我试图通过获取所有“<Type>
”元素来解析URL中的XML文件,其中参数type_id =“4218”??
XML文档:
<BSQCUBS Version="0.04" Date="Fri Dec 9 11:43:29 GMT 2011" MachineDate="Fri, 09 Dec 2011 11:43:29 +0000">
<Class class_id="385">
<Title>Football Matches</Title>
<Type type_id="4264" type_minbet="0.1" type_maxbet="2000.0">
...
</Type>
<Type type_id="5873" type_minbet="0" type_maxbet="0">
...
</Type>
<Type type_id="4725" type_minbet="0.1" type_maxbet="2000.0">
...
</Type>
<Type type_id="4218" type_minbet="0.1" type_maxbet="2000.0">
...
</Type>
<Type type_id="4221" type_minbet="0.1" type_maxbet="2000.0">
...
</Type>
<Type type_id="4218" type_minbet="0.1" type_maxbet="2000.0">
...
</Type>
<Type type_id="4299" type_minbet="0.1" type_maxbet="2000.0">
...
</Type>
</Class>
</BSQCUBS>
这是我的Java代码:
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new URL("http://cubs.bluesq.com/cubs/cubs.php?action=getpage&thepage=385.xml").openStream());
doc.getDocumentElement().normalize();
NodeList nodeList = doc.getElementsByTagName("Type");
System.out.println("ukupno:"+nodeList.getLength());
if (nodeList != null && nodeList.getLength() > 0) {
for (int j = 0; j < nodeList.getLength(); j++) {
Element el = (org.w3c.dom.Element) nodeList.item(j);
type_id = Integer.parseInt(el.getAttribute("type_id"));
System.out.println("type id:"+type_id);
}
}
这段代码给了我所有元素,我不希望这样,我想要属性type_id =“4218”的所有元素!
答案 0 :(得分:28)
XPath是您的正确选择:
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse("<Your xml doc uri>");
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("//Type[@type_id=\"4218\"]");
NodeList nl = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
迭代nl
答案 1 :(得分:7)
你在循环中错过了一个条件:
if(nodeList != null && nodeList.getLength() > 0){
for (int j = 0; j < nodeList.getLength(); j++) {
Element el = (org.w3c.dom.Element) nodeList.item(j);
if (el.hasAttribute("type_id") && el.getAttribute("type_id").equals("4218")) {
type_id = Integer.parseInt(el.getAttribute("type_id"));
System.out.println("type id:"+type_id);
}
}
}
此外,您不需要测试getElementsByTagName返回的NodeList是否为null,因此您可以在循环之前删除if。
一般情况下,使用XPath可能会更好。
答案 2 :(得分:5)
您可以使用XPath.XPath用于浏览XML文档中的元素和属性。在Java中有一些很好的Xpath实现。
对于你的例子
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xpath.compile("//Type[@type_id=\"4218\"]");
Object exprResult = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodeList = (NodeList) exprResult;
答案 3 :(得分:3)
按照下面的@soulcheck回答,如果可能的话,请提供一个中断声明......这可以增强您的搜索效果。
if(nodeList != null && nodeList.getLength() > 0){
for (int j = 0; j < nodeList.getLength(); j++) {
Element el = (org.w3c.dom.Element) nodeList.item(j);
if (el.hasAttribute("type_id") && el.getAttribute("type_id").equals("4218")) {
type_id = Integer.parseInt(el.getAttribute("type_id"));
System.out.println("type id:"+type_id);
break;
}
}
}
答案 4 :(得分:2)
以下XPath将为您提供您所追求的Type元素:
/BSQCUBS/Class/Type[@type_id=4218]
因此,您可以使用以下Java代码来获取仅包含以下内容的NodeList:
XPathExpression expr = xpath.compile("/BSQCUBS/Class/Type[@type_id=4218]");
NodeList nl = (NodeList)expr.evaluate(doc, XPathConstants.NODESET);