Java Integration

1. To start with we will create a project named DOMReader

2. We will start with two simple java class files. readXMLDOM and DOMReader. We will update the code step by step. 

 

package com.javatweaks.dom;

import java.util.ArrayList;

import java.util.List;

import com.javatweaks.sax.read.Items;

public class DOMReader {

public List<Items> getDataFromXML(String filename) {

List<Items> data = new ArrayList<>();

return data;

}

}

 

 

package com.javatweaks.dom;

import java.io.IOException;

import java.util.List;

import javax.xml.parsers.ParserConfigurationException;

import com.javatweaks.sax.read.Items;

import com.javatweaks.sax.read.SAXItemsHandler;

public class readXMLDOM {

public static void main(String[] args) throws IOException, ParserConfigurationException {

    DOMReader reader = new DOMReader();

    String filename = "C:\\Users\\xxxx\\Documents\\Java_XML\\items.xml";

    List<Items> data  = reader.getDataFromXML(filename);

    System.out.println("There are " + data.size() + " records");

}

}

 

3. Reading the XML file is similar to what we did to write XML. 

• Create a DocumentBuilderFactory object. 

• Create a DocumentBuilder using the factory instance. 

• Parse the xml document using builder instance. 

 

 

File inputFile = new File(filename);

Document doc = null;

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

doc = builder.parse(inputFile);

 

4. Place the code inside the try catch block, because later we will handle exceptions while reading the XML File. 

 

5. The simplest way to retrieve data is using a NodeList and then getting each element using the below code. 

 

NodeList list = doc.getElementsByTagName("item");

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

    Items item = new Items();

    data.add(item);

    Element itemElement = (Element) list.item(i);

    String idString = itemElement.getAttribute(Items.ID);

    item.setId(Integer.parseInt(idString));

    String content = getTextFromElement(itemElement, Items.MAN);

    item.setManufacturer(content);

    content = getTextFromElement(itemElement, Items.NAME);

    item.setName(content);

    content = getTextFromElement(itemElement, Items.PRICE);

    item.setPrice(content);

}

 

public String getTextFromElement(Element itemElement, String elementName) {

    Element node = (Element) itemElement.getElementsByTagName(elementName).item(0);

    String content = node.getTextContent();

return content;

}

 

 

Below is the code. 

 

DOMReader.java 

 

package com.javatweaks.dom;

import java.io.File;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.NodeList;

import org.xml.sax.SAXException;

 

public class DOMReader {

    public List<Items> getDataFromXML(String filename)  {

        List<Items> data = new ArrayList<>();

        File inputFile = new File(filename);

        Document doc = null;

        try {

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

            DocumentBuilder builder = factory.newDocumentBuilder();

            doc = builder.parse(inputFile);

        } catch (ParserConfigurationException  | SAXException | IOException e) {

            e.printStackTrace();

        }

        

        NodeList list = doc.getElementsByTagName("item");

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

            Items item = new Items();

            data.add(item);

            Element itemElement = (Element) list.item(i);

            String idString = itemElement.getAttribute(Items.ID);

            item.setId(Integer.parseInt(idString));

            String content = getTextFromElement(itemElement, Items.MAN);

            item.setManufacturer(content);

            content = getTextFromElement(itemElement, Items.NAME);

            item.setName(content);

            content = getTextFromElement(itemElement, Items.PRICE);

            item.setPrice(content);

        }

        

        return data;

    }

 

    public String getTextFromElement(Element itemElement, String elementName) {

        Element node = (Element) itemElement.getElementsByTagName(elementName).item(0);

        String content = node.getTextContent();

        return content;

    }

 

}

 

 

readXMLDOM.java

package com.javatweaks.dom;

 

import java.io.IOException;

import java.util.List;

import javax.xml.parsers.ParserConfigurationException;

import com.javatweaks.sax.read.Items;

 

public class readXMLDOM {

 

    public static void main(String[] args) throws IOException, ParserConfigurationException {

        DOMReader reader = new DOMReader();

        String filename = "C:\\Users\\xxxx\\Documents\\Java_XML\\items.xml";

        List<Items> data  = reader.getDataFromXML(filename);

        

        for (Items items : data) {

            System.out.println(items.getManufacturer()+" "+ items.getId() +  " "+ items.getName() +" " + items.getPrice());

        }

        

    }

 

}

 

6. If we run the program, the output will be like below. 

 

Apple Inc 1 iPhone 5 600

Apple Inc 2 iPhone 6 700

Motorola 3 Moto X 200

Motorola 4 Moto G 450

Samsung Corp 5 Samsung S4 550