Read XML String using StAX

Question

I am using stax for the first time to parse an XML String. I have found some examples but can\'t get my code to work. This is the latest version of my code:

Answer 1

Here is an example with XMLStreamReader:

   XMLInputFactory inputFactory = XMLInputFactory.newInstance();
   Map<String, String> elements = new HashMap<>();

try {
   XMLStreamReader xmlReader = inputFactory.createXMLStreamReader(file);
   String elementValue = "";
   
   while (xmlReader.hasNext()) {
      int xmlEventType = xmlReader.next();
      
      switch (xmlEventType) {  
          // Check for Start Elements
          case XMLStreamConstants.START_ELEMENT:
              
              //Get current Element Name
              String elementName = xmlReader.getLocalName();
              
              if(elementName.equals("td")) {
              //Get Elements Value
              elementValue = xmlReader.getElementText();
              }
              
              //Add the new Start Element to the Map
              elements.put(elementName, elementValue);                
              break;
          default:
             break;
          }    
   }
   //Close Session
   xmlReader.close();        
} catch (Exception e) {
    log.error(e.getMessage(), e);
}

Answer 2

I faced a similar issue as I was getting "IllegalStateException: Not a textual event" message When I looked through your code I figured out that if you had a condition:

if (event == XMLStreamConstants.START_ELEMENT){
....
addressId = reader.getText(); // it throws exception here
....
}

(Please note: StaXMan did point out this in his answer!)

This happens since to fetch text, XMLStreamReader instance must have encountered 'XMLStreamConstants.CHARACTERS' event!

There maybe a better way to do this...but this is a quick and dirty fix (I have only shown lines of code that may be of interest) Now to make this happen modify your code slightly:

// this will tell the XMLStreamReader that it is appropriate to read the text
boolean pickupText = false

while(reader.hasNext()){

if (event == XMLStreamConstants.START_ELEMENT){
   if( (reader.getLocalName().equals(STATUS) )
   || ( (reader.getLocalName().equals(STATUS) )
   || ((reader.getLocalName().equals(STATUS) ))
         // indicate the reader that it has to pick text soon!
     pickupText = true;
   }
}else if (event == XMLStreamConstants.CHARACTERS){
  String textFromXML = reader.getText();
  // process textFromXML ...

  //...

  //set pickUpText false
  pickupText = false;

 }    

}

Hope that helps!

Answer 3

I found a solution that uses XMLEventReader instead of XMLStreamReader:

public MyObject parseXML(String xml)
    throws XMLStreamException, UnsupportedEncodingException
{
    byte[] byteArray = xml.getBytes("UTF-8");
    ByteArrayInputStream inputStream = new ByteArrayInputStream(byteArray);
    XMLInputFactory inputFactory = XMLInputFactory.newInstance();
    XMLEventReader reader = inputFactory.createXMLEventReader(inputStream);

    MyObject object = new MyObject();

    while (reader.hasNext())
    {
        XMLEvent event = (XMLEvent) reader.next();

        if (event.isStartElement())
        {
            StartElement element = event.asStartElement();

            if (element.getName().getLocalPart().equals("ElementOne"))
            {
                event = (XMLEvent) reader.next();

                if (event.isCharacters())
                {
                     String elementOne = event.asCharacters().getData();
                     object.setElementOne(elementOne);
                }
                continue;
            }
            if (element.getName().getLocalPart().equals("ElementTwo"))
            {
                event = (XMLEvent) reader.next();
                if (event.isCharacters())
                {
                     String elementTwo = event.asCharacters().getData();
                     object.setElementTwo(elementTwo);
                }
                continue;
            }
        }
    }

    return object;
}

I would still be interested in seeing a solution using XMLStreamReader.

Answer 4

Make sure you read javadocs for Stax: since it is fully streaming parsing mode, only information contained by the current event is available. There are some exceptions, however; getElementText() for example must start at START_ELEMENT, but will then try to combine all textual tokens from inside current element; and when returning, it will point to matching END_ELEMENT.

Conversely, getText() on START_ELEMENT will not returning anything useful (since START_ELEMENT refers to tag, not child text tokens/nodes 'inside' start/end element pair). If you want to use it instead, you have to explicitly move cursor in stream by calling streamReader.next(); whereas getElementText() does it for you.

So what is causing the error? After you have consumed all start/end-element pairs, next token will be END_ELEMENT (matching whatever was the parent tag). So you must check for the case where you get END_ELEMENT, instead of yet another START_ELEMENT.