import org.w3c.dom.*;
import java.io.*;
import java.util.*;

import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import javax.xml.transform.stream.*;
import javax.xml.parsers.*;
import javax.xml.xpath.*;

public class TransformDOM {

    public static byte[] getBytesFromFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);
        long length = file.length();

        byte[] bytes = new byte[(int)length];

        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
               && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
            offset += numRead;
        }

        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "+file.getName());
        }

        is.close();
        return bytes;
    }

    public static void main(String args[]) {
        test(true);
        test(true);
        test(true);
        test(true);
        test(true);
        test(true);
        test(true);
        test(true);
        test(true);
        test(true);
    }

    public static void test(boolean forReal) {
        long start;
        long end;
        int kk=10;
        double time = 0.0;
        int i=0;
        int j = 0;
        Document doc = null;
        XPathExpression xpath;
        Number number = new Integer(0);
        Object res = null;
        NodeList set = null;

        try {
            byte[] content = getBytesFromFile(new File("blog.xml"));
            ByteArrayInputStream bais = new ByteArrayInputStream(content);
            ByteArrayOutputStream baos = new ByteArrayOutputStream(content.length * 2);
            DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

            start = System.currentTimeMillis();
            for (int ii=0; i < kk; i++) {
                doc = builder.parse(bais);
                bais.reset();
                xpath = XPathFactory.newInstance().newXPath().compile("count(//*)");
                res = xpath.evaluate(doc, XPathConstants.NUMBER);
                xpath = XPathFactory.newInstance().newXPath().compile("//*");
                res = xpath.evaluate(doc, XPathConstants.NODESET);
                xpath = XPathFactory.newInstance().newXPath().compile("/blog/item");
                res = xpath.evaluate(doc, XPathConstants.NODESET);
                xpath = XPathFactory.newInstance().newXPath().compile("//text()");
                res = xpath.evaluate(doc, XPathConstants.NODESET);
                xpath = XPathFactory.newInstance().newXPath().compile("count(//item)");
                res = xpath.evaluate(doc, XPathConstants.NUMBER);
                xpath = XPathFactory.newInstance().newXPath().compile("count(/blog/item)");
                res = xpath.evaluate(doc, XPathConstants.NUMBER);
                xpath = XPathFactory.newInstance().newXPath().compile("/blog/item[@num='a781']");
                set = (NodeList) xpath.evaluate(doc, XPathConstants.NODESET);
                for (int r=set.getLength(); r > 0;) {
                    Node node = set.item(--r);
                    node.getParentNode().removeChild(node);
                }
                xpath = XPathFactory.newInstance().newXPath().compile("/blog/item/body/p/a");
                set = (NodeList) xpath.evaluate(doc, XPathConstants.NODESET);
                for (int r=set.getLength(); r > 0;) {
                    Node node = set.item(--r);
                    node.getParentNode().removeChild(node);
                }
                Source source = new DOMSource(doc);
                Result result = new StreamResult(baos);
                Transformer xformer = TransformerFactory.newInstance().newTransformer();
                xformer.transform(source, result);
                baos.reset();
            }

            end = System.currentTimeMillis();
            System.err.println("average cycle time (ms): " + (end - start) / kk);


        } catch (Exception ie) {
            ie.printStackTrace();
        }
    }

}