使用XPath处理XML文件生成的路径时出错
作者：互联网
我有XML文件,我试图使用XPath获取其路径的所有值,但它不会为NameSpaces生成值,如：
//rss/channel/item/yweather:forecast/@low
要么
//rss/channel/yweather:wind/text()
代码 ：
使用的方法：
public class XmlSource{
private XPathFactory factory = XPathFactory.newInstance();
private XPath xpath = factory.newXPath();
public Map<String, Object> update(String XML) throws ParserConfigurationException, SAXException, IOException, XPathExpressionException, TransformerException{
XmlSource xml = new XmlSource();
Map<String, Object> result = new HashMap<String, Object>();
Document doc = convert(XML); // converting the String to a document (tested and working efficiently)
xml.doc = doc;
xpath.setNamespaceContext(new NamespaceResolver(xml.doc));
ArrayList<String> paths = xml.getAllPaths(); // to get the listed above paths (tested and working efficiently)
for(int i=0; i < paths.size() ; i++){
result.put(paths.get(i), getValue(paths.get(i), xml.doc));
}
return result;
}
public String getValue(String path, Document doc) throws TransformerException, IOException, ParserConfigurationException, SAXException {
this.doc = doc;
try {
XPathExpression expr = xpath.compile(path);
Object result = expr.evaluate(this.doc, XPathConstants.STRING);
return result.toString();
} catch (XPathExpressionException ex) {
return null;
}
}
}
NamespaceResolver类：
import java.util.Iterator;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import org.w3c.dom.Document;
public class NamespaceResolver implements NamespaceContext {
private Document sourceDocument;
public NamespaceResolver(Document document) {
sourceDocument = document;
}
@Override
public String getNamespaceURI(String prefix) {
if (prefix.equals(XMLConstants.DEFAULT_NS_PREFIX)) {
return sourceDocument.lookupNamespaceURI(null);
} else {
return sourceDocument.lookupNamespaceURI(prefix);
}
}
@Override
public String getPrefix(String namespaceURI) {
return sourceDocument.lookupPrefix(namespaceURI);
}
@Override
public Iterator<String> getPrefixes(String namespaceURI) {
return null;
}
}
抛出异常：
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
--------------- linked to ------------------
javax.xml.xpath.XPathExpressionException
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
//rss/channel/item/yweather:condition/@text
//rss/channel/item/yweather:forecast/@code
//rss/channel/item/yweather:forecast/@date
//rss/channel/item/yweather:forecast/@day
//rss/channel/item/yweather:forecast/@high
//rss/channel/item/yweather:forecast/@low
//rss/channel/item/yweather:forecast/@text
//rss/channel/item/yweather:forecast/@code
//rss/channel/item/yweather:forecast/@date
//rss/channel/item/yweather:forecast/@day
//rss/channel/item/yweather:forecast/@high
//rss/channel/item/yweather:forecast/@low
//rss/channel/item/yweather:forecast/@text
--------------- linked to ------------------
javax.xml.xpath.XPathExpressionException
dAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: com.sun.org.apache.xpath.internal.domapi.XPathStylesheetDOM3Exception: Prefix must resolve to a namespace: yweather
at com.sun.org.apache.xpath.internal.compiler.XPathParser.errorForDOM3(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.Lexer.mapNSTokens(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.Lexer.tokenize(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.Lexer.tokenize(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.initXPath(Unknown Source)
at com.sun.org.apache.xpath.internal.XPath.<init>(Unknown Source)
at com.sun.org.apache.xpath.internal.XPath.<init>(Unknown Source)
... 30 more
com.sun.org.apache.xpath.internal.domapi.XPathStylesheetDOM3Exception: Prefix must resolve to a namespace: yweather
at com.sun.org.apache.xpath.internal.compiler.XPathParser.errorForDOM3(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.Lexer.mapNSTokens(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.Lexer.tokenize(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.Lexer.tokenize(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.initXPath(Unknown Source)
at com.sun.org.apache.xpath.internal.XPath.<init>(Unknown Source)
at com.sun.org.apache.xpath.internal.XPath.<init>(Unknown Source)
at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.compile(Unknown Source)
at com.nc.inotify.dp.xml.impl.XmlSource.getValue(XmlSource.java:180)
at com.nc.inotify.dp.xml.impl.XmlSource.update(XmlSource.java:284)
at com.nc.inotify.dp.xml.impl.XmlSourceFactory.getSource(XmlSourceFactory.java:155)
at com.nc.inotify.dp.xml.junit.TXmlSourceFactory.tesGetSource(TXmlSourceFactory.java:139)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
--------------- linked to ------------------
javax.xml.xpath.XPathExpressionException
at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.compile(Unknown Source)
at com.nc.inotify.dp.xml.impl.XmlSource.getValue(XmlSource.java:180)
at com.nc.inotify.dp.xml.impl.XmlSource.update(XmlSource.java:284)
at com.nc.inotify.dp.xml.impl.XmlSourceFactory.getSource(XmlSourceFactory.java:155)
at com.nc.inotify.dp.xml.junit.TXmlSourceFactory.tesGetSource(TXmlSourceFactory.java:139)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at
//rss/channel/item/yweather:forecast/text()
//rss/channel/item/guid/text()
DONE
解决方法:
我能够通过使用不支持名称空间的DocumentBuilderFactory来重现您的错误.
假设您的convert方法看起来像这样：
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(inputSource);
然后你可以试试这个：
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
dbFactory.setNamespaceAware(true);
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(inputSource);
这可以解释为什么NamespaceResolver无法获取namespaceURI.
标签：java,xml,xpath,document,xml-namespaces 来源： https://codeday.me/bug/20190718/1493010.html