Updating Pentaho PRPT files to add a PreProcessor

In my previous post (see here) I mentioned that I couldn’t add a pre-processor to a Pentaho report using the report designer. So, I’ve written a short Java program that does just that.
Note that I use a neat open source library called Zip4J (you can get it here).

package com.tona.rprt;

import java.io.File;
import java.io.FileWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;

import net.lingala.zip4j.core.ZipFile;
import net.lingala.zip4j.model.ZipParameters;

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

public class Main {
	private static final String CONFIG_FILE_NAME = "layout.xml";
	public static void main(String[] args) throws Exception {
		ZipFile reportFile = new ZipFile("");

		File tempDirectory = createTempDirectory();
		String path = tempDirectory.getAbsolutePath();
		reportFile.extractFile(CONFIG_FILE_NAME, path);

		System.out.println("Extraced file to " + path);
		File updatedFile = new File(path + File.separator + CONFIG_FILE_NAME);

		// Update the file
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		DocumentBuilder db = dbf.newDocumentBuilder();
		Document doc = db.parse(updatedFile);
		System.out.println("Parsed document");
		Element layoutNode = doc.getDocumentElement();
		Element preProcessorElement = doc.createElement("preprocessor");
		preProcessorElement.setAttribute("class", "com.tona.report.infra.TonaWizardProcessor");
		Node firstLayoutChild = layoutNode.getFirstChild(); 
		layoutNode.insertBefore(preProcessorElement, firstLayoutChild);
		System.out.println("Added child");

		FileWriter output = new FileWriter(updatedFile);
		javax.xml.transform.stream.StreamResult result = new javax.xml.transform.stream.StreamResult(output);

		TransformerFactory tf = TransformerFactory.newInstance();
		Transformer t = tf.newTransformer();
		t.transform(new DOMSource(doc), result);
		System.out.println("Updated XML file");
		ZipParameters parameters = new ZipParameters();
		reportFile.addFile(updatedFile, parameters);
		System.out.println("Update ZIP file");
		System.out.println("Removed temporary directory");
	private static File createTempDirectory() throws Exception
		    File temp = File.createTempFile("temp", Long.toString(System.nanoTime()));

		    if(!(temp.delete())) {
		        throw new Exception("Could not delete temp file: " + temp.getAbsolutePath());

		    if(!(temp.mkdir())) {
		        throw new Exception("Could not create temp directory: " + temp.getAbsolutePath());

		    return temp;