我正在遍历this webpage处的所有数据（下面的示例xml），我对如何获得所需的值感到困惑。
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet title="XSL_formatting" type="text/xsl" href="/i/xml/xsl_formatting_rss.xml"?>
<rss xmlns:blogChannel="http://backend.userland.com/blogChannelModule" version="2.0">
<channel>
<title>Ariana Resources News</title>
<link>http://www.iii.co.uk/investment/detail?code=cotn:AAU.L&display=news</link>
<description />
<item>
<title>Ariana Resources PLC - Environmental Impact Assessment Submitted for Kiziltepe</title>
<link>http://www.iii.co.uk/investment/detail?code=cotn:AAU.L&display=news&action=article&articleid=9084833&from=rss</link>
<description>Some Article information</description>
<pubDate>Fri, 30 Aug 2013 07:00:00 GMT</pubDate>
</item>
<item>
<title>Ariana Resources PLC - Directors' Dealings and Holding in Company</title>
<link>http://www.iii.co.uk/investment/detail?code=cotn:AAU.L&display=news&action=article&articleid=9053338&from=rss</link>
<description>Some Article information</description>
<pubDate>Wed, 31 Jul 2013 07:00:00 GMT</pubDate>
</item>
<item>
<title>Ariana Resources PLC - Directorship Changes</title>
<link>http://www.iii.co.uk/investment/detail?code=cotn:AAU.L&display=news&action=article&articleid=9046582&from=rss</link>
<description>Some Article information</description>
<pubDate>Wed, 24 Jul 2013 09:31:00 GMT</pubDate>
</item>
<item>
<title>Ariana Resources PLC - Ariana Resources plc : Capital Reorganisation</title>
<link>http://www.iii.co.uk/investment/detail?code=cotn:AAU.L&display=news&action=article&articleid=9038706&from=rss</link>
<description>Some Article information</description>
<pubDate>Wed, 24 Jul 2013 09:31:00 GMT</pubDate>
</item>
<item>
</channel>
</rss>
我已经看过dom4j快速入门指南了，虽然我怀疑我不太明白。
我怎样才能以这样的方式进行迭代：
此时我已经得到了以下内容，我认为在第二次循环中这是非常错误的...非常感谢任何帮助：
//Create a null Document Object
Document theXML = null;
//Get the document of the XML and assign to Document object
theXML = parseXML(url);
//Place the root element of theXML into a variable
Element root = theXML.getRootElement();
// iterate through child elements of root
for ( Iterator i = root.elementIterator(); i.hasNext(); ) {
Element element = (Element) i.next();
// do something
// iterate through child elements of root with element name "item"
for ( Iterator j = root.elementIterator( "item" ); j.hasNext(); ) {
Element foo = (Element) j.next();
String rnsHeadline = "";
String rnsLink = "";
String rnsFullText = "";
String rnsConstituentName = "";
Rns rns = new Rns(null, null, null, null);
}
答案 0 :(得分：2)
使用dom4j的XPath功能：
// Place the root element of theXML into a variable
List<? extends Node> items =
(List<? extends Node>)theXML.selectNodes("//rss/channel/item");
// RFC-dictated date format used with RSS
DateFormat dateFormatterRssPubDate =
new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z", Locale.ENGLISH);
// today started at this time
DateTime timeTodayStartedAt = new DateTime().withTimeAtStartOfDay();
for (Node node: items) {
String pubDate = node.valueOf( "pubDate" );
DateTime date = new DateTime(dateFormatterRssPubDate.parse(pubDate));
if (date.isAfter(timeTodayStartedAt)) {
// it's today, do something!
System.out.println("Today: " + date);
} else {
System.out.println("Not today: " + date);
}
}
Dom4j需要jaxen依赖才能使XPath正常工作。我使用JodaTime来比较日期，因为它比使用java内置日期更清晰。 Here's the full example
请注意，dom4j并未真正维护，因此您可能也对this discussion about dom4j alternatives感兴趣。
答案 1 :(得分：0)
第二个循环没有任何问题，你必须在元素层次结构中导航才能进入你感兴趣的东西，所以你已经在正确的道路上了。以下是您可以继续的方式：
public class Dom4JRssParser {
private void parse(Date day) throws DocumentException, ParseException {
Date dayOnly = removeTime(day);
// Fri, 30 Aug 2013 07:00:00 GMT
SimpleDateFormat sdfXml = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", Locale.ENGLISH);
System.out.println("Day: " + sdfXml.format(dayOnly));
SAXReader reader = new SAXReader();
Document doc = reader.read(getClass().getResourceAsStream("/com/so/dom4j/parser/rss/example_01.xml"));
Element root = doc.getRootElement(); // rss
for(Iterator rootIt = root.elementIterator("channel"); rootIt.hasNext(); ) {
Element channel = (Element) rootIt.next();
for(Iterator itemIt = channel.elementIterator("item"); itemIt.hasNext(); ) {
Element item = (Element) itemIt.next();
Element pubDate = item.element("pubDate");
if(pubDate != null) {
if(removeTime(sdfXml.parse(pubDate.getTextTrim())).equals(dayOnly)) {
Rns rns = new Rns(item.element("title"),
item.element("link"),
item.element("description"),
item.element("constituent"));
System.out.println(rns.toString());
System.out.println();
}
}
}
}
}
private Date removeTime(Date day) {
Calendar c = Calendar.getInstance(Locale.ENGLISH);
c.setTime(day);
c.set(Calendar.HOUR_OF_DAY, 0);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
c.set(Calendar.MILLISECOND, 0);
return c.getTime();
}
public static void main(String... args) throws ParseException, DocumentException {
Dom4JRssParser o = new Dom4JRssParser();
if(args.length == 0) {
o.parse(new Date());
} else {
SimpleDateFormat sdfInput = new SimpleDateFormat("yyyyMMdd");
for(String arg : args) {
o.parse(sdfInput.parse(arg));
}
}
}
}
使用参数
进行测试运行20130731
<强>输出
Day: Wed, 31 Jul 2013 00:00:00 CEST
Rns [rnsHeadline=Ariana Resources PLC - Directors' Dealings and Holding in Company
rnsLink=http://www.iii.co.uk/investment/detail?code=cotn:AAU.L&display=news&action=article&articleid=9053338&from=rss
rnsFullText=Some Article information
rnsConstituentName=]
另外，您可以考虑使用XPath API（您发布的快速入门链接中的Powerful Navigation with XPath部分），因为它更舒服，请参阅eis的回答。