Question

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文件中找到此节点所在的行号？

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。

与Node一起，我也有节点的XPath表达式。

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。

Answer 1

我按照这个例子开展了这项工作：

http://eyalsch.wordpress.com/2010/11/30/xml-dom-2/

此解决方案遵循Michael Kay建议的方法。以下是您使用它的方式：

// 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"));
    }
}

如果您运行此程序，它将输出：“行号：3”

PositionalXMLReader是上面链接的示例的略微修改版本。

// 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;
    }
}

Answer 2

如果您使用的是SAX解析器，则可以使用Locator对象获取事件的行号，该对象通过setDocumentLocator（）回调通知ContentHandler。这在解析开始时调用，您需要保存定位器;然后在任何事件（例如startElement（））之后，可以调用getLineNumber（）等方法来获取源文件中的当前位置。（在startElement（）之后，定义回调以提供出现开始标记的“＆gt;”的行号。）

Answer 3

priomsrb's的答案很好，很有效。对于我的用例，我需要将其集成到现有的框架中，例如编码也包括在内。因此，以下重构被应用为具有单独的LineNumberHandler类。

然后，该代码还将与Sax InputSource一起使用，在其中可以像这样修改编码：

            // read in the xml document
            org.xml.sax.InputSource is=new org.xml.sax.InputSource();
            is.setByteStream(instream);
            if (encoding!=null) {
                is.setEncoding(encoding);
                if (Debug.CORE)
                    Debug.log("setting XML encoding to - "+is.getEncoding());
            }

单独的LineNumberHandler

/**
 * LineNumber Handler
 * @author wf
 *
 */
public static class LineNumberHandler extends DefaultHandler {

final Stack<Element> elementStack = new Stack<Element>();
final StringBuilder textBuffer = new StringBuilder();
private Locator locator;
private Document doc;

/**
 * create a line number Handler for the given document
 * @param doc
 */
public LineNumberHandler(Document doc) {
  this.doc=doc;
}

@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());
  }
}

};

PositionalXMLReader

public class PositionalXMLReader {
  final static String LINE_NUMBER_KEY_NAME = "lineNumber";
 /**
  * read a document from the given input strem
  * 
  * @param is
  *          - the input stream
  * @return - the Document
  * @throws IOException
  * @throws SAXException
  */
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);
    }
    LineNumberHandler handler = new LineNumberHandler(doc);
    parser.parse(is, handler);

    return doc;
  }
}

JUnit测试用例

package com.bitplan.common.impl;

import static org.junit.Assert.assertEquals;

import java.io.ByteArrayInputStream;
import java.io.InputStream;

import org.junit.Test;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

import com.bitplan.bobase.PositionalXMLReader;

public class TestXMLWithLineNumbers {

  /**
   * get an Example XML Stream
   * @return the example stream
   */
  public InputStream getExampleXMLStream() {
    String xmlString = "<foo>\n" + "    <bar>\n"
        + "        <moo>Hello World!</moo>\n" + "    </bar>\n" + "</foo>";

    InputStream is = new ByteArrayInputStream(xmlString.getBytes());
    return is;
  }

  @Test
  public void testXMLWithLineNumbers() throws Exception {
    InputStream is = this.getExampleXMLStream();
    Document doc = PositionalXMLReader.readXML(is);
    is.close();

    Node node = doc.getElementsByTagName("moo").item(0);
    assertEquals("3", node.getUserData("lineNumber"));
  }  
}

Answer 4

请注意，根据规范（ Locator.getLineNumber（）），该方法返回SAX事件结束的行号！

对于“startElement（）”，这意味着：

此处元素的行号 1 ：

<Element></Element>

此处元素的行号 3 ：

<Element
   attribute1="X"
   attribute2="Y">
</Element>

从xml节点获取行号 - java

4 个答案: