nileshkhaire / babycorn

Short and sweet strongly typed XML reader for JVM

BabyCorn XML

Short and sweet strongly typed XML reader for JVM.

BabyCorn XML is a library to read XML data into Java data types using XPath selector.

It could be a good configuration library because of in-built features like validator and preprocessor.

Adding BabyCorn XML to your build:

There are multiple options. Select one of the following:

Download from GitHub releases:

GitHub Releases

To add a dependency using Maven, use the following:

<dependency>
  <groupId>com.fervort.babycorn</groupId>
  <artifactId>babycorn-xml</artifactId>
  <version>1.0.0</version>
</dependency>

To add a dependency using Gradle:

implementation 'com.fervort.babycorn:babycorn-xml:1.0.0'

How to use :

In 3 quick steps:

1. Add BabyCorn XML jar to your build as specified in above options.
2. Create a Java class with fields and annotate it using XPath as per your XML file.
3. Create an object of a java field class you have created in the last step and pass it to BabyCornXML constructor. All values will be set to field class you have created. That's All!

Example :

Your XML :

<?xml version="1.0" encoding="UTF-8"?>
<students>
	<student>
		<name>Foo Bar</name>
		<rollno>11</rollno>
		<division>A</division>
		<lastYearGrade>78.77</lastYearGrade>
		<inTopTen>yes</inTopTen>
		<secretKeyNumber>922337203685477</secretKeyNumber>
		<studentWeight>63.9873333</studentWeight>
		<address postcode="900111" city="California"/>
		<hobbies>
			<hobby>Singing</hobby>
			<hobby>Reading</hobby>
			<hobby>Yoga</hobby>
		</hobbies>
		<subjects>
			<subject name="Science" teacherName="Abc Pqr"/>
			<subject name="Mathematics" teacherName="Lmn Opq"/>
			<subject name="English" teacherName="Def Xyz"/>
		</subjects>
		<projects>
			<project id="101">Painting</project>
			<project id="102">calligraphy</project>
		</projects>
	</student>
</students>	

Create a Java class with fields and annotate it using XPath :

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fervort.babycorn.xml.annotation.BabyCornXMLField;

public class Students {

	@BabyCornXMLField(xPath = "students/student/name")
	String name;

	@BabyCornXMLField(xPath = "students/student/rollno")
	int rollNumber;
	
	@BabyCornXMLField(xPath = "students/student/division")
	char division;
	
	@BabyCornXMLField(xPath = "students/student/lastYearGrade")
	float lastYearGradeofStudent;
	
	@BabyCornXMLField(xPath = "students/student/inTopTen")
	boolean isStudentInTop10;
	
	@BabyCornXMLField(xPath = "students/student/secretKeyNumber")
	long secretKeyNumber;
	
	@BabyCornXMLField(xPath = "students/student/studentWeight")
	double weight;
	
	@BabyCornXMLField(xPath = "students/student/hobbies/hobby" ,listValue = "text()")
	List hobbies = new ArrayList();
	
	@BabyCornXMLField(xPath = "students/student/subjects/subject" ,mapKey = "@name",mapValue = "@teacherName")
	Map<String,String> subjects = new HashMap();
}

Create an object of a java field class you have created in the last step and pass it to BabyCornXML constructor :

public class StudentTest {

	public static void main(String[] args) throws Exception {
		
		Students students = new Students();
		
		BabyCornXML babyCornXML = new BabyCornXML("Students.xml",students);
		
		System.out.println("Name: "+students.name);
		
		System.out.println("Roll Number "+students.rollNumber);
		
		System.out.println("Division "+students.division);
		
		System.out.println("In Top 10 "+students.isStudentInTop10);
		
		System.out.println("last year grade "+students.lastYearGradeofStudent);
		
		System.out.println("Weight "+students.weight);
	
		System.out.println("SecretKey "+students.secretKeyNumber);

		System.out.println("Hobbies "+students.hobbies);
		
		System.out.println("Subjects "+students.subjects);

	}

}

Output :

Name: Foo Bar
Roll Number 11
Division A
In Top 10 true
last year grade 78.77
Weight 63.9873333
SecretKey 922337203685477
Hobbies [Singing, Reading, Yoga]
Subjects {English=Def Xyz, Science=Abc Pqr, Mathematics=Lmn Opq}

Handling multiple nodes :

If there are multiple nodes/records in the XML, you can create 2 classes, 1 for holding list of records and other one for holding fields. For example:

XML with multiple nodes:

<teachers>
	<teacher>
		<name>Abc</name>
		<tid>101</tid>
		<department>Art</department>
	</teacher>
	<teacher>
		<name>Pqr</name>
		<tid>102</tid>
		<department>Science</department>
	</teacher>
	<teacher>
		<name>Xyz</name>
		<tid>103</tid>
		<department>Commerce</department>
	</teacher>
</teachers>

Class to hold list of teachers:

public class Teachers {

	// Note Xpath, it is teachers/teacher
	@BabyCornXMLField(xPath = "teachers/teacher")
	List<Teacher> teacherList = new ArrayList<Teacher>();
}

Class to hold teacher fields:

public class Teacher {

	// Note Xpath, it is only name, excluding teachers/teacher
	@BabyCornXMLField(xPath = "name")
	public String name;
	
	@BabyCornXMLField(xPath = "tid")
	public int tid;
	
	@BabyCornXMLField(xPath = "department")
	public String department;
}

Get list of teachers and fields:

public static void main(String[] args) throws Exception {

	Teachers teachers = new Teachers();
	BabyCornXML babyCornXML = new BabyCornXML("Teachers.xml",teachers);
	
	// Iterate through each teacher
	for(Teacher teacher: teachers.teacherList)
	{
		System.out.println("name: "+teacher.name);
		System.out.println("teacher id: "+teacher.tid);
		System.out.println("department: "+teacher.department);
		System.out.println("");
	}

Output :

name: Abc
teacher id: 101
department: Art

name: Pqr
teacher id: 102
department: Science

name: Xyz
teacher id: 103
department: Commerce

Validator & Pre processor :

Anything can be written in a XML file that can cause a program failure. To avoid such scenarios, validator can be used. You can write your own validator or use built in validators.

Writing custom validator:

You can write your own validators. Here are simple steps:

1. Add @BabyCornXMLValidation(validationMethod = "validateEmployeeName") annotation on the field. Here validateEmployeeName is a java method, where validation code will be written.

public class Employees {
	
	@BabyCornXMLValidation(validationMethod = "validateEmployeeName")
	@BabyCornXMLField(xPath = "employees/employee/name")
	public String name;

}

2. Write a validation method validateEmployeeName in class Emplyees. Method should have 2 parameters as written below.

public ValidationResult validateEmployeeName(Field field, Object object)
{
	String nameFromXML = (String)object;
	ValidationResult result = new ValidationResult(true);
	if(nameFromXML.trim().isEmpty())
	{
		result = new ValidationResult(false);
		result.setIfInvalidMessage("Name in XML is empty");
		result.setSeverity(ValidationResult.SEVERITY.STOP);
		// You can use SEVERITY.CONTINUE to continue with the execution
		//result.setSeverity(ValidationResult.SEVERITY.CONTINUE);
		
	}
	return result;
}

3. You can get result of validation using BabyCorn XML APIs

	Employees employees = new Employees();
	BabyCornXML babyCornXML = new BabyCornXML("Employees.xml",employees);
	Validator validator =babyCornXML.getValidator();
	validator.getValidationList();
	System.out.println("validation list "+validator);

Check complete example here Employees.java

Note : For field type String,Char,Boolean 2nd method parameter object could be cast to String and for Double,float,Long parameters object could be cast to Double before using. Return value setIfInvalidValue(returnValue) should be same as type of the field.

Validator to pre process the field values:

Validator can be used to pre process the value. For example: In Employees.java example, if department is not a IT,Finance or Manufacturing then UNKNOWN_DEPARTMENT will be set on the field.

public ValidationResult validateDepartment(Field field, Object object)
{
	String[] departments = {"IT","Finance","Manufacturing"};
	
	String departmentFromXML = (String)object;
	ValidationResult result = new ValidationResult(true);
	if(!Arrays.asList(departments).contains(departmentFromXML))
	{
		result = new ValidationResult(false);
		result.setIfInvalidValue("UNKNOWN_DEPARTMENT");
	}
	return result;
} 

BabyCorn XML APIs:

BabyCorn XML can also be used as XML DOM APIs

public void testAPIs() throws Exception
{
	BabyCornXML babyCornXML = new BabyCornXML("D:\Nilesh\Students.xml");
		
	Document doc= babyCornXML.getDocumentRoot();
		
	NodeList nodeList = doc.getElementsByTagName("lastYearGrade");  
		
	Node node = nodeList.item(0);  
	
	System.out.println("lastYearGrade:" + node.getTextContent());
}