JarCasting
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:
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:
- Add BabyCorn XML jar to your build as specified in above options.
- Create a Java class with fields and annotate it using XPath as per your XML file.
- 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:
- Add
@BabyCornXMLValidation(validationMethod = "validateEmployeeName")annotation on the field. HerevalidateEmployeeNameis a java method, where validation code will be written.
public class Employees {
@BabyCornXMLValidation(validationMethod = "validateEmployeeName")
@BabyCornXMLField(xPath = "employees/employee/name")
public String name;
}
- Write a validation method
validateEmployeeNamein 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;
}
- 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,Boolean2nd method parameterobjectcould be cast toStringand forDouble,float,Longparametersobjectcould be cast toDoublebefore using. Return valuesetIfInvalidValue(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());
}