Reading in XML into Objects

[Ryan Waggoner]

Hi guys,
I am working on a little XML piece and well...

I have this little XML reader method

   
public String loadHouses(String fileLocation) {
		try{
		//Get a new instance of the xml factor
		XMLInputFactory factory = XMLInputFactory.newInstance();
		//Create a read with the fileLocation param passed in
	    Reader fileReader = new FileReader(fileLocation);
	    //Create a new xml read from the factory, with the file reader passed in
	    XMLEventReader reader = factory.createXMLEventReader(fileReader);
	    
	    //While not at end of file
	    while (reader.hasNext()) {
	    	//Create an event as the reader's next even
	        XMLEvent event = reader.nextEvent();
	        //If the event is the start of an element
	        if (event.isStartElement()) {
	          //Grab that element
	          StartElement element = (StartElement) event;
	          //Print out the element Name
	          System.out.println("Start Element: " + element.getName());
	          //Get all attributes of the element
	          Iterator iterator = element.getAttributes();
	          //While not at end of attribute list
	          while (iterator.hasNext()) {
	        	//Create an attribute from the iterators next attribute
	            Attribute attribute = (Attribute) iterator.next();
	            //Get the attribute name
	            QName name = attribute.getName();
	            //Get the attribute value
	            String value = attribute.getValue();
	            //Print out the attribute intfo
	            System.out.println("Attribute name/value: " + name + "/" + value);
	          }
	        }
	        //If the end of an element
	        if (event.isEndElement()) {
	          //Create an element of the end elements
	          EndElement element = (EndElement) event;
	          //Print out the end element
	          System.out.println("End element:" + element.getName());
	        }
	        //If there are characters ever written
	        if (event.isCharacters()) {
	          //Grab the characters from the event
	          Characters characters = (Characters) event;
	          //Print out the txt
	          System.out.println("Text: " + characters.getData());
	        }
	      }
	    
	    
	    return "success";
		}
		
		catch(Exception e)
		{
			log.error("error", e.getMessage());
			return "failure";
		}
	}

 

And this is the XML file I am reading in

    
  <?xml version="1.0" ?> 
- <Houses>
- <House>
  <ownerName>Momo</ownerName> 
  <ownerPhone /> 
  <country /> 
  <state /> 
  <address /> 
  <bedrooms>0</bedrooms> 
  <bathrooms>0</bathrooms> 
  <sqFoot>0</sqFoot> 
  <garage>0</garage> 
  <land>0</land> 
  <fenced>false</fenced> 
  <furnished>false</furnished> 
  <basement /> 
  <sold>false</sold> 
  <image>No way to put in images yet =(</image> 
  </House>
  </Houses>

I want to create an instance of a House, but so far the only way I can do it is, putting a lot of little if statements like:

If (isStartElement && element.name.equals("ownerName")
set ownerName = element.getCharacter

Any suggestions?

Thanks!

[K. Tsang]

I think there is easier way using JAXP (Java API for XML Processing). If you are already using it good.

To make you if statements go away? Why not have a House class? Can't say much without knowing architecture.

[Ryan Waggoner]

Hey sorry,
I do have a house class, and it has all the properties you see in the xml document. I am having troublelinking the document to my house class.

[Hong Anderson]

Have you tried Xstream?

[Campbell Ritchie]

Too difficult a question for us beginners, Moving.

[phil mitchel]

look into JAXB / JAX-WS, unmarshal your XML directly into the objects generated from xjc. you could wirte adaptors to wrap the generated classes to fit your needs or have constructors in your own classes that take the generated objects as args.

if don't already have a proper XSD, you can create the XSD on this site:
http://www.hitsw.com/xml_utilites/

run xjc from the command line, pass the XSD as an argument - or google how to add it as an extrnal tool in eclipse

here's some bare bones code I dug out to show how to marshal / unmarshal

    
package com;

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

import generated.Book;
import generated.Bookstore;
import generated.ObjectFactory;
import generated.Price;
import generated.Title;

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

public class JAXBTest {
	public static void mainT(String [] args){
		new JAXBTest();
	}
	
	JAXBTest(){
		marshal();
		unmarshal();
	}
	
	void marshal(){
		try {
		
			JAXBContext jaxbContext = JAXBContext.newInstance("generated");
			
			Marshaller marshaller = jaxbContext.createMarshaller();
			ObjectFactory factory = new ObjectFactory();
			
			// create bookstore
			Bookstore bookStore = factory.createBookstore();			
			Book book = factory.createBook();
			Title title = factory.createTitle();
			Price price = factory.createPrice();
			
			price.setContent("10:50");
			title.setContent("MyBook");
			title.setLang("Eng");
			
			book.setPrice(price);
			book.setTitle(title);
			
			List<Book> bookList = bookStore.getBook();
			bookList.add(book);
			
			marshaller.marshal(bookStore,System.out);

		} catch (JAXBException e) {
			e.printStackTrace();
		}
	}
	
	void unmarshal(){
		try {
			JAXBContext jaxbContext = JAXBContext.newInstance("generated"); // where generated is the package name of the generated lcasses
			Unmarshaller unMarshaller = jaxbContext.createUnmarshaller();
			
			File f = new File("somefile.xml");
			Bookstore bookStore = (Bookstore)(unMarshaller.unmarshal(f));
			
			for (Book b :bookStore.getBook()){
				System.out.println(b.getTitle().getContent()+"\t"+b.getPrice().getContent());
			}
			
		} catch (JAXBException e) {
			e.printStackTrace();
		}
	}
}

rgds,
Phil

[Ryan Waggoner]

Working wonderfully

Thanks a lot!