added a demonstration class: integrate the YaCy search results in own applications

This class requests a YaCy peer remotely and produces search result objects.
The class was implemented in such a way that it is as short as possible. To get a
better integration of search results, use the cora package.
This class is fully stand-alone, it does not need any other external library other than already contained in JRE.

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@7173 6c8d7289-2bf4-0310-a012-ef5d649a1542

source/net/yacy/YaCySearchClient.java

@@ -0,0 +1,112 @@
+/**
+ *  YaCySearchClient
+ *  an interface for Adaptive Replacement Caches
+ *  Copyright 2010 by Michael Peter Christen, mc@yacy.net, Frankfurt a. M., Germany
+ *  First released 20.09.2010 at http://yacy.net
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *  
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *  
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program in the file lgpl21.txt
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.yacy;
+
+import java.io.*;
+import java.net.*;
+import java.util.*;
+
+import javax.xml.parsers.*;
+import org.w3c.dom.*;
+import org.xml.sax.*;
+
+/**
+ * most simple rss reader application for YaCy search result retrieval
+ * this is an example application that you can use to integrate YaCy search results in your own java applications
+ */
+public class YaCySearchClient {
+
+    /*
+     * YaCy Search Results are produced in Opensearch format which is basically RSS.
+     * The YaCy Search Result API Client is therefore implemented as a simple RSS reader.
+     */
+    private String host, query;
+    private int port, offset;
+    
+    public YaCySearchClient(String host, int port, String query) {
+        this.host = host; this.port = port; this.offset = -10; this.query = query;
+    }
+    
+    public SearchResult next() throws IOException {
+        this.offset += 10; // you may call this again and get the next results
+        return new SearchResult();
+    }
+    
+    public class SearchResult extends ArrayList<RSSEntry> {
+        private static final long serialVersionUID = 1337L;
+        public SearchResult() throws IOException {
+            URL url;
+            Document doc;
+            String u =
+                "http://" + host + ":" + port + "/yacysearch.rss?verify=false" +
+                "&startRecord=" + offset + "&maximumRecords=10&resource=local" +
+                "&query=" + query.replaceAll(" ", "+");
+            try { url = new URL(u); } catch (MalformedURLException e) { throw new IOException (e); }
+            try { doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(url.openStream()); }
+            catch (ParserConfigurationException e) { throw new IOException (e); }
+            catch (SAXException e) { throw new IOException (e); }
+            NodeList nodes = doc.getElementsByTagName("item");
+            for (int i = 0; i < nodes.getLength(); i++)
+                this.add(new RSSEntry((Element) nodes.item(i)));
+        }
+        public String toString() {
+            StringBuilder sb = new StringBuilder();
+            for (RSSEntry entry: this) sb.append(entry.toString());
+            return sb.toString();
+        }
+    }
+
+    public static class RSSEntry {
+        String title, link;
+        public RSSEntry(Element element) {
+            title = val(element, "title", "");
+            link  = val(element, "link", "");
+        }
+        private String val(Element parent, String label, String dflt) {
+            Element e = (Element) parent.getElementsByTagName(label).item(0);
+            Node child = e.getFirstChild();
+            return (child instanceof CharacterData) ?
+                    ((CharacterData) child).getData() : dflt;
+        }
+        public String toString() {
+            return "Title : " + title + "\nLink  : " + link + "\n";
+        }
+    }
+    
+    /**
+     * Call the main method with one argument, the query string
+     * search results are then simply printed out.
+     * Multiple search requests can be submitted by adding more call arguments.
+     * Use this method as stub for an integration in your own programs
+     */
+    public static void main(String[] args) {
+        for (String query: args) try {
+            long t = System.currentTimeMillis();
+            YaCySearchClient search = new YaCySearchClient("localhost", 8080, query);
+            System.out.println("Search result for '" + query + "':");
+            System.out.print(search.next().toString()); // get 10 results; you may repeat this for next 10
+            System.out.println("Search Time: " + (System.currentTimeMillis() - t) + " milliseconds\n");
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}