By default when marshaling to xml file, all properties are marshaled as elements. This default behaviour can be changed and this post explains how to do it.

In this post I will marshall the below java bean class, and id property as its attribute.

Country

1  package package1;
2  
3  import javax.xml.bind.annotation.XmlAttribute;
4  import javax.xml.bind.annotation.XmlRootElement;
5  
6  @XmlRootElement
7  public class Country {
8   private int id;
9      private String name;
10     private int population;
11 
12     @XmlAttribute
13     public int getId() {
14      return id;
15  }
16  public void setId(int id) {
17      this.id = id;
18  }
19  public String getName() {
20         return name;
21     }
22     public void setName(String name) {
23         this.name = name;
24     }
25     public int getPopulation() {
26         return population;
27     }
28     public void setPopulation(int population) {
29         this.population = population;
30     }
31 
32     @Override
33     public String toString() {
34         StringBuilder sb = new StringBuilder();
35         sb.append("{");
36         sb.append("name:").append(this.name).append(",");
37         sb.append("population:").append(this.population).append("}");
38 
39         return sb.toString();
40     }
41 }

Since I want the id property as an attribute, I mark the getter method with XmlAttribute annotation. Any getter annotated with this annotation will be stored as element’s attribute.

Main Code

package package1;

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

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

public class XMLAttributeDemo {
    public static void main(String[] args) throws JAXBException, IOException {
        JAXBContext jaxbContext = JAXBContext.newInstance(Country.class);

        Marshaller marshaller = jaxbContext.createMarshaller();
        Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();

        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        Country country = new Country();
        country.setId(1);
        country.setName("India");
        country.setPopulation(10000000);

        File file = new File("result.xml");
        FileWriter fw = new FileWriter(file);

        marshaller.marshal(country, fw);
    }
}

Output

<?xml version=”1.0″ encoding=”UTF-8″ standalone=”yes”?>
<country id=”1″>
<name>India</name>
<population>10000000</population>
</country>

Explanation

From the output we can see that id property is marshalled as attribute of country element instead of an element itself.