XML parsing using Castor

Put the castor-1.2.jar in you lib folder.
This is object to xml mapping.
 Example is given,
In this Students object is mapped to an xml.Each tag is mapped to different nodes in the XML.

Students.java
/**
 *
 */
package com.jijo;

import java.util.ArrayList;
import java.util.List;

/**
 * @author jijo
 *
 */
public class Students {
    private List<Student> students = new ArrayList<Student>();

    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }
}

Student.java

package com.jijo;

public class Student {
    private String rollNo;
    private String name;
    private String className;
    public String getRollNo() {
        return rollNo;
    }
    public void setRollNo(String rollNo) {
        this.rollNo = rollNo;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getClassName() {
        return className;
    }
    public void setClassName(String className) {
        this.className = className;
    }
}







studentmapping.xml

 <?xml version="1.0"?>
<mapping>
    <class name="com.jijo.Students">
        <field name="students" type="com.jijo.Student" collection="collection">
            <bind-xml name="student" />    <!-- bind xml tag name -->
        </field>
    </class>  
  
    <class name="com.jijo.Student">
        <!--
        <field name="regNo" type="string">
            <bind-xml name="regNo" node="attribute" /> attribute parsing
        </field>
        -->
        <field name="rollNo" type="string">
            <bind-xml name="rollno"/>
        </field>
        <field name="name" type="string">
            <bind-xml name="name"/>
        </field>
      
        <field name="className" type="string">
            <bind-xml name="classname" />
        </field>
    </class>
</mapping>



XmlUtil.java
/**
 *
 */
package com.jijo;

import java.io.ByteArrayInputStream;
import java.io.FileReader;
import java.io.UnsupportedEncodingException;
import java.net.URL;

import org.exolab.castor.mapping.Mapping;
import org.exolab.castor.mapping.MappingException;
import org.exolab.castor.xml.Unmarshaller;
import org.xml.sax.InputSource;



/**
 * @author jijo
 *
 */
public class XmlUtil {
    /**
     * This method will convert the data got from the data source to the appropriate
     * form for the next process.
     *
     * @param className
     * @param xmlFileName
     * @param mappingFileName
     * @throws Exception
     * @throws MappingException
     */
    public Object xmltoObject(String className, String xmlFileName, String mappingFileName) {
        Object obj = null;
        FileReader reader = null;
        try {

            // Load the mapping information from the file                               
            URL mappingURL =  getClass().getClassLoader().getResource(mappingFileName);                                               

            Mapping mapping=new Mapping();                                       
            mapping.loadMapping(mappingURL);                                       

            // Create a Reader to the file to unmarshal from
            reader = new FileReader(xmlFileName);

            // Unmarshal the data
            Unmarshaller unmarshaller = new Unmarshaller(Class
                    .forName(className));
            unmarshaller.setMapping(mapping);

            obj = (Object) unmarshaller.unmarshal(reader);

        } catch (Exception e) {
            e.printStackTrace();                          
           
        }
        finally {
            try {
                reader.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return obj;
    }
    /**
     * This method is used to cast the xml-string to object
     * @param className
     * @param xmlString
     * @param mappingFileName
     * @return
     */
    public Object xmlStringtoObject(String className,String xmlString,String mappingFileName) {
        ByteArrayInputStream Bis1=null;
        try {
            Bis1 = new ByteArrayInputStream(xmlString.getBytes("UTF-8"));
        } catch (UnsupportedEncodingException e1) {

        }
        InputSource in = new InputSource();
        Object obj = null;
        try {

            // Load the mapping information from the file                               
            URL mappingURL =  getClass().getClassLoader().getResource(mappingFileName);

            Mapping mapping=new Mapping();
            mapping.loadMapping(mappingURL);
            // Create a Reader to the file to unmarshal from
            in.setByteStream(Bis1);
            // Unmarshal the data
            Unmarshaller unmarshaller = new Unmarshaller(Class
                    .forName(className));
            unmarshaller.setMapping(mapping);

            obj = (Object) unmarshaller.unmarshal(in);

        } catch (Exception e) {                                        
            e.printStackTrace();
        }
        finally {
            try {
                Bis1.close();
                Bis1=null;
                in=null;
            } catch (Exception e) {
                e.printStackTrace();                      
            }
        }
        return obj;
    }
}

Main.java










package com.jijo;

import java.util.List;


public class Main {
    public static void main(String[] args) {
        try{
            XmlUtil xmlUtil = new XmlUtil();
            Students obj = (Students) xmlUtil.xmltoObject("com.jijo.Students", "C:/jijo/xml/students.xml", "com/jijo/studentmapping.xml");
            if(obj != null){
                List<Student> students = obj.getStudents();
                if(students != null){
                    System.out.println("not null");
                }
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}




 students.xml
<students>

<student>
<rollno>1</rollno>
<name>Jijo</name>
<classname>10</classname>
</student>

<student>
<rollno>2</rollno>
<name>Mathew</name>
<classname>10</classname>
</student>

<student>
<rollno>3</rollno>
<name>Ajeesh</name>
<classname>10</classname>
</student>

<student>
<rollno>4</rollno>
<name>Prathyush</name>
<classname>10</classname>
</student>

</students>


For more details visit http://www.castor.org.

XML parsing using XPath

XML Parsing using XPath example

 //Student.java
package com.jijo;

public class Student {
    private String rollNo;
    private String name;
    private String className;
    public String getRollNo() {
        return rollNo;
    }
    public void setRollNo(String rollNo) {
        this.rollNo = rollNo;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getClassName() {
        return className;
    }
    public void setClassName(String className) {
        this.className = className;
    }
}


//XPathRead.java
package com.jijo;
/**
 * @author jijo
 *
 */
import java.io.IOException;
import java.io.InputStream;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.xml.sax.SAXException;

public class XPathRead {
     private Document xmlDocument;
        private XPath xPath;
      
        public XPathRead(String xmlFile) {       
            initObjects(xmlFile);
        }
       
        public XPathRead(InputStream inputStream) {
             initObjects(inputStream);
        }
       
        private void initObjects(String xmlFile){       
            try {
                xmlDocument = DocumentBuilderFactory.
                newInstance().newDocumentBuilder().
                parse(xmlFile);           
                xPath =  XPathFactory.newInstance().
                newXPath();
            } catch (IOException ex) {
               ex.printStackTrace();
            } catch (SAXException ex) {
               ex.printStackTrace();
            } catch (ParserConfigurationException ex) {
               ex.printStackTrace();
            }      
        }
       
        private void initObjects(InputStream inputStream){       
            try {
                xmlDocument = DocumentBuilderFactory.
                newInstance().newDocumentBuilder().
                parse(inputStream);           
                xPath =  XPathFactory.newInstance().
                newXPath();
            } catch (IOException ex) {
                ex.printStackTrace();
            } catch (SAXException ex) {
                ex.printStackTrace();
            } catch (ParserConfigurationException ex) {
               ex.printStackTrace();
            }      
        }
       
       
       
        public Object read(String expression,
                QName returnType){
            try {
                XPathExpression xPathExpression =
                xPath.compile(expression);
                return xPathExpression.evaluate
                (xmlDocument, returnType);
            } catch (XPathExpressionException ex) {
                ex.printStackTrace();
                return null;
            }
        }

        public Document getXmlDocument() {
            return xmlDocument;
        }

        public void setXmlDocument(Document xmlDocument) {
            this.xmlDocument = xmlDocument;
        }
}


//XmlParser.java
/**
 *
 */
package com.jijo;

import java.io.ByteArrayInputStream;
import java.util.ArrayList;
import java.util.List;

import javax.xml.xpath.XPathConstants;

import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;



/**
 * @author jijo
 *
 */
public class XmlParser {
    private static XPathRead reader;
    public XmlParser(XPathRead xpathreader) {
        this.reader=xpathreader;
    }

    public static XPathRead getXPathRead(String xmlData){
        XPathRead pathReader = null;
        try{
            ByteArrayInputStream Bis1 = new ByteArrayInputStream(xmlData.getBytes("UTF-8"));
            pathReader=new XPathRead(Bis1);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        return pathReader;
    }
   
    public List<Student>  getStudents(){
        List<Student> students = new ArrayList<Student>();
        try {
            String expression = "/students/student";    //parsing expression       
            NodeList logCurves = (NodeList)reader.read(expression, XPathConstants.NODESET);
            for(int index=0;index<logCurves.getLength();index++){
                NodeList curveDetails = logCurves.item(index).getChildNodes();
                Student student=new Student();       
                for(int curveItemIndex=0;curveItemIndex<curveDetails.getLength();curveItemIndex++){
                    if(curveDetails.item(curveItemIndex).getNodeType()!=Node.TEXT_NODE){                   
                        if(curveDetails.item(curveItemIndex).getNodeName().equals("rollno"))
                            student.setRollNo(curveDetails.item(curveItemIndex).getTextContent());
                        if(curveDetails.item(curveItemIndex).getNodeName().equals("name"))
                            student.setName(curveDetails.item(curveItemIndex).getTextContent());
                        if(curveDetails.item(curveItemIndex).getNodeName().equals("classname"))
                            student.setClassName(curveDetails.item(curveItemIndex).getTextContent());                       

                    }
                }
                students.add(student);
               
            }
        } catch (DOMException e) {           
            e.printStackTrace();
        } catch (Exception e) {           
            e.printStackTrace();
        }
        return students;
    }
}

//Main.java
package com.jijo;

import java.util.List;


public class Main {
    public static void main(String[] args) {
        try{
            /**
             * using xpath
             */
            XPathRead pathRead = new XPathRead("C:/jijo/xml/students.xml");
            XmlParser parser = new  XmlParser(pathRead);
            List<Student> students = parser.getStudents();//contains all students data
                       
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

XML is given
students.xml


<students>

<student>
<rollno>1</rollno>
<name>Jijo</name>
<classname>10</classname>
</student>

<student>
<rollno>2</rollno>
<name>Mathew</name>
<classname>10</classname>
</student>

<student>
<rollno>3</rollno>
<name>Ajeesh</name>
<classname>10</classname>
</student>

<student>
<rollno>4</rollno>
<name>Prathyush</name>
<classname>10</classname>
</student>

</students>

Get submap,firstkey , last key from Map(TreeMap)

TreeMap treeMap = new TreeMap();
//get submap from a index to another index
Map subMap = treeMap.subMap(object, object);

//get  firstKey
Object firstKey = treeMap.firstKey();
 //get last key

Object lastKey = treeMap.lastKey();

                       

Compare two objects using Comparable interface

/**
 * Object class
 */
package com.jijo;
/**
 * @author jijo
 *
 */
public class ComparableExample implements Comparable {
    private String id;
    private String userName;
    private String password;
    private String firstName;
    private String lastName;
   
    public int compareTo(ComparableExample arg0) {
        if(this.userName.equals(arg0.getUserName()))
            return 0;
        else
            return 1;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
   
    @Override
    public boolean equals(Object obj) {
        if(this.getUserName() != null && this.getUserName().equalsIgnoreCase(((ComparableExample )obj).getUserName())){
            return true;
        }
        else{
        return false;
        }
    }
   
    @Override
    public int hashCode() {
        if(this.userName != null){
        return this.userName.hashCode();
    }else{
        return 0;
    }
    }
}


//Main class
package com.jijo;

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List list = new  ArrayList();
        ComparableExample comp = new ComparableExample();
        comp.setUserName("jijo");
        comp.setFirstName("jijo");
        list.add(comp);
       
        ComparableExample comp1 = new ComparableExample();
        comp1.setUserName("mathew");
        comp1.setFirstName("mathew");
        list.add(comp1);
       
        ComparableExample comp2 = new ComparableExample();
        comp2.setUserName("jijo");       
        comp2.setFirstName("jijomathew");       
       
        if(list.contains(comp2)){
            System.out.println("true");//returns true
        }
        else{
            System.out.println("false");
        }
       
        comp1 = new ComparableExample();
        comp1.setUserName("jijomathew");
       
        if(list.contains(comp1)){
            System.out.println("true");
        }
        else{
            System.out.println("false"); //returns false
        }
    }
}