为子节点解析JDOM中的XML文件
[英]Parsing an XML file in JDOM for child-child nodes
问题描述
I have an XML file in the following manner: 
我有以下方式的XML文件：
<head>
<username>bhnsub</username>
<error>0</error>
<account_id>633</account_id>
<info>
<mac>address_goes_here<mac>
<mac>address_goes_here</mac>
<mac>address_goes_here</mac>
<mac>address_goes_here</mac>
<mac>address_goes_here<mac>
</info>
</head>
I need to parse it using Java DOM parser and get the corresponding values. 我需要使用Java DOM解析器解析它并获取相应的值。 I need to put the values under info in a list. 我需要将值放在info下的列表中。
SAXBuilder builder = new SAXBuilder();
Document document = (Document) builder.build(new StringReader(content));
Element rootNode = document.getRootElement();
if (rootNode.getName().equals("head")) {
String username = rootNode.getChildText("username");
String error= rootNode.getChildText("error");
String account= rootNode.getChildText("account_id");
Element info= rootNode.getChildren("info");
List mac=info.getChildren("mac");
I am not getting how to proceed further and use the list. 我不知道如何继续进行和使用列表。
2 个解决方案
解决方案1
0 2015-10-08 10:00:50
This works, using stuff from javax.xml.parsers and org.w3c.dom. 这可以使用javax.xml.parsers和org.w3c.dom中的内容进行工作。
List<String> macvals = new ArrayList<>();
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = db.parse(new File( "head.xml" ) );
Element rootNode = document.getDocumentElement();
if (rootNode.getTagName().equals("head")) {
NodeList infos = rootNode.getElementsByTagName("info");
if( infos.getLength() > 0 ){
Element info = (Element)infos.item(0);
NodeList macs = info.getElementsByTagName("mac");
for( int i = 0; i < macs.getLength(); ++i ){
macvals.add( macs.item( i ).getTextContent() );
}
}
}
System.out.println( macvals );
解决方案2
0 已采纳 2015-10-08 10:21:55
First up, please ensure you are using JDOM 2.0.6 (or later if you are reading this in the future). 首先，请确保您使用的是JDOM 2.0.6（或更高版本，如果将来要阅读的话）。 JDOM 2.x has been out for 5 years or so, and is better because it supports Java generics, it has performance improvements, and it has better XPath support too, if you need it. JDOM 2.x已经问世5年了，它更好，因为它支持Java泛型，具有性能改进，并且如果需要，它也具有更好的XPath支持。
Still, your code would be "easily" written as: 尽管如此，您的代码仍将“轻松”编写为：
SAXBuilder builder = new SAXBuilder();
Document document = builder.build(new StringReader(content));
Element rootNode = document.getRootElement();
if ("head".equals(rootNode.getName())) {
String username = rootNode.getChildText("username");
String error= rootNode.getChildText("error");
String account= rootNode.getChildText("account_id");
List<String> macs = new ArrayList<>();
for (Element info : rootNode.getChildren("info")) {
for (Element mac : info.getChildren("mac")) {
macs.add(mac.getValue());
}
}
}
Note that I have put 2 loops in there. 请注意，我在其中放置了2个循环。 Your code has a bug, because it calls: 您的代码有一个错误，因为它调用：
Element info = rootNode.getChildren("info");
but getChildren(...) returns a List, so that can't work. 但是getChildren(...)返回一个List，因此无法正常工作。 In my code above I iterate through the list instead. 在上面的代码中，我改为遍历该列表。 If there is only one "info" element, then the list will have only one member. 如果只有一个“ info”元素，则列表将只有一个成员。
Also note that, in JDOM 2.x, the getChildren(..) method returns a list of Element: List<Element> so there is no need to cast the results to Element . 还要注意，在JDOM 2.x中， getChildren(..)方法返回Element的列表： List<Element>因此无需将结果转换为Element 。
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