Re: java get xml file line number for the current node

On 2/20/2012 9:32 AM, Arne Vajh?j wrote:


If we assume:
- you use W3C DOM
- you only need line number for element nodes
- you really need it
- you are willing to write some ugly hacks
then try something like:

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;
import java.util.Queue;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSOutput;
import org.w3c.dom.ls.LSSerializer;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class ParseWithLineNumbers {
    public static Document parseNormal(String fnm) throws
ParserConfigurationException, SAXException, IOException {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder db = dbf.newDocumentBuilder();
        return db.parse(new File(fnm));
    }
    public static Document parseSpecial(String fnm) throws
ParserConfigurationException, SAXException, IOException {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder db = dbf.newDocumentBuilder();
        return db.parse(new InputSource(new SpecialReader(fnm)));
    }
    public static void print(Document doc) throws ClassCastException,
ClassNotFoundException, InstantiationException, IllegalAccessException {
        DOMImplementation impl =
DOMImplementationRegistry.newInstance().getDOMImplementation("XML 3.0");
        DOMImplementationLS feature =
(DOMImplementationLS)impl.getFeature("LS","3.0");
         LSSerializer ser = feature.createLSSerializer();
         LSOutput output = feature.createLSOutput();
         output.setByteStream(System.out);
         ser.write(doc, output);
    }
    public static void main(String[] args) throws Exception {
        Document d1 = parseNormal("test.xml");
        print(d1);
        Document d2 = parseSpecial("test.xml");
        print(d2);
    }
}

class SpecialReader extends FileReader {
    private int lineno;
    private boolean inelm;
    private boolean eof;
    private Queue<Character> extra;
    public SpecialReader(String fnm) throws FileNotFoundException {
        super(fnm);
        lineno = 1;
        inelm = false;
        eof = false;
        extra = new LinkedList<Character>();
    }
    @Override
    public int read(char[] ch, int ix, int n) throws IOException {
        if(eof) return -1;
        int res = 0;
    wloop:
        while(res < n) {
            int c = extra.isEmpty() ? super.read() : extra.remove();
            if(inelm && (c == ' ' || c == '>')) {
         for(char xc : (" lineno='" + lineno +"'").toCharArray()) {
         extra.add(xc);
         }
         extra.add((char)c);
         c = extra.remove();
         inelm = false;
            }
            switch(c) {
                case '\n' :
                 lineno++;
                 break;
                case '<' :
                 inelm = true;
                    break;
                case '/':
                 inelm = false;
                 break;
                case -1 :
                 eof = true;
                 break wloop;
                default:
                 /* nothing */
                 break;
            }
            ch[ix + res] = (char)c;
            res++;
        }
        return res;
    }
}

It adds an attribute lineno to all elment nodes.

Arne