这将向您展示如何
将XML文件读入DOM
用XPath过滤出一组节点
对每个提取的节点执行特定的操作。
我们将用下面的语句调用代码
processFilteredXml(xmlIn, xpathExpr,(node) -> {/*Do something...*/;});
在本例中，我们希望从book.xml中打印一些creatorName，使用"//book/creators/creator/creatorName"作为xpath，在每个匹配xpath的节点上执行printNode操作。
完整代码
@Test
public void printXml() {
try (InputStream in = readFile("book.xml")) {
processFilteredXml(in, "//book/creators/creator/creatorName", (node) -> {
printNode(node, System.out);
});
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private InputStream readFile(String yourSampleFile) {
return Thread.currentThread().getContextClassLoader().getResourceAsStream(yourSampleFile);
}
private void processFilteredXml(InputStream in, String xpath, Consumer<Node> process) {
Document doc = readXml(in);
NodeList list = filterNodesByXPath(doc, xpath);
for (int i = 0; i < list.getLength(); i++) {
Node node = list.item(i);
process.accept(node);
}
}
public Document readXml(InputStream xmlin) {
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
return db.parse(xmlin);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private NodeList filterNodesByXPath(Document doc, String xpathExpr) {
try {
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xpath = xPathFactory.newXPath();
XPathExpression expr = xpath.compile(xpathExpr);
Object eval = expr.evaluate(doc, XPathConstants.NODESET);
return (NodeList) eval;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private void printNode(Node node, PrintStream out) {
try {
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
StreamResult result = new StreamResult(new StringWriter());
DOMSource source = new DOMSource(node);
transformer.transform(source, result);
String xmlString = result.getWriter().toString();
out.println(xmlString);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
打印
<creatorName>Fosmire, Michael</creatorName>
<creatorName>Wertz, Ruth</creatorName>
<creatorName>Purzer, Senay</creatorName>
对于book.xml
<book>
<creators>
<creator>
<creatorName>Fosmire, Michael</creatorName>
<givenName>Michael</givenName>
<familyName>Fosmire</familyName>
</creator>
<creator>
<creatorName>Wertz, Ruth</creatorName>
<givenName>Ruth</givenName>
<familyName>Wertz</familyName>
</creator>
<creator>
<creatorName>Purzer, Senay</creatorName>
<givenName>Senay</givenName>
<familyName>Purzer</familyName>
</creator>
</creators>
<titles>
<title>Critical Engineering Literacy Test (CELT)</title>
</titles>
</book>
