Marshaller and Unmarshaller (JAXB - Java Architechture for XML Binding)

 Marshaller allows us to write an object to a xml file. 

https://www.youtube.com/watch?v=ZtQ5-c4nAKY

package main;

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

@XmlRootElement
public class Employee {

    private String name;
    private int number;
    private int age;
    private String mail;
    private String city;

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

    @XmlElement
    public void setNumber(int number) {
        this.number = number;
    }

    @XmlElement
    public void setAge(int age) {
        this.age = age;
    }

    @XmlElement
    public void setMail(String mail) {
        this.mail = mail;
    }

    @XmlElement
    public void setCity(String city) {
        this.city = city;
    }

    public String getName() {
        return name;
    }

    public int getNumber() {
        return number;
    }

    public int getAge() {
        return age;
    }

    public String getMail() {
        return mail;
    }

    public String getCity() {
        return city;
    }
}

package main;

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

public class JaxbWriter {
    public static void main(String[] args) {
        Employee employee = new Employee();
        employee.setAge(29);
        employee.setName("Parvin");
        employee.setCity("Baku");
        employee.setMail("etibarliparvin@gmail.com");
        employee.setNumber(8204296);

        File file = new File("C:\\Users\\LENOVO\\Desktop\\test1.xml");
        try {
            JAXBContext context = JAXBContext.newInstance(Employee.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            marshaller.marshal(employee, file);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
This program creates xml file in the shown directory.
<?xml version="1.0" encoding="UTF-8" standalone="true"?>

-<employee>

<age>29</age>

<city>Baku</city>

<mail>etibarliparvin@gmail.com</mail>

<name>Parvin</name>

<number>8204296</number>

</employee>


Unmarshaller reads from xml file and transfers elements to a java object.
package main;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import java.io.File;

public class JaxbReader {
    public static void main(String[] args) {
        Employee employee = null;
        File file = new File("C:\\Users\\LENOVO\\Desktop\\test1.xml");
        try {
            JAXBContext context = JAXBContext.newInstance(Employee.class);
            Unmarshaller unmarshaller = context.createUnmarshaller();
            employee = (Employee) unmarshaller.unmarshal(file);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(employee.getName());
    }
}
Another example:
package externals;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import java.io.File;

@XmlRootElement(name = "DbConfig")
@XmlAccessorType(XmlAccessType.FIELD)
public class DbConfig {

    @XmlElement(name = "url")
    private String url;
    @XmlElement(name = "username")
    private String username;
    @XmlElement(name = "password")
    private String password;

    public String getUrl() {
        return url;
    }

    public DbConfig setUrl(String url) {
        this.url = url;
        return this;
    }

    public String getUsername() {
        return username;
    }

    public DbConfig setUsername(String username) {
        this.username = username;
        return this;
    }

    public String getPassword() {
        return password;
    }

    public DbConfig setPassword(String password) {
        this.password = password;
        return this;
    }
    
}
package externals;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import java.io.File;
import java.sql.Connection;
import java.sql.DriverManager;

public class MyConnection2 {

    public Connection connect() throws Exception {
        try {
            JAXBContext context = JAXBContext.newInstance(DbConfig.class);
            Unmarshaller unmarshaller = context.createUnmarshaller();
            DbConfig dbConfig = (DbConfig) unmarshaller.unmarshal(new File("C:\\Users\\LENOVO\\Desktop\\dbconfig.xml"));
            return DriverManager.getConnection(dbConfig.getUrl(), dbConfig.getUsername(), dbConfig.getPassword());
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}