Locating Specific Attributes in Digester - Java

Question

I'm using the Apache Commons Digester and trying to locate a particular tag in the structure to include in the object.

<parent>

<image size="small">some url</image>

<image size="medium">some url</image>

<image size="large">some url</image>

<image size="huge">some url</image>

</parent>

I really only want the medium image to be included in my partent object but I'm not sure how I would do that.

Right now I'm using digester.addBeanPropertySetter(PathToParent+"/image","image"); but this gets updated for every image tag (as it should).

Ideally I would like something like digester.addBeanPropertySetter(PathToParent+"/image/medium","image"); but you can't do that.

score 2 · Accepted Answer · answered Dec 05 '10 at 17:53

I omitted generic getters/setters.

  public class Parent {

    private Image image;

    public void setImage(Image image) {
      if ("medium".equals(image.getSize())) {
        this.image = image;
      }
    }

  }

  public class Image {

    private String size;
    private String url;
  }

  public static void main(String[] args) throws IOException, SAXException {
    String s = "<parent>" 
        + "<image size='small'>some url1</image>"
        + "<image size='medium'>some url2</image>"
        + "<image size='large'>some url3</image>"
        + "<image size='huge'>some url4</image>"
        + "</parent>";

    Digester digester = new Digester();

    digester.addObjectCreate("parent", Parent.class);
    digester.addFactoryCreate("parent/image", new ImageCreationFactory());
    digester.addBeanPropertySetter("parent/image", "url");
    digester.addSetNext("parent/image", "setImage");
    Parent p = (Parent) digester.parse(new StringReader(s));
  }

  public class ImageCreationFactory implements ObjectCreationFactory {

    public Object createObject(Attributes attributes) throws Exception {
      Image i = new Image();
      i.setSize(attributes.getValue("size"));
      return i;
    }

  }

Thanks for the ideas Liviu. I ended up just reading the attribute value as well as the bean property. If the size was set to 'medium' a boolean was set enabling the overwrite of my image string value. — smith324, Dec 06 '10 at 01:08

Mike · Answer 2 · 2011-02-24T12:35:14.537

I actually figured this out using the xmlpullparser - here is the code to get the image attribute "large" only and ignore the rest - it's the last "if" in the case statement.

public class XmlPullFeedParser extends BaseFeedParser {

public XmlPullFeedParser(String feedUrl) {
    super(feedUrl);
}

public ArrayList<Message> parse() {
    ArrayList<Message> messages = null;
    XmlPullParser parser = Xml.newPullParser();
    try {
        // auto-detect the encoding from the stream
        parser.setInput(this.getInputStream(), null);
        int eventType = parser.getEventType();
        Message currentMessage = null;
        boolean done = false;
        while (eventType != XmlPullParser.END_DOCUMENT && !done){
            String name = null;
            String attrib = null;
            switch (eventType){
                case XmlPullParser.START_DOCUMENT:
                    messages = new ArrayList<Message>();
                    break;
                case XmlPullParser.START_TAG:
                    name = parser.getName();
                    attrib = parser.getAttributeValue(0);
                    if (name.equalsIgnoreCase(EVENT)){
                        currentMessage = new Message();
                    } else if (currentMessage != null){
                        if (name.equalsIgnoreCase(WEBSITE)){
                            currentMessage.setWebsite(parser.nextText());
                        } else if (name.equalsIgnoreCase(DESCRIPTION)){
                            currentMessage.setDescription(parser.nextText());
                        } else if (name.equalsIgnoreCase(START_DATE)){
                            currentMessage.setDate(parser.nextText());
                        } else if (name.equalsIgnoreCase(TITLE)){
                            currentMessage.setTitle(parser.nextText());
                        } else if (name.equalsIgnoreCase(HEADLINER)){
                            currentMessage.setHeadliner(parser.nextText());
                        } else if ((name.equalsIgnoreCase(IMAGE)) && (attrib.equalsIgnoreCase("large"))) {
                            currentMessage.setImage(parser.nextText());
                        }   
                    }
                    break;
                case XmlPullParser.END_TAG:
                    name = parser.getName();
                    if (name.equalsIgnoreCase(EVENT) && currentMessage != null){
                        messages.add(currentMessage);
                    } else if (name.equalsIgnoreCase(EVENTS)){
                        done = true;
                    }
                    break;
            }
            eventType = parser.next();
        }
    } catch (Exception e) {
        Log.e("AndroidNews::PullFeedParser", e.getMessage(), e);
        throw new RuntimeException(e);
    }
    return messages;
}

}

score 0 · Answer 3 · answered Dec 05 '10 at 07:42

0

I do not think that it is possible. You have to write your own code to perform this kind of filtering.

But it is very simple. If you wish to create clean code write class named ImageAccessor with method getImage(String size). This method will get the data from digester and compare it with predefined size string (or pattern).

answered Dec 05 '10 at 07:42

AlexR

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I'm still unclear on how I can access both the the attribute and the data between the tags at the same time. So when the url gets set in the ImageAccessor class how does it know what size it is? – smith324 Dec 05 '10 at 17:20

Locating Specific Attributes in Digester - Java

3 Answers3