// Copyright 2008 The Android Open Source Project
package com.google.wireless.gdata.parser.xml;
import com.google.wireless.gdata.data.Entry;
import com.google.wireless.gdata.data.Feed;
import com.google.wireless.gdata.data.StringUtils;
import com.google.wireless.gdata.data.XmlUtils;
import com.google.wireless.gdata.parser.GDataParser;
import com.google.wireless.gdata.parser.ParseException;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import java.io.IOException;
import java.io.InputStream;
/**
* {@link GDataParser} that uses an {@link XmlPullParser} to parse a GData feed.
*/
// NOTE: we do not perform any validity checks on the XML.
public class XmlGDataParser implements GDataParser {
/** Namespace URI for Atom */
public static final String NAMESPACE_ATOM_URI =
"http://www.w3.org/2005/Atom";
public static final String NAMESPACE_OPENSEARCH = "openSearch";
public static final String NAMESPACE_OPENSEARCH_URI =
"http://a9.com/-/spec/opensearchrss/1.0/";
/** Namespace prefix for GData */
public static final String NAMESPACE_GD = "gd";
/** Namespace URI for GData */
public static final String NAMESPACE_GD_URI =
"http://schemas.google.com/g/2005";
private final InputStream is;
private final XmlPullParser parser;
private boolean isInBadState;
/**
* Creates a new XmlGDataParser for a feed in the provided InputStream.
* @param is The InputStream that should be parsed.
* @throws ParseException Thrown if an XmlPullParser could not be created
* or set around this InputStream.
*/
public XmlGDataParser(InputStream is, XmlPullParser parser)
throws ParseException {
this.is = is;
this.parser = parser;
this.isInBadState = false;
if (this.is != null) {
try {
this.parser.setInput(is, null /* encoding */);
} catch (XmlPullParserException e) {
throw new ParseException("Could not create XmlGDataParser", e);
}
}
}
/*
* (non-Javadoc)
* @see com.google.wireless.gdata.parser.GDataParser#init()
*/
public final Feed init() throws ParseException {
int eventType;
try {
eventType = parser.getEventType();
} catch (XmlPullParserException e) {
throw new ParseException("Could not parse GData feed.", e);
}
if (eventType != XmlPullParser.START_DOCUMENT) {
throw new ParseException("Attempting to initialize parsing beyond "
+ "the start of the document.");
}
try {
eventType = parser.next();
} catch (XmlPullParserException xppe) {
throw new ParseException("Could not read next event.", xppe);
} catch (IOException ioe) {
throw new ParseException("Could not read next event.", ioe);
}
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
String name = parser.getName();
if ("feed".equals(name)) {
try {
return parseFeed();
} catch (XmlPullParserException xppe) {
throw new ParseException("Unable to parse <feed>.",
xppe);
} catch (IOException ioe) {
throw new ParseException("Unable to parse <feed>.",
ioe);
}
}
break;
default:
// ignore
break;
}
try {
eventType = parser.next();
} catch (XmlPullParserException xppe) {
throw new ParseException("Could not read next event.", xppe);
} catch (IOException ioe) {
throw new ParseException("Could not read next event." , ioe);
}
}
throw new ParseException("No <feed> found in document.");
}
/**
* Returns the {@link XmlPullParser} being used to parse this feed.
*/
protected final XmlPullParser getParser() {
return parser;
}
/**
* Creates a new {@link Feed} that should be filled with information about
* the feed that will be parsed.
* @return The {@link Feed} that should be filled.
*/
protected Feed createFeed() {
return new Feed();
}
/**
* Creates a new {@link Entry} that should be filled with information about
* the entry that will be parsed.
* @return The {@link Entry} that should be filled.
*/
protected Entry createEntry() {
return new Entry();
}
/**
* Parses the feed (but not any entries).
*
* @return A new {@link Feed} containing information about the feed.
* @throws XmlPullParserException Thrown if the XML document cannot be
* parsed.
* @throws IOException Thrown if the {@link InputStream} behind the feed
* cannot be read.
*/
private final Feed parseFeed() throws XmlPullParserException, IOException {
Feed feed = createFeed();
// parsing <feed>
// not interested in any attributes -- move onto the children.
int eventType = parser.next();
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
String name = parser.getName();
if ("totalResults".equals(name)) {
feed.setTotalResults(StringUtils.parseInt(
XmlUtils.extractChildText(parser), 0));
} else if ("startIndex".equals(name)) {
feed.setStartIndex(StringUtils.parseInt(
XmlUtils.extractChildText(parser), 0));
} else if ("itemsPerPage".equals(name)) {
feed.setItemsPerPage(StringUtils.parseInt(
XmlUtils.extractChildText(parser), 0));
} else if ("title".equals(name)) {
feed.setTitle(XmlUtils.extractChildText(parser));
} else if ("id".equals(name)) {
feed.setId(XmlUtils.extractChildText(parser));
} else if ("updated".equals(name)) {
feed.setLastUpdated(XmlUtils.extractChildText(parser));
} else if ("category".equals(name)) {
String category =
parser.getAttributeValue(null /* ns */, "term");
if (!StringUtils.isEmpty(category)) {
feed.setCategory(category);
}
String categoryScheme =
parser.getAttributeValue(null /* ns */, "scheme");
if (!StringUtils.isEmpty(categoryScheme)) {
feed.setCategoryScheme(categoryScheme);
}
} else if ("entry".equals(name)) {
// stop parsing here.
// TODO: pay attention to depth?
return feed;
} else {
handleExtraElementInFeed(feed);
}
break;
default:
break;
}
eventType = parser.next();
}
// if we get here, we have a feed with no entries.
return feed;
}
/**
* Hook that allows extra (service-specific) elements in a <feed> to
* be parsed.
* @param feed The {@link Feed} being filled.
*/
protected void handleExtraElementInFeed(Feed feed)
throws XmlPullParserException, IOException {
// no-op in this class.
}
/*
* (non-Javadoc)
* @see com.google.wireless.gdata.parser.GDataParser#hasMoreData()
*/
public boolean hasMoreData() {
if (isInBadState) {
return false;
}
try {
int eventType = parser.getEventType();
return (eventType != XmlPullParser.END_DOCUMENT);
} catch (XmlPullParserException xppe) {
return false;
}
}
/*
* (non-Javadoc)
* @see com.google.wireless.gdata.parser.GDataParser#readNextEntry
*/
public Entry readNextEntry(Entry entry) throws ParseException, IOException {
if (!hasMoreData()) {
throw new IllegalStateException("you shouldn't call this if hasMoreData() is false");
}
int eventType;
try {
eventType = parser.getEventType();
} catch (XmlPullParserException e) {
throw new ParseException("Could not parse entry.", e);
}
if (eventType != XmlPullParser.START_TAG) {
throw new ParseException("Expected event START_TAG: Actual event: "
+ XmlPullParser.TYPES[eventType]);
}
String name = parser.getName();
if (!"entry".equals(name)) {
throw new ParseException("Expected <entry>: Actual element: "
+ "<" + name + ">");
}
if (entry == null) {
entry = createEntry();
} else {
entry.clear();
}
try {
parser.next();
handleEntry(entry);
entry.validate();
} catch (ParseException xppe1) {
try {
if (hasMoreData()) skipToNextEntry();
} catch (XmlPullParserException xppe2) {
// squelch the error -- let the original one stand.
// set isInBadState to ensure that the next call to hasMoreData() will return false.
isInBadState = true;
}
throw new ParseException("Could not parse <entry>, " + entry, xppe1);
} catch (XmlPullParserException xppe1) {
try {
if (hasMoreData()) skipToNextEntry();
} catch (XmlPullParserException xppe2) {
// squelch the error -- let the original one stand.
// set isInBadState to ensure that the next call to hasMoreData() will return false.
isInBadState = true;
}
throw new ParseException("Could not parse <entry>, " + entry, xppe1);
}
return entry;
}
/**
* Parses a GData entry. You can either call {@link #init()} or
* {@link #parseStandaloneEntry()} for a given feed.
*
* @return The parsed entry.
* @throws ParseException Thrown if the entry could not be parsed.
*/
public Entry parseStandaloneEntry() throws ParseException, IOException {
Entry entry = createEntry();
int eventType;
try {
eventType = parser.getEventType();
} catch (XmlPullParserException e) {
throw new ParseException("Could not parse GData entry.", e);
}
if (eventType != XmlPullParser.START_DOCUMENT) {
throw new ParseException("Attempting to initialize parsing beyond "
+ "the start of the document.");
}
try {
eventType = parser.next();
} catch (XmlPullParserException xppe) {
throw new ParseException("Could not read next event.", xppe);
} catch (IOException ioe) {
throw new ParseException("Could not read next event.", ioe);
}
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
String name = parser.getName();
if ("entry".equals(name)) {
try {
parser.next();
handleEntry(entry);
return entry;
} catch (XmlPullParserException xppe) {
throw new ParseException("Unable to parse <entry>.",
xppe);
} catch (IOException ioe) {
throw new ParseException("Unable to parse <entry>.",
ioe);
}
}
break;
default:
// ignore
break;
}
try {
eventType = parser.next();
} catch (XmlPullParserException xppe) {
throw new ParseException("Could not read next event.", xppe);
}
}
throw new ParseException("No <entry> found in document.");
}
/**
* Skips the rest of the current entry until the parser reaches the next entry, if any.
* Does nothing if the parser is already at the beginning of an entry.
*/
protected void skipToNextEntry() throws IOException, XmlPullParserException {
if (!hasMoreData()) {
throw new IllegalStateException("you shouldn't call this if hasMoreData() is false");
}
int eventType = parser.getEventType();
// skip ahead until we reach an <entry> tag.
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
if ("entry".equals(parser.getName())) {
return;
}
break;
}
eventType = parser.next();
}
}
/**
* Parses the current entry in the XML document. Assumes that the parser
* is currently pointing just after an <entry>.
*
* @param entry The entry that will be filled.
* @throws XmlPullParserException Thrown if the XML cannot be parsed.
* @throws IOException Thrown if the underlying inputstream cannot be read.
*/
protected void handleEntry(Entry entry)
throws XmlPullParserException, IOException, ParseException {
int eventType = parser.getEventType();
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
// TODO: make sure these elements are at the expected depth.
String name = parser.getName();
if ("entry".equals(name)) {
// stop parsing here.
return;
} else if ("id".equals(name)) {
entry.setId(XmlUtils.extractChildText(parser));
} else if ("title".equals(name)) {
entry.setTitle(XmlUtils.extractChildText(parser));
} else if ("link".equals(name)) {
String rel =
parser.getAttributeValue(null /* ns */, "rel");
String type =
parser.getAttributeValue(null /* ns */, "type");
String href =
parser.getAttributeValue(null /* ns */, "href");
if ("edit".equals(rel)) {
entry.setEditUri(href);
} else if (("alternate").equals(rel) && ("text/html".equals(type))) {
entry.setHtmlUri(href);
} else {
handleExtraLinkInEntry(rel,
type,
href,
entry);
}
} else if ("summary".equals(name)) {
entry.setSummary(XmlUtils.extractChildText(parser));
} else if ("content".equals(name)) {
// TODO: parse the type
entry.setContent(XmlUtils.extractChildText(parser));
} else if ("author".equals(name)) {
handleAuthor(entry);
} else if ("category".equals(name)) {
String category =
parser.getAttributeValue(null /* ns */, "term");
if (category != null && category.length() > 0) {
entry.setCategory(category);
}
String categoryScheme =
parser.getAttributeValue(null /* ns */, "scheme");
if (categoryScheme != null && category.length() > 0) {
entry.setCategoryScheme(categoryScheme);
}
} else if ("published".equals(name)) {
entry.setPublicationDate(
XmlUtils.extractChildText(parser));
} else if ("updated".equals(name)) {
entry.setUpdateDate(XmlUtils.extractChildText(parser));
} else if ("deleted".equals(name)) {
entry.setDeleted(true);
} else {
handleExtraElementInEntry(entry);
}
break;
default:
break;
}
eventType = parser.next();
}
}
private void handleAuthor(Entry entry)
throws XmlPullParserException, IOException {
int eventType = parser.getEventType();
String name = parser.getName();
if (eventType != XmlPullParser.START_TAG ||
(!"author".equals(parser.getName()))) {
// should not happen.
throw new
IllegalStateException("Expected <author>: Actual element: <"
+ parser.getName() + ">");
}
eventType = parser.next();
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
name = parser.getName();
if ("name".equals(name)) {
String authorName = XmlUtils.extractChildText(parser);
entry.setAuthor(authorName);
} else if ("email".equals(name)) {
String email = XmlUtils.extractChildText(parser);
entry.setEmail(email);
}
break;
case XmlPullParser.END_TAG:
name = parser.getName();
if ("author".equals(name)) {
return;
}
default:
// ignore
}
eventType = parser.next();
}
}
/*
* (non-Javadoc)
* @see com.google.wireless.gdata.parser.GDataParser#close()
*/
public void close() {
if (is != null) {
try {
is.close();
} catch (IOException ioe) {
// ignore
}
}
}
/**
* Hook that allows extra (service-specific) elements in an <entry>
* to be parsed.
* @param entry The {@link Entry} being filled.
*/
protected void handleExtraElementInEntry(Entry entry)
throws XmlPullParserException, IOException, ParseException {
// no-op in this class.
}
/**
* Hook that allows extra (service-specific) <link>s in an entry to be
* parsed.
* @param rel The rel attribute value.
* @param type The type attribute value.
* @param href The href attribute value.
* @param entry The {@link Entry} being filled.
*/
protected void handleExtraLinkInEntry(String rel,
String type,
String href,
Entry entry)
throws XmlPullParserException, IOException {
// no-op in this class.
}
}
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