jaxb2-maven-plugin to generate java code from XSD schema

In this tutorial I will show how to generate the Java source code from XSD schema. I will use jaxb2-maven-plugin to generate the code using XSD file which will be declared in pom.xml to make it part of build, so when maven build is executed it will generate the java code using XSD. Class generation can be controlled in plugin configuration.

Maven changes (pom.xml)

Include below plugin in your pom.xml. Here we have done some configuration under configuration section as given below.
schemaDirectory: This is the directory where I keep my schema (XSD file).
outputDirectory: This is the java source location where I want to generate the Java files. If it is not given then by default it will be generate inside target folder.
clearOutputDir: If this property is true then it will generate the classes on each build otherwise it will generate only if output directory is empty.

<plugin>
 <groupId>org.codehaus.mojo</groupId>
 <artifactId>jaxb2-maven-plugin</artifactId>
 <version>1.6</version>
 <executions>
    <execution>
     <id>xjc</id>
     <goals>
        <goal>xjc</goal>
     </goals>
    </execution>
 </executions>
 <configuration>
    <schemaDirectory>${project.basedir}/src/main/resources/schema</schemaDirectory>
    <outputDirectory>${project.basedir}/src/main/java</outputDirectory>
    <clearOutputDir>false</clearOutputDir>
 </configuration>
</plugin>

XSD Schema (employee.xsd)

Below is the XSD schema which will be used to generate the Java class.

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://myexample.com/employee"
targetNamespace="http://myexample.com/employee">
 <xs:complexType name="employee">
  <xs:sequence>
   <xs:element name="name" type="xs:string"/>
   <xs:element name="age" type="xs:int"/>
   <xs:element name="organization" type="xs:string"/>
   <xs:element name="salary" type="xs:decimal"/>
  </xs:sequence>
 </xs:complexType>
</xs:schema>

XSD location is as given below in my application.

Generating Java classes

After setting up the above code and configuration, we can run the maven build by executing "men clean install". It will generate the Java classes using the XSD schema. Below is the generated code package structure after the build execution.

Below is the snap of code from generated classes. Getters/Setters are also generated but not included in example.

• Employee.java

@XmlAccessorType(XmlAccessType.FIELD)
 @XmlType(name = "employee", propOrder = {
     "name",
     "age",
     "organization",
     "salary"
 })

 public class Employee {
     @XmlElement(required = true)
     protected String name;

     protected int age;

     @XmlElement(required = true)
     protected String organization;

     @XmlElement(required = true)
     protected BigDecimal salary;

• ObjectFactory.java

@XmlRegistry
 public class ObjectFactory {
     /**
      * Create a new ObjectFactory that can be used to create new instances of schema derived classes for package: com.myexample.employee
      * 
      */
     public ObjectFactory() {

     } 

     /**
      * Create an instance of {@link Employee }
      * 
      */
     public Employee createEmployee() {
         return new Employee();
     } 
 }

• package-info.java

@javax.xml.bind.annotation.XmlSchema(namespace = "http://myexample.com/employee")
package com.myexample.employee;

That's all. Usually you may have a need to generate the class this way when you are creating some SOAP service client or you can use it to just create the Java POJO classes also.

You may be interested in my other post on generating Java classes using annotation processor.
https://www.thetechnojournals.com/2019/12/annotation-processor-to-generate-dto.html