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我正在遍历此网页上的所有数据（下面的示例 xml），我对如何获取所需值感到困惑。

<?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&amp;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&amp;display=news&amp;action=article&amp;articleid=9084833&amp;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&amp;display=news&amp;action=article&amp;articleid=9053338&amp;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&amp;display=news&amp;action=article&amp;articleid=9046582&amp;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&amp;display=news&amp;action=article&amp;articleid=9038706&amp;from=rss</link>
        <description>Some Article information</description>
        <pubDate>Wed, 24 Jul 2013 09:31:00 GMT</pubDate>
    </item>
    <item>
</channel>
</rss>

我看过dom4j快速入门指南，虽然我怀疑我只是不太明白。

我怎样才能以这样的方式进行迭代：

  1. 如果它有今天的日期，请浏览每个...
  2. 获取每个 specificall 的值，以及

在这一点上，我得到了以下内容，我认为在第二个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);

        }
4

2 回答 2

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 工作。我使用JodaTime来比较日期，因为它比使用 java 内置日期要干净得多。这是完整的例子。

请注意，dom4j 并没有真正维护，因此您可能也对有关 dom4j 替代品的讨论感兴趣。

于 2013-09-07T14:33:48.983 回答
0

第二个循环没有任何问题，您必须浏览元素层次结构才能到达您感兴趣的位置，因此您已经走上了正确的道路。以下是您可以继续的方法：

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));
            }
        }
    }
}

使用参数测试运行

20130731

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=]

您也可以考虑使用XPath API（Powerful Navigation with XPath您发布的快速启动链接中的部分），因为它更舒适，请参阅 eis 的答案。

于 2013-09-07T14:56:04.907 回答