Java - Sample Programs.....: April 2013

JAXB

Introduction:

JAXB(Java Architecture for XML Binding) provides API to access and process a XML document

We can read or write XML files using JAXB. Unlike DOM, SAX or StAX parsers to use JAXB the developer need not be aware of XML parsing techniques.

JAXB Implementation:

JAXB API is a set of interfaces for which we have various implementations. As part of Metro there is a project for JAXB providing reference implementation. JSR 222 is developed by JCP for JAXB. Latest version of JAXB as of now is JAXB 2.2.

In this article we use Metro’s JAXB reference implementation. To run the sample code associated, you should download jaxb implementation and the jar files to the classpath.

There are two operations you can perform using JAXB

1. Marshalling :Converting a java object to XML

2. UnMarshalling :Converting a XML to java object

For Marshaling:

@XmlRootElement: This annotation defines root element of XML file.
@XmlType(propOrder = {"list of attributes in order"}):This is used to define order of elements in XML file.This is optional.
@XmlElement:This is used to define element in XML file.It sets name of entity.

@XmlElementWrapper(name = "name to be given to that wrapper"):It generates a wrapper element around XML representation.E.g.In above example, it will generate <bookList> around each <book> element

For Unmarshaling:

Example:

Book.java
package trg.jaxb.bookStore;

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

@XmlRootElement(name="book")
@XmlType(propOrder={"name", "author", "publisher", "isbn"})
public class Book {
   private String name;
   private String author;
   private String isbn;
   private String publisher;

   public Book() {
       super();
   }
   public Book(String name, String author, String isbn, String publisher) {
       super();
       this.name = name;
       this.author = author;
       this.isbn = isbn;
       this.publisher = publisher;
   }
   public String getName() {
       return name;
   }
   @XmlElement(name="title")
   public void setName(String name) {
       this.name = name;
   }
   public String getAuthor() {
       return author;
   }
   public void setAuthor(String author) {
       this.author = author;
   }
   public String getIsbn() {
       return isbn;
   }
   public void setIsbn(String isbn) {
       this.isbn = isbn;
   }
   public String getPublisher() {
       return publisher;
   }
   public void setPublisher(String publisher) {
       this.publisher = publisher;
   }

}

BookStore.java

package trg.jaxb.bookStore;
import java.util.List;

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

@XmlRootElement(name="bookStore", namespace="trg.jaxb.bookStore")
@XmlType(propOrder={"name", "location", "bookList"})
public class BookStore {
    private String name;
    private String location;
    private List<Book> bookList;
    public String getName() {
       return name;
    }
    public void setName(String name) {
       this.name = name;
    }
    public String getLocation() {
       return location;
    }
    public void setLocation(String location) {
       this.location = location;
    }
    @XmlElement(name="book")
    @XmlElementWrapper(name="bookList")
    public List<Book> getBookList() {
       return bookList;
    }
    public void setBookList(List<Book> bookList) {
       this.bookList = bookList;
    }

}

JAXBMarshalDemo.java

package trg.jaxb.bookStore;

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

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBMarshalDemo {
    private static final String BOOKSTORE_XML = "KharadiBookStore.xml";
    public static void main(String[] args) {
       List<Book> bookList = new ArrayList<Book>(4);
       bookList.add(new Book("Stauts 2 In Action", "A. King", "ISBN-0001", "Wrox Pub."));
       bookList.add(new Book("Spring 3 In Action", "B. King", "ISBN-0002", "Apprentice Hall"));
       bookList.add(new Book("Hibernate 3 In Action", "C. King", "ISBN-0003", "Kalyani Pub."));
       bookList.add(new Book("JSF In Action", "D. King", "ISBN-0004", "ABC Pub."));

       BookStore bookStore = new BookStore();
       bookStore.setName("Kharadi Book Store");
       bookStore.setLocation("Kharadi");
       bookStore.setBookList(bookList);
       try {
           JAXBContext jaxbContext = JAXBContext.newInstance(BookStore.class);
           Marshaller marshaller = jaxbContext.createMarshaller();
           marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
           //render the xml tree on console....
           marshaller.marshal(bookStore, System.out);
           //write the xml tree to a file
           marshaller.marshal(bookStore, new File(BOOKSTORE_XML));
       } catch (JAXBException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
    }

}

JAXBUnmarshalDemo.java

package trg.jaxb.bookStore;

import java.io.File;
import java.io.IOException;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

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

public class JAXBUnmarshalDemo {
    private static final String BOOKSTORE_XML = "BookStore.xml";
    public static void main(String[] args) {
        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(BookStore.class);
            System.out.println("Books from .xml file...\n\n");

            Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File("D:\\Sidharth\\Web Services\\workspace - WS\\SidWsTrg_JAXB_BookStore\\BookStore.xml"));
            doc.getDocumentElement().normalize();
            System.out.println("Name : " + doc.getChildNodes().item(0).getChildNodes().item(1).getChildNodes().item(0).getNodeValue());

            Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
            BookStore bookStore = (BookStore) unmarshaller.unmarshal(new File(BOOKSTORE_XML));
            for(Book book : bookStore.getBookList())
                System.out.println("Book -> " + book.getName() + " : " + book.getAuthor() + " : " + book.getPublisher() + " : " + book.getIsbn());
        } catch (JAXBException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ParserConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

Download Link : SidWsTrg_JAXB_BookStore

Generating Java Beans from XML Schema(.xsd files):

Download JAXB RI(say jaxb-ri-2.2.6 from metro)

Set CLASSPATH for jaxb-api.jar, jaxb-impl.jar & jaxb-xjc.jar

Create xsd’s & run the following command:

$xjc [options] <file>.xsd

E.g. ...\workspace - WS\SidWsTrg_JAXB_XSD_To_Bean\src>xjc -p trg.jaxb Employee.xsd

Employee.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:tns="http://trg.jaxb/employee" elementFormDefault="qualified"
    targetNamespace="http://trg.jaxb/employee">
    <xsd:element name="EmployeeDetailsRequest">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element ref="tns:empId" />
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>
    <xsd:element name="EmployeeDetailsResponse">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element name="name" type="xsd:string" />
                <xsd:element name="email" type="xsd:string" />
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>
    <xsd:element name="empId">
        <xsd:simpleType>
            <xsd:restriction base="xsd:string">
                <xsd:pattern value="[a-z]{2}[0-9]{5}" />
            </xsd:restriction>
        </xsd:simpleType>
    </xsd:element>
</xsd:schema>

Run the below mentioned command(N.B. jars must be at classpath):

\workspace - WS\SidWsTrg_JAXB_XSD_To_Bean\src>xjc -p trg.jaxb Employee.xsd

Download Link : SidWsTrg_JAXB_XSD_To_Bean

Java - Sample Programs.....

Monday, 8 April 2013

JAXB Tutorial

JAXB

For Marshaling:

For Unmarshaling: