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javaxmlclassdocumentjdom

adding content to existing xml with jdom


package xml.dierenshop.flaming.v1;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.output.XMLOutputter;
import org.jdom2.output.Format;
import java.io.FileWriter;
import java.io.IOException;

public class Writer {

    public void Writer(String categorie, String code, String naamartikel, String beschrijvingartikel, double prijz, String imgurl, String imgurl2, String imgurl3, String imgurl4, String imgurl5) {
        String prijs = String.valueOf(prijz);
        Document document = new Document();
        Element root = new Element("productlist");
        String naamelement = "naam";
        String categorieelement = "category";
        String descriptionelement = "description";
        Element child = new Element("product");
        child.addContent(new Element(categorieelement).setText(categorie));
        child.addContent(new Element("code").setText(code));
        child.addContent(new Element(naamelement).setText(naamartikel));
        child.addContent(new Element(descriptionelement).setText(beschrijvingartikel));
        child.addContent(new Element("price").setText(prijs));
        child.addContent(new Element("image").setText(imgurl));
        child.addContent(new Element("image").setText(imgurl2));
        child.addContent(new Element("image").setText(imgurl3));
        child.addContent(new Element("image").setText(imgurl4));
        child.addContent(new Element("image").setText(imgurl5));
        root.addContent(child);
        document.setContent(root);
        try {
            FileWriter writer = new FileWriter("products.xml");
            XMLOutputter outputter = new XMLOutputter();
            outputter.setFormat(Format.getPrettyFormat());
            outputter.output(document, writer);
            outputter.output(document, System.out);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

This is my class for writing an xml file with variables from my main class. The output here would be :

http://pastebin.com/nFtiv2b8

Now I have a problem, the next time I run this java application I want it to add a new product but keep the old one. However every time I try this, it replaces the old data with the new data.


Solution

  • Basically, you need to load an existing xml file and make a Document of it by parsing it and getting the root element from it. If the file does not exist then create a new document and a new root element. After that you can go on with the code you have shown.

    Create a class Product to hold product data. Passing product data each as argument to a method is a no-go.

    Product class (for simplicity all fields are public, this not a good practice, you should make them at least protected and for each a getter and a setter method)

    public class Product {
        public String categorie;
        public String code;
        public String naamartikel;
        public String beschrijvingartikel;
        public double prijz;
        public String imgurl;
        public String imgurl2;
        public String imgurl3; 
        public String imgurl4;
        public String imgurl5;
    }
    

    Writer method

    public static void Writer(Product product) throws JDOMException, IOException {
    
        Document document = null;
        Element root = null;
    
        File xmlFile = new File("products.xml");
        if(xmlFile.exists()) {
            // try to load document from xml file if it exist
            // create a file input stream
            FileInputStream fis = new FileInputStream(xmlFile);
            // create a sax builder to parse the document
            SAXBuilder sb = new SAXBuilder();
            // parse the xml content provided by the file input stream and create a Document object
            document = sb.build(fis);
            // get the root element of the document
            root = document.getRootElement();
            fis.close();
        } else {
            // if it does not exist create a new document and new root
            document = new Document();
            root = new Element("productlist");
        }
    
    
        String prijs = String.valueOf(product.prijz);
        String naamelement = "naam";
        String categorieelement = "category";
        String descriptionelement = "description";
        Element child = new Element("product");
        child.addContent(new Element(categorieelement).setText(product.categorie));
        child.addContent(new Element("code").setText(product.code));
        child.addContent(new Element(naamelement).setText(product.naamartikel));
        child.addContent(new Element(descriptionelement).setText(product.beschrijvingartikel));
        child.addContent(new Element("price").setText(prijs));
        child.addContent(new Element("image").setText(product.imgurl));
        child.addContent(new Element("image").setText(product.imgurl2));
        child.addContent(new Element("image").setText(product.imgurl3));
        child.addContent(new Element("image").setText(product.imgurl4));
        child.addContent(new Element("image").setText(product.imgurl5));
        root.addContent(child);
        document.setContent(root);
        try {
            FileWriter writer = new FileWriter("products.xml");
            XMLOutputter outputter = new XMLOutputter();
            outputter.setFormat(Format.getPrettyFormat());
            outputter.output(document, writer);
            outputter.output(document, System.out);
            writer.close(); // close writer
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    

    and finally a little test

    public static void main(String[] args) throws JDOMException, IOException {
        Product product = null;
    
        product = new Product();
        product.categorie = "cat1";
        product.code = "code1";
        product.naamartikel = "naam1";
        product.beschrijvingartikel = "beschrijving1";
        product.prijz = 100d;
        product.imgurl = "http://localhost/img1.png";
        product.imgurl2 = "http://localhost/img2.png";
        product.imgurl3 = "http://localhost/img3.png";
        product.imgurl4 = "http://localhost/img5.png";
        product.imgurl5 = "http://localhost/img5.png";
        Writer(product);
    
        product = new Product();
        product.categorie = "cat2";
        product.code = "code2";
        product.naamartikel = "naam2";
        product.beschrijvingartikel = "beschrijving2";
        product.prijz = 200d;
        product.imgurl = "http://localhost/img21.png";
        product.imgurl2 = "http://localhost/img22.png";
        product.imgurl3 = "http://localhost/img23.png";
        product.imgurl4 = "http://localhost/img25.png";
        product.imgurl5 = "http://localhost/img25.png";
        Writer(product);
    
        product = new Product();
        product.categorie = "cat3";
        product.code = "code3";
        product.naamartikel = "naam3";
        product.beschrijvingartikel = "beschrijving3";
        product.prijz = 300d;
        product.imgurl = "http://localhost/img31.png";
        product.imgurl2 = "http://localhost/img32.png";
        product.imgurl3 = "http://localhost/img33.png";
        product.imgurl4 = "http://localhost/img35.png";
        product.imgurl5 = "http://localhost/img35.png";
        Writer(product);
    }
    

    Also, file name products.xml should not be hard coded in java file; instead pass it as an argument when you run the program.