML

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?> 
<reg> 
    <user> 
    <Name>abc def</Name> 
    <Email>ahjkhjkghjkhjk</Email> 
    <Picture>/mnt/sdcard/download/1357670177a386a-big-1.jpg</Picture> 
    <LastEdited>Mar 12, 2014 10:32:09 AM</LastEdited> 
    </user> 
    <user> 
    <Name>xy zabc</Name> 
    <Email>asdasdasdasd</Email> 
    <Picture>/mnt/sdcard/download/1357670177a386a-big-1.jpg</Picture> 
    <LastEdited>Mar 12, 2014 10:32:09 AM</LastEdited> 
    </user> 
    </reg> 

，这里是我的代码用于解析它

DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance(); 

DocumentBuilder builder = builderFactory.newDocumentBuilder(); 

Document xmlDocument = builder.parse(file); 

XPath xPath = XPathFactory.newInstance().newXPath(); 


String expression = "/reg/user/Name"; 
System.out.println(expression); 

NodeList nodeList = (NodeList) xPath.compile(expression).evaluate(xmlDocument, XPathConstants.NODESET); 
for (int i = 0; i < nodeList.getLength(); i++) { 
    System.out.println(nodeList.item(i).getFirstChild().getNodeValue()); 
    Users_List.add(nodeList.item(i).getFirstChild().getNodeValue()); 
} 

这种表达"reg/user"它返回任何结果和"reg/user/Name"或"reg/user/Email"它会返回正确的结果。我已经用在线测试器测试了表达式，它给出了正确的结果。有我的解析代码蚂蚁问题..？

Answer 1

您的每个user元素的第一个子元素都是空的文本节点，因此您的println语句可能只是不打印任何内容。这给一试：

for (int i = 0; i < nodeList.getLength(); i++) { 
    System.out.println(nodeList.item(i).getChildNodes()[1].getTextContent()); 
    Users_List.add(nodeList.item(i).getChildNodes()[1].getTextContent()); 
} 

尽管这可能是更好的：

for (int i = 0; i < nodeList.getLength(); i++) { 
    String name = ""; 
    NodeList nameList = (NodeList)xPath.evaluate("Name", nodeList.items(i), 
                XPathConstants.NODE); 
    if(nameList.getLength() > 0) { 
     name = nameList.items(0).getTextContent(); 
    } 
    System.out.println(name); 
    Users_List.add(name); 
}