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https://codeberg.org/Mercury-IM/Smack
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Improve parseContent() and parseContentDepth()
The idea is that xml-roundtrip should *never* be expected from a XmlPullParser. So what we need is a method that parses the content of an element without relying on getText() returning text if on START_TAG or END_TAG. This is already done by PubSubs ItemProvider. Also add PacketParserUtils.parseElement() which will return the current element as String and use this method in PubSub's ItemProvider.
This commit is contained in:
Florian Schmaus
parent
26b5bc0212
commit
56222d6ee2
8 changed files with 201 additions and 117 deletions
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@ -44,6 +44,7 @@ import org.jivesoftware.smack.provider.ProviderManager;
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import org.jivesoftware.smack.sasl.SASLMechanism.SASLFailure;
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import org.xmlpull.v1.XmlPullParser;
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import org.xmlpull.v1.XmlPullParserException;
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import org.xmlpull.v1.XmlPullParserFactory;
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/**
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* Utility class that helps to parse packets. Any parsing packets method that must be shared
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@ -54,6 +55,24 @@ import org.xmlpull.v1.XmlPullParserException;
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public class PacketParserUtils {
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private static final Logger LOGGER = Logger.getLogger(PacketParserUtils.class.getName());
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/**
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* Creates a new XmlPullParser suitable for parsing XMPP. This means in particular that
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* FEATURE_PROCESS_NAMESPACES is enabled.
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* <p>
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* Note that not all XmlPullParser implementations will return a String on
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* <code>getText()</code> if the parser is on START_TAG or END_TAG. So you must not rely on this
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* behavior when using the parser.
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* </p>
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*
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* @return A suitable XmlPullParser for XMPP parsing
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* @throws XmlPullParserException
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*/
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public static XmlPullParser newXmppParser() throws XmlPullParserException {
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XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
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parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
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return parser;
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}
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/**
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* Parses a message packet.
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*
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@ -96,7 +115,7 @@ public class PacketParserUtils {
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xmlLang = defaultLanguage;
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}
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String subject = parseContent(parser);
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String subject = parseElementText(parser);
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if (message.getSubject(xmlLang) == null) {
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message.addSubject(xmlLang, subject);
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@ -108,8 +127,8 @@ public class PacketParserUtils {
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xmlLang = defaultLanguage;
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}
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String body = parseContent(parser);
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String body = parseElementText(parser);
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if (message.getBody(xmlLang) == null) {
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message.addBody(xmlLang, body);
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}
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@ -140,29 +159,156 @@ public class PacketParserUtils {
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}
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/**
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* Returns the content of a tag as string regardless of any tags included.
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* Returns the textual content of an element as String.
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* <p>
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* The parser must be positioned on a START_TAG of an element which MUST NOT contain Mixed
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* Content (as defined in XML 3.2.2), or else an XmlPullParserException will be thrown.
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* </p>
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* This method is used for the parts where the XMPP specification requires elements that contain
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* only text or are the empty element.
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*
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* @param parser
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* @return the textual content of the element as String
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* @throws XmlPullParserException
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* @throws IOException
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*/
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public static String parseElementText(XmlPullParser parser) throws XmlPullParserException, IOException {
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assert (parser.getEventType() == XmlPullParser.START_TAG);
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String res;
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if (parser.isEmptyElementTag()) {
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res = "";
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}
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else {
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// Advance to the text of the Element
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int event = parser.next();
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if (event != XmlPullParser.TEXT) {
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throw new XmlPullParserException(
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"Non-empty element tag not followed by text, while Mixed Content (XML 3.2.2) is disallowed");
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}
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res = parser.getText();
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event = parser.next();
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if (event != XmlPullParser.END_TAG) {
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throw new XmlPullParserException(
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"Non-empty element tag contains child-elements, while Mixed Content (XML 3.2.2) is disallowed");
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}
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}
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return res;
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}
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/**
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* Returns the current element as string.
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* <p>
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* The parser must be positioned on START_TAG.
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* </p>
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* Note that only the outermost namespace attributes ("xmlns") will be returned, not nested ones.
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*
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* @param parser the XML pull parser
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* @return the element as string
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* @throws XmlPullParserException
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* @throws IOException
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*/
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public static String parseElement(XmlPullParser parser) throws XmlPullParserException, IOException {
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assert(parser.getEventType() == XmlPullParser.START_TAG);
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return parseContentDepth(parser, parser.getDepth());
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}
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/**
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* Returns the content of a element as string.
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* <p>
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* The parser must be positioned on the START_TAG of the element which content is going to get
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* returned. If the current element is the empty element, then the empty string is returned. If
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* it is a element which contains just text, then just the text is returned. If it contains
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* nested elements (and text), then everything from the current opening tag to the corresponding
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* closing tag of the same depth is returned as String.
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* </p>
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* Note that only the outermost namespace attributes ("xmlns") will be returned, not nested ones.
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*
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* @param parser the XML pull parser
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* @return the content of a tag as string
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* @throws XmlPullParserException if parser encounters invalid XML
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* @throws IOException if an IO error occurs
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*/
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private static String parseContent(XmlPullParser parser)
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public static String parseContent(XmlPullParser parser)
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throws XmlPullParserException, IOException {
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int parserDepth = parser.getDepth();
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return parseContentDepth(parser, parserDepth);
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assert(parser.getEventType() == XmlPullParser.START_TAG);
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if (parser.isEmptyElementTag()) {
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return "";
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}
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// Advance the parser, since we want to parse the content of the current element
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parser.next();
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return parseContentDepth(parser, parser.getDepth());
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}
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/**
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* Returns the content from the current position of the parser up to the closing tag of the
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* given depth. Note that only the outermost namespace attributes ("xmlns") will be returned,
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* not nested ones.
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* <p>
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* This method is able to parse the content with MX- and KXmlParser. In order to achieve
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* this some trade-off has to be make, because KXmlParser does not support xml-roundtrip (ie.
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* return a String on getText() on START_TAG and END_TAG). We are therefore required to work
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* around this limitation, which results in only partial support for XML namespaces ("xmlns"):
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* Only the outermost namespace of elements will be included in the resulting String.
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* </p>
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*
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* @param parser
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* @param depth
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* @return the content of the current depth
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* @throws XmlPullParserException
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* @throws IOException
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*/
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public static String parseContentDepth(XmlPullParser parser, int depth) throws XmlPullParserException, IOException {
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StringBuilder content = new StringBuilder();
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while (!(parser.next() == XmlPullParser.END_TAG && parser.getDepth() == depth)) {
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String text = parser.getText();
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if (text == null) {
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throw new IllegalStateException("Parser should never return 'null' on getText() here");
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XmlStringBuilder xml = new XmlStringBuilder();
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int event = parser.getEventType();
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boolean isEmptyElement = false;
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// XmlPullParser reports namespaces in nested elements even if *only* the outer ones defines
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// it. This 'flag' ensures that when a namespace is set for an element, it won't be set again
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// in a nested element. It's an ugly workaround that has the potential to break things.
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String namespaceElement = null;;
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while (true) {
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if (event == XmlPullParser.START_TAG) {
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xml.halfOpenElement(parser.getName());
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if (namespaceElement == null) {
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String namespace = parser.getNamespace();
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if (StringUtils.isNotEmpty(namespace)) {
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xml.attribute("xmlns", namespace);
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namespaceElement = parser.getName();
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}
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}
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for (int i = 0; i < parser.getAttributeCount(); i++) {
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xml.attribute(parser.getAttributeName(i), parser.getAttributeValue(i));
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}
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if (parser.isEmptyElementTag()) {
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xml.closeEmptyElement();
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isEmptyElement = true;
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}
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else {
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xml.rightAngelBracket();
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}
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}
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content.append(text);
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else if (event == XmlPullParser.END_TAG) {
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if (isEmptyElement) {
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// Do nothing as the element was already closed, just reset the flag
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isEmptyElement = false;
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}
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else {
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xml.closeElement(parser.getName());
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}
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if (namespaceElement != null && namespaceElement.equals(parser.getName())) {
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// We are on the closing tag, which defined the namespace as starting tag, reset the 'flag'
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namespaceElement = null;
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}
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if (parser.getDepth() <= depth) {
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// Abort parsing, we are done
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break;
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}
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}
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else if (event == XmlPullParser.TEXT) {
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xml.append(parser.getText());
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}
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event = parser.next();
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}
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return content.toString();
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return xml.toString();
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}
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/**
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