/*
* Encog(tm) Core v3.0 - Java Version
* http://www.heatonresearch.com/encog/
* http://code.google.com/p/encog-java/
* Copyright 2008-2011 Heaton Research, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.util;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import org.encog.EncogError;
import org.encog.parse.tags.Tag;
import org.encog.parse.tags.read.ReadHTML;
import org.encog.util.http.FormUtility;
/**
* YahooSearch: Perform a search using Yahoo.
*/
public class YahooSearch {
/**
* How many retries.
*/
private static final int MAX_TRIES = 5;
/**
* How long to sleep between retry.
*/
private static final long RETRY_SLEEP = 5000;
/**
* Do a search using the Yahoo search engine. Called internally.
*
* @param url
* The Yahoo URL.
* @return A collection of URL's.
* @throws IOException
* An error occured communicating with Yahoo.
*/
private Collection<URL> doSearch(final URL url) throws IOException {
final Collection<URL> result = new ArrayList<URL>();
// submit the search
final InputStream is = url.openStream();
final ReadHTML parse = new ReadHTML(is);
final StringBuilder buffer = new StringBuilder();
boolean capture = false;
// parse the results
int ch;
while ((ch = parse.read()) != -1) {
if (ch == 0) {
final Tag tag = parse.getTag();
if (tag.getName().equalsIgnoreCase("url")) {
buffer.setLength(0);
capture = true;
} else if (tag.getName().equalsIgnoreCase("/url")) {
result.add(new URL(buffer.toString()));
buffer.setLength(0);
capture = false;
}
} else {
if (capture) {
buffer.append((char) ch);
}
}
}
return result;
}
/**
* Called to extract a list from the specified URL.
*
* @param searchFor
* What to search for.
* @return The URL's found for the specific search.
* @throws IOException
* Error connecting to Yahoo.
*/
public Collection<URL> search(final String searchFor) throws IOException {
Collection<URL> result = null;
// build the URL
final ByteArrayOutputStream bos = new ByteArrayOutputStream();
final FormUtility form = new FormUtility(bos, null);
form.add("appid", "YahooDemo");
form.add("results", "100");
form.add("query", searchFor);
form.complete();
final URL url = new URL(
"http://search.yahooapis.com/WebSearchService/V1/webSearch?"
+ bos.toString());
bos.close();
int tries = 0;
boolean done = false;
while (!done) {
try {
result = doSearch(url);
done = true;
} catch (final IOException e) {
if (tries == YahooSearch.MAX_TRIES) {
throw e;
}
try {
Thread.sleep(YahooSearch.RETRY_SLEEP);
} catch (final InterruptedException e1) {
throw new EncogError("Interrupted");
}
}
tries++;
}
return result;
}
}