import java.io.*;
import java.util.*;

import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamSource;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.XPath;
import org.dom4j.io.DOMWriter;
import org.dom4j.io.DocumentResult;
import org.dom4j.io.DocumentSource;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class TransformDOM4J {

    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) {
        Document doc;

        long start;
        long end;
        XPath xpath;
        int kk=10;
        Number number = new Integer(0);
        List nodeList = null;

        try {
            byte[] content = getBytesFromFile(new File("blog.xml"));
            ByteArrayInputStream bais = new ByteArrayInputStream(content);
            ByteArrayOutputStream baos = new ByteArrayOutputStream(content.length * 2);
            XMLWriter writer = new XMLWriter(baos);
            SAXReader reader = new SAXReader();
            doc = reader.read(bais);
            bais.reset();
            XPath xpath1 = doc.createXPath("count(//*)");
            XPath xpath2 = doc.createXPath("//item");
            XPath xpath3 = doc.createXPath("/blog/item");
            XPath xpath4 = doc.createXPath("//text()");
            XPath xpath5 = doc.createXPath("count(//item)");
            XPath xpath6 = doc.createXPath("count(/blog/item)");
            XPath xpath7 = doc.createXPath("/blog/item/body/p/a");

            start = System.currentTimeMillis();

            for (int ii = 0; ii < kk; ii++) {
                //parse
                doc = reader.read(bais);

                number  = xpath1.numberValueOf(doc);
                nodeList = xpath2.selectNodes(doc);
                nodeList = xpath3.selectNodes(doc);
                nodeList = xpath4.selectNodes(doc);
                number  = xpath5.numberValueOf(doc);
                number  = xpath6.numberValueOf(doc);

                Node node = doc.selectSingleNode("/blog/item[@num='a781']");
                node.detach();

                nodeList = xpath7.selectNodes(doc);
                Iterator it = nodeList.iterator();
                while (it.hasNext()) {
                    node = (Node) it.next();
                    node.detach();
                }


                bais.reset();
                writer.write(doc);
                baos.reset();

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


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

}