Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class Main {
    private static XPath xpath = XPathFactory.newInstance().newXPath();
    private static Map<String, XPathExpression> cache = new HashMap<>();

    public static Element[] getElements(Element parent, String expression) {

        boolean isSimple = true;
        for (int i = 0; i < expression.length(); i++) {
            if (!Character.isAlphabetic(expression.charAt(i))) {
                isSimple = false;
                break;
            }
        }

        if (isSimple) {
            return getDirectElements(parent, expression);
        } else {
            try {
                XPathExpression xquery;
                if (cache.containsKey(expression)) {
                    xquery = cache.get(expression);
                } else {
                    xquery = xpath.compile(expression);
                    cache.put(expression, xquery);
                }

                return itemsOf((NodeList) xquery.evaluate(parent, XPathConstants.NODESET));
            } catch (XPathExpressionException ex) {
                return null;
            }
        }
    }

    public static Element[] getDirectElements(Element parent, String name) {

        NodeList children = parent.getChildNodes();
        List<Element> result = new LinkedList<>();

        for (int i = 0; i < children.getLength(); i++) {

            Node node = children.item(i);
            if (node.getNodeName().equals(name)) {
                result.add((Element) node);
            }
        }

        return result.toArray(new Element[0]);
    }

    public static Element[] itemsOf(final NodeList nodeList) {

        Element[] result = new Element[nodeList.getLength()];
        for (int i = 0; i < nodeList.getLength(); i++) {
            result[i] = (Element) nodeList.item(i);
        }

        return result;
    }
}