foursquare的高效率XML分析器（一）
在分析foursquare的代码时，xml交互数据应该算是最核心的部分，通常理解为sax解析，但我找了半天没有在代码中找到，所以意识到是思路有偏差，重新整理发现用的是分析器（Parser）的方式来处理，并且效率很高
代码如下：
package com.joelapenna.foursquare.parsers;
import com.joelapenna.foursquare.Foursquare;
import com.joelapenna.foursquare.error.FoursquareError;
import com.joelapenna.foursquare.error.FoursquareParseException;
import com.joelapenna.foursquare.types.FoursquareType;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* @author Joe LaPenna ([email protected])
*/
public abstract class AbstractParser<T extends FoursquareType> implements Parser<T> {
private static final Logger LOG = Logger.getLogger(AbstractParser.class.getCanonicalName());
private static final boolean DEBUG = Foursquare.PARSER_DEBUG;
private static XmlPullParserFactory sFactory;
static {
try {
sFactory = XmlPullParserFactory.newInstance();
} catch (XmlPullParserException e) {
throw new IllegalStateException("Could not create a factory");
}
}
abstract protected T parseInner(final XmlPullParser parser) throws IOException,
XmlPullParserException, FoursquareError, FoursquareParseException;
/*
* (non-Javadoc)
* @see com.joelapenna.foursquare.parsers.Parser#parse(java.io.InputStream)
*/
public final T parse(XmlPullParser parser) throws FoursquareParseException, FoursquareError {
try {
if (parser.getEventType() == XmlPullParser.START_DOCUMENT) {
parser.nextTag();
if (parser.getName().equals("error")) {
throw new FoursquareError(parser.nextText());
}
}
return parseInner(parser);
} catch (IOException e) {
if (DEBUG) LOG.log(Level.FINE, "IOException", e);
throw new FoursquareParseException(e.getMessage());
} catch (XmlPullParserException e) {
if (DEBUG) LOG.log(Level.FINE, "XmlPullParserException", e);
throw new FoursquareParseException(e.getMessage());
}
}
public static final XmlPullParser createXmlPullParser(InputStream is) {
XmlPullParser parser;
try {
parser = sFactory.newPullParser();
if (DEBUG) {
StringBuffer sb = new StringBuffer();
if (DEBUG) {
while (true) {
final int ch = is.read();
if (ch < 0) {
break;
} else {
sb.append((char)ch);
}
}
is.close();
LOG.log(Level.FINE, sb.toString());
}
parser.setInput(new StringReader(sb.toString()));
} else {
parser.setInput(is, null);
}
} catch (XmlPullParserException e) {
throw new IllegalArgumentException();
} catch (IOException e) {
throw new IllegalArgumentException();
}
return parser;
}
public static void skipSubTree(XmlPullParser parser) throws XmlPullParserException, IOException {
parser.require(XmlPullParser.START_TAG, null, null);
int level = 1;
while (level > 0) {
int eventType = parser.next();
if (eventType == XmlPullParser.END_TAG) {
--level;
} else if (eventType == XmlPullParser.START_TAG) {
++level;
}
}
}
}