从xml节点获取行号 - java [英] Get line number from xml node - java
问题描述
我已经解析了一个XML文件,并且得到了一个我感兴趣的节点。我现在如何在源XML文件中找到此节点出现的行号?
I have parsed an XML file and have gotten a Node that I am interested in. How can I now find the line number in the source XML file where this node occurs?
编辑:
目前我正在使用SAXParser来解析我的XML。但是我会对使用任何解析器的解决方案感到满意。
Currently I am using the SAXParser to parse my XML. However I will be happy with a solution using any parser.
除了Node之外,我还有节点的XPath表达式。
Along with the Node, I also have the XPath expression for the node.
我需要获取行号,因为我在文本框中显示XML文件,需要突出显示节点出现的行。假设XML文件的格式很好,并且有足够的换行符。
I need to get the line number because I am displaying the XML file in a textbox, and need to highlight the line where the node occured. Assume that the XML file is nicely formatted with sufficient line breaks.
推荐答案
我按照这个例子运行了这个:
I have got this working by following this example:
http:/ /eyalsch.wordpress.com/2010/11/30/xml-dom-2/
此解决方案遵循Michael Kay建议的方法。以下是使用方法:
This solution follows the method suggested by Michael Kay. Here is how you use it:
// XmlTest.java
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
public class XmlTest {
public static void main(final String[] args) throws Exception {
String xmlString = "<foo>\n"
+ " <bar>\n"
+ " <moo>Hello World!</moo>\n"
+ " </bar>\n"
+ "</foo>";
InputStream is = new ByteArrayInputStream(xmlString.getBytes());
Document doc = PositionalXMLReader.readXML(is);
is.close();
Node node = doc.getElementsByTagName("moo").item(0);
System.out.println("Line number: " + node.getUserData("lineNumber"));
}
}
如果你运行这个程序,它会输出: 行号:3
If you run this program, it will out put: "Line number: 3"
PositionalXMLReader是上面链接的示例的略微修改版本。
PositionalXMLReader is a slightly modified version of the example linked above.
// PositionalXMLReader.java
import java.io.IOException;
import java.io.InputStream;
import java.util.Stack;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class PositionalXMLReader {
final static String LINE_NUMBER_KEY_NAME = "lineNumber";
public static Document readXML(final InputStream is) throws IOException, SAXException {
final Document doc;
SAXParser parser;
try {
final SAXParserFactory factory = SAXParserFactory.newInstance();
parser = factory.newSAXParser();
final DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
final DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
doc = docBuilder.newDocument();
} catch (final ParserConfigurationException e) {
throw new RuntimeException("Can't create SAX parser / DOM builder.", e);
}
final Stack<Element> elementStack = new Stack<Element>();
final StringBuilder textBuffer = new StringBuilder();
final DefaultHandler handler = new DefaultHandler() {
private Locator locator;
@Override
public void setDocumentLocator(final Locator locator) {
this.locator = locator; // Save the locator, so that it can be used later for line tracking when traversing nodes.
}
@Override
public void startElement(final String uri, final String localName, final String qName, final Attributes attributes)
throws SAXException {
addTextIfNeeded();
final Element el = doc.createElement(qName);
for (int i = 0; i < attributes.getLength(); i++) {
el.setAttribute(attributes.getQName(i), attributes.getValue(i));
}
el.setUserData(LINE_NUMBER_KEY_NAME, String.valueOf(this.locator.getLineNumber()), null);
elementStack.push(el);
}
@Override
public void endElement(final String uri, final String localName, final String qName) {
addTextIfNeeded();
final Element closedEl = elementStack.pop();
if (elementStack.isEmpty()) { // Is this the root element?
doc.appendChild(closedEl);
} else {
final Element parentEl = elementStack.peek();
parentEl.appendChild(closedEl);
}
}
@Override
public void characters(final char ch[], final int start, final int length) throws SAXException {
textBuffer.append(ch, start, length);
}
// Outputs text accumulated under the current node
private void addTextIfNeeded() {
if (textBuffer.length() > 0) {
final Element el = elementStack.peek();
final Node textNode = doc.createTextNode(textBuffer.toString());
el.appendChild(textNode);
textBuffer.delete(0, textBuffer.length());
}
}
};
parser.parse(is, handler);
return doc;
}
}
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