KXML skip SubTree skip Depth

KXML is just the name of XML parsing in J2ME. As I am using it in MiniIM, parsing XMPP and even special markup, I found it useful to skip upto a specific depth of XML tree. Note, the skipSubTree() method in KXMLParser / XMLPullParser API is useful. But it needs that you call it at tag start otherwise it will throw exception. So I introduce skipDepth(depth) idea. You just set your depth upto which you want to skip. It will just eat data upto that.

For example here is a small part of stream,

<?xml version='1.0'?>

<stream:stream xmlns="jabber:client" xmlns:stream="http://etherx.jabber.org/streams" id="1523376107" from="jabber.org" version="1.0" xml:lang="en">

...
...
 <stream:features>
  <mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
   <mechanism>DIGEST-MD5</mechanism>
   <mechanism>PLAIN</mechanism>
  </mechanisms>
  <register xmlns="http://jabber.org/features/iq-register"/>
 </stream:features>

...
...

Here is the simple code to parse the "stream:features",

final void readFeatures() throws IOException {
  String tagName;
  String text;
  parser.nextTag();
  parser.require(KXmlParser.START_TAG, null, PREFIX_FEATURES);
  
  for (; parser.nextTag() != KXmlParser.END_TAG; parser.skipDepth(3)) { /* The features tag is placed at depth 1 */
   /* we are parsing things inside this feature tag */
   tagName = parser.getName();
   if (tagName == null) {
    throw new IllegalStateException("feature is null");
   } else if (tagName.equals(STARTTLS)) {
    /* set a starttls read command */
    SimpleLogger.debug(this, "<" + STARTTLS);
    featuresTLS = true;
   } else if (tagName.equals(MECHANISMS)) {
    /* traverse the mechanisms inside */
    SimpleLogger.info(this, "readFeatures()\t\tparsing mechanisms");
    /* so while inside the mechanisms */
    for (; parser.nextTag() != KXmlParser.END_TAG;parser.skipDepth(5)) {
     tagName = parser.getName();
     if (tagName.equals(MECHANISM)) {
      /* see if the mechanism is PLAIN */
      text = expectText();
      if (text == null) {
       
      } else if (text.equals(PLAIN)) {
       /* say that plain mechanism is found */
       SimpleLogger.info(this, "<" + PLAIN);
       featuresPlain = true;
      } else if(text.equals(DIGEST_MD5)) {
       SimpleLogger.info(this, "<" + DIGEST_MD5);
       featuresDigestMd5 = true;
      }
      /* do not break, go on parsing mechanisms */
     }
    }
   } else if (tagName.equals(BIND)) {
    SimpleLogger.debug(this, "<" + BIND);
    featuresBind = true;
   } else if(tagName.equals(COMPRESSION)) {
    // QUOTE "the ZLIB compression algorithm is mandatory-to-implement"
    featuresZLIB = true;
    /* traverse the mechanisms inside */
    SimpleLogger.info(this, "readFeatures()\t\tparsing compression");
    for (; parser.nextTag() != KXmlParser.END_TAG;parser.skipDepth(5)) {
     tagName = parser.getName();
     if (tagName.equals(METHOD)) {
      String compressionMethod = expectText();
      if(compressionMethod != null && compressionMethod.equals(ZLIB)) {
       featuresZLIB = true;
      }
     }
    }
   } else {
    SimpleLogger.debug(this, "<!" + tagName);
    /* whatever it is just finish the tag */
   }
   SimpleLogger.debug(this, "< next");
  }
  parser.skipDepth(2);  
 }
}

And here is the small method I have added in KXMLParser.

public void skipDepth(int dep) throws IOException,XmlPullParserException {
 int level = getDepth() - dep;
 int eventType = getEventType();
 
 if(eventType != KXmlParser.END_TAG) {
  level++;
 }
 
 while(level > 0) {
  eventType = next();
     if (eventType == KXmlParser.END_TAG) {
  --level;
     }
     else if (eventType == KXmlParser.START_TAG) {
  ++level;
     }
 }
}

I hope it helps :) ..