Kode Java - Learn Java by Examples

How do I change the XML root element name in JAXB?

By Wayan in XML Last modified: June 5, 2023 0 Comment

In the following code snippet you will learn how to change the default root element name of the XML generated by the JAXB API. By default, the name of the class is use as the root element name. To change the root element name we can use the name property of the @XmlRootElement annotation. In the Customer model below we change the root element name into cust.

package org.kodejava.xml;

import org.kodejava.xml.support.Address;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement(name = "cust")
@XmlType(propOrder = {"id", "name", "address"})
public class Customer {
    private Integer id;
    private String name;
    private Address address;

    @XmlElement
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @XmlElement
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @XmlElement
    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

package org.kodejava.xml.support;

public class Address {
    private String street;
    private String city;
    private String province;
    private String zipcode;
    private String country;

    // Getters & Setters
}

package org.kodejava.xml;

import org.kodejava.xml.support.Address;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBCustomRootElement {
    public static void main(String[] args) {
        Customer customer = new Customer();
        customer.setId(1);
        customer.setName("Johnny Mnemonic");

        Address address = new Address();
        address.setStreet("Sunset Road");
        address.setCity("Denpasar");
        address.setProvince("Bali");
        address.setZipcode("80225");
        address.setCountry("Indonesia");
        customer.setAddress(address);

        try {
            JAXBContext context = JAXBContext.newInstance(Customer.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
            marshaller.marshal(customer, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

When we convert this POJO to XML using JAXB API we will get the following result:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<cust>
    <id>1</id>
    <name>Johnny Mnemonic</name>
    <address>
        <city>Denpasar</city>
        <country>Indonesia</country>
        <province>Bali</province>
        <street>Sunset Road</street>
        <zipcode>80225</zipcode>
    </address>
</cust>

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.1</version>
    </dependency>    
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-ri</artifactId>
        <version>2.3.5</version>
        <type>pom</type>
    </dependency>
</dependencies>

How to convert object to XML using JAXB?

By Wayan in XML Last modified: June 5, 2023 1 Comment

JAXB, Java Architecture for XML Binding, it uses JAXB annotations to convert POJO to or from XML file. In this example you will learn how to convert an object / POJO into an XML document using JAXB. The process of converting an object into XML also known as marshalling. In this snippet our POJO is a class called Track as you can see below.

The first thing that we need to do is to annotate the Track POJO with a couple of JAXB annotations. For this example we add the @XmlRootElement, @XmlElement and @XmlAttribute annotations.

package org.kodejava.xml.support;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Track {
    private Integer id;
    private String title;

    public Track() {
    }

    public Integer getId() {
        return id;
    }

    @XmlAttribute
    public void setId(Integer id) {
        this.id = id;
    }

    @XmlElement
    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    @Override
    public String toString() {
        return "Track{" +
                "id=" + id +
                ", title='" + title + '\'' +
                '}';
    }
}

After we have the Track class annotated we can use the code snippet below to convert the POJO into XML. The step to take is to start by creating an instance of JAXBContext. From this context object we create the Marshaller object. To convert it to XML we called the marshall() method. The method have many overloads, in this case we just want to print the XML to the System.out.

package org.kodejava.xml;

import org.kodejava.xml.support.Track;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBObjectToXml {
    public static void main(String[] args) {
        Track track = new Track();
        track.setId(1);
        track.setTitle("Hey Jude");

        try {
            JAXBContext context = JAXBContext.newInstance(Track.class);

            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            marshaller.marshal(track, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

If you run this code you will get the following output:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<track id="1">
    <title>Hey Jude</title>
</track>

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-ri</artifactId>
        <version>2.3.5</version>
        <type>pom</type>
    </dependency>
</dependencies>

How to create an XML file of a POJO using JAXB?

By Wayan in XML Last modified: June 5, 2023 0 Comment

The code snippet below show you how to convert POJO into XML file using JAXB. To do this we can pass the output file where we want the XML to be saved to the marshaller object.

package org.kodejava.xml;

import org.kodejava.xml.support.Track;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import java.io.File;

public class JAXBObjectToXmlFile {
    public static void main(String[] args) {
        Track track = new Track();
        track.setId(2);
        track.setTitle("She Loves You");

        try {
            JAXBContext context = JAXBContext.newInstance(Track.class);

            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            File output = new File("Track.xml");
            marshaller.marshal(track, output);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

This snippet will create a file called Track.xml with the following content:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<track id="2">
    <title>She Loves You</title>
</track>

package org.kodejava.xml.support;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Track {
    private Integer id;
    private String title;

    public Track() {
    }

    public Integer getId() {
        return id;
    }

    @XmlAttribute
    public void setId(Integer id) {
        this.id = id;
    }

    @XmlElement
    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    @Override
    public String toString() {
        return "Track{" +
                "id=" + id +
                ", title='" + title + '\'' +
                '}';
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-ri</artifactId>
        <version>2.3.5</version>
        <type>pom</type>
    </dependency>
</dependencies>

How to convert an XML file into object using JAXB?

By Wayan in XML Last modified: June 5, 2023 0 Comment

In this code snippet you can learn how to convert or unmarshall an XML file into it corresponding POJO. The steps on unmarshalling XML to object begin by creating an instance of JAXBContext. With the context object we can then create an instance of Unmarshaller class. Using the unmarshall() method and pass an XML file will give us the target POJO as the result.

Let’s see the code snippet below:

package org.kodejava.xml;

import org.kodejava.xml.support.Track;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import java.io.File;
import java.net.URL;
import java.util.Objects;

public class JAXBXmlToObject {
    public static void main(String[] args) {
        try {
            URL resource = JAXBXmlToObject.class.getResource("/Track.xml");
            File file = new File(Objects.requireNonNull(resource).toURI());
            JAXBContext context = JAXBContext.newInstance(Track.class);

            Unmarshaller unmarshaller = context.createUnmarshaller();
            Track track = (Track) unmarshaller.unmarshal(file);

            System.out.println("Track = " + track);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Here is the context of Track.xml:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<track id="2">
    <title>She Loves You</title>
</track>

package org.kodejava.xml.support;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Track {
    private Integer id;
    private String title;

    public Track() {
    }

    public Integer getId() {
        return id;
    }

    @XmlAttribute
    public void setId(Integer id) {
        this.id = id;
    }

    @XmlElement
    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    @Override
    public String toString() {
        return "Track{" +
                "id=" + id +
                ", title='" + title + '\'' +
                '}';
    }
}

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-ri</artifactId>
        <version>2.3.5</version>
        <type>pom</type>
    </dependency>
</dependencies>

How do I build object from XML file using SAX?

By Wayan in XML Last modified: June 2, 2023 0 Comment

This example will show you how to parse an XML file using SAX parser and build an object graph from the parsed XML. We will read the records.xml file that contains some recording information and create the Record object from it.

The DefaultHandler in this example created as an anonymous class. We override some method related to the ContentHandler interface such as the startElement, endElement and characters methods.

package org.kodejava.xml;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import org.kodejava.xml.support.Record;

public class SAXDataDemo {
    // List of our records.
    private final List<Record> records = new ArrayList<>();

    // Stacks for storing the elements and objects.
    private final Stack<String> elements = new Stack<>();
    private final Stack<Record> objects = new Stack<>();

    public static void main(String[] args) {
        SAXDataDemo demo = new SAXDataDemo();
        demo.run();
    }

    private void run() {
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser parser = factory.newSAXParser();

            String filename = "/records.xml";
            InputStream is = getClass().getResourceAsStream(filename);

            parser.parse(is, new DefaultHandler() {
                @Override
                public void startElement(String uri, String localName, String qName,
                                         Attributes attributes) throws SAXException {
                    elements.push(qName);
                    if ("record".equals(qName)) {
                        Record record = new Record();
                        objects.push(record);
                        records.add(record);
                    }
                }

                @Override
                public void endElement(String uri, String localName,
                                       String qName) throws SAXException {
                    elements.pop();
                }

                @Override
                public void characters(char[] ch, int start, int length)
                        throws SAXException {

                    String value = new String(ch, start, length);
                    if (value.length() == 0) {
                        return;
                    }

                    if ("title".equals(currentElement())) {
                        Record record = objects.peek();
                        record.setTitle(value);
                    } else if ("artist".equals(currentElement())) {
                        Record record = objects.peek();
                        record.setArtist(value);
                    } else if ("genre".equals(currentElement())) {
                        Record record = objects.peek();
                        record.setGenre(value);
                    } else if ("year".equals(currentElement())) {
                        Record record = objects.peek();
                        record.setYear(Integer.parseInt(value));
                    }
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }

        for (Record record : records) {
            System.out.println("record = " + record);
        }
    }

    private String currentElement() {
        return elements.peek();
    }
}

The Record class.

package org.kodejava.xml.support;

public class Record {
    private String title;
    private String artist;
    private String genre;
    private int year;

    public Record() {
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public void setArtist(String artist) {
        this.artist = artist;
    }

    public void setGenre(String genre) {
        this.genre = genre;
    }

    public void setYear(int year) {
        this.year = year;
    }

    @Override
    public String toString() {
        return "Record{" +
                "title='" + title + "'\n" +
                ", artist='" + artist + "'\n" +
                ", genre='" + genre + "'\n" +
                ", year=" + year +
                '}';
    }
}

The following XML is the content of our records.xml file.

<?xml version="1.0"?>
<root>
    <records>
        <record>
            <title>Brand New Eyes</title>
            <artist>Paramore</artist>
            <genre>Punk Rock</genre>
            <year>2011</year>
        </record>
        <record>
            <title>Rock Beatles</title>
            <artist>Various Artist</artist>
            <genre>Rock</genre>
            <year>2010</year>
        </record>
    </records>
</root>

When we run this example will get the following output:

record = Record{title='Brand New Eyes'
, artist='Paramore'
, genre='Punk Rock'
, year=2011}
record = Record{title='Rock Beatles'
, artist='Various Artist'
, genre='Rock'
, year=2010}