如何使用按位-和xpath和Java在xml中查找？

Question

I have this sample xml .

Each row has an id field, it has values as bits.

And I want to find in this file with bitwise-and operator but I don't know if this is possible.

I read about the operator '&' in javascript or comand BITAND in Oracle but nothing in xml o xpath.

This is the example code in java and xpath:

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;

import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class Util implements java.io.Serializable  {

    static public String filter_xpath_bitand (int var_tipo)

        NodeList nodeList = null;
        Element  element  = null;
        try {
            XPath xpath = XPathFactory.newInstance().newXPath();
            DocumentBuilderFactory factory  = DocumentBuilderFactory.newInstance();
            DocumentBuilder        builder  = factory.newDocumentBuilder();
            Document            document = builder.parse(new File(fileXML));      
           nodeList = (NodeList)xpath.evaluate("/test/row[(id & \""+ var_tipo +"\") > 1]", document.getDocumentElement(), XPathConstants.NODESET);
        } catch (Exception e) {
            System.out.println("*** filterXML --> exception: " + e.toString());
        }

    }

}

Answer 1

From looking at the XPATH reference there is no such thing as bitwise operations.

You could work around that though by making use of existing operations (mod etc).

See here for a related question.

EDIT:

Sample xml:

<?xml version="1.0" encoding="UTF-8"?>
<test>
    <row>
        <id>32</id>
        <titulo>yellow</titulo>
    </row>
    <row>
        <id>16</id>
        <titulo>green</titulo>
    </row>
    <row>
        <id>8</id>
        <titulo>red</titulo>
    </row>
    <row>
        <id>1</id>
        <titulo>blue</titulo>
    </row>
    <row>
        <id>2</id>
        <titulo>white</titulo>
    </row>
    <row>
        <id>4</id>
        <titulo>black</titulo>
    </row>
</test>

Java code:

import java.io.File;
import java.util.HashSet;
import java.util.Set;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;

import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class BitWiseXPathTest {

    public static void main(String[] args) {

        Set<String> selectedColors = new HashSet<String>();
        int var_tipo = 33;
        try {
            XPath xpath = XPathFactory.newInstance().newXPath();
            DocumentBuilderFactory factory = DocumentBuilderFactory
                    .newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            String fileXML = "bitwise.xml";
            Document document = builder.parse(new File(fileXML));

            String evalStr = "/test/row/id";
            NodeList nodeList = (NodeList)xpath.evaluate(evalStr, document.getDocumentElement(), XPathConstants.NODESET);

            for (int i = 0; i < nodeList.getLength(); i++) {
                Node aNode = nodeList.item(i);
                if( (Integer.parseInt(aNode.getTextContent()) & var_tipo) > 0) {
                    //System.out.println("color: "+aNode.getNextSibling().getNextSibling().getTextContent());
                    selectedColors.add(aNode.getNextSibling().getNextSibling().getTextContent());
                }
            }

        } catch (Exception e) {
            System.out.println("*** filterXML --> exception: " + e.toString());
        }

        System.out.println(selectedColors);

    }

}

Again, XPATH doesn't seem to have a bitwise operation. You could move the operation outside of XPATH and do it in Java as a workaround.