我是xml解析的新手,但我必须从特定的URL获取XML,然后只保存一个资源。
我如何获得xml:
public Document getXMLFile(String urlToXml) {
try {
URL url = new URL(urlToXml);
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.parse(url.openStream());
return document;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
}
return null;
}
这完美无缺,并且返回了这个文件:
<CRates xmlns="****" xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="******">
<Date>20161003</Date>
<Currencies>
<Currency>
<ID>AUD</ID>
<Rate>1.46380</Rate>
</Currency>
<Currency>
<ID>BGN</ID>
<Rate>1.95580</Rate>
</Currency>
<Currency>
<ID>BRL</ID>
<Rate>3.64090</Rate>
</Currency>
<Currency>
<ID>CAD</ID>
<Rate>1.47020</Rate>
</Currency>
<Currency>
<ID>CHF</ID>
<Rate>1.09180</Rate>
</Currency>
<Currency>
<ID>CNY</ID>
<Rate>7.49620</Rate>
</Currency>
<Currency>
<ID>CZK</ID>
<Rate>27.02100</Rate>
</Currency>
<Currency>
<ID>DKK</ID>
<Rate>7.44630</Rate>
</Currency>
<Currency>
<ID>GBP</ID>
<Rate>0.87318</Rate>
</Currency>
<Currency>
<ID>HKD</ID>
<Rate>8.71450</Rate>
</Currency>
<Currency>
<ID>HRK</ID>
<Rate>7.50530</Rate>
</Currency>
<Currency>
<ID>HUF</ID>
<Rate>308.18000</Rate>
</Currency>
<Currency>
<ID>IDR</ID>
<Rate>14587.14000</Rate>
</Currency>
<Currency>
<ID>ILS</ID>
<Rate>4.22280</Rate>
</Currency>
<Currency>
<ID>INR</ID>
<Rate>74.76600</Rate>
</Currency>
<Currency>
<ID>JPY</ID>
<Rate>113.90000</Rate>
</Currency>
<Currency>
<ID>KRW</ID>
<Rate>1237.21000</Rate>
</Currency>
<Currency>
<ID>MXN</ID>
<Rate>21.61500</Rate>
</Currency>
<Currency>
<ID>MYR</ID>
<Rate>4.62720</Rate>
</Currency>
<Currency>
<ID>NOK</ID>
<Rate>8.96250</Rate>
</Currency>
<Currency>
<ID>NZD</ID>
<Rate>1.54540</Rate>
</Currency>
<Currency>
<ID>PHP</ID>
<Rate>54.17900</Rate>
</Currency>
<Currency>
<ID>PLN</ID>
<Rate>4.29330</Rate>
</Currency>
<Currency>
<ID>RON</ID>
<Rate>4.45050</Rate>
</Currency>
<Currency>
<ID>RUB</ID>
<Rate>70.00100</Rate>
</Currency>
<Currency>
<ID>SEK</ID>
<Rate>9.59300</Rate>
</Currency>
<Currency>
<ID>SGD</ID>
<Rate>1.53260</Rate>
</Currency>
<Currency>
<ID>THB</ID>
<Rate>38.91000</Rate>
</Currency>
<Currency>
<ID>TRY</ID>
<Rate>3.38610</Rate>
</Currency>
<Currency>
<ID>USD</ID>
<Rate>1.12360</Rate>
</Currency>
<Currency>
<ID>ZAR</ID>
<Rate>15.26410</Rate>
</Currency>
</Currencies>
</CRates>
问题是 - 如何从所有这些东西中只获得一个指定节点(例如USD)并将其保存为新的xml?
输出xml的示例:
<CRates>
<Date>20160321</Date>
<ID>USD</ID>
<Rate>1.12360</Rate>
</Currency>
</CRates>
感谢您的帮助,
干杯
答案 0 :(得分:3)
一种方法是使用XPaths来匹配所需的节点。
import javax.xml.xpath.*;
...
XPathFactory xpathFactory = XPathFactory.newInstance();
XPath xpath = xpathFactory.newXPath();
NodeList nodes = (NodeList) xpath.evaluate("//*[@id='USD']", document, XPathConstants.NODESET);
如果您确定只有一个节点需要查找,XPath.evaluate也可以返回单个Element对象,但此版本的NodeLists将能够处理返回多个节点的情况。