Java tutorial
/********************************************************************************** * * Copyright (c) 2003, 2004, 2007, 2008 The Sakai Foundation * * Licensed under the Educational Community 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.opensource.org/licenses/ECL-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. * **********************************************************************************/ package edu.indiana.lib.twinpeaks.search; import edu.indiana.lib.twinpeaks.util.*; import org.osid.repository.AssetIterator; import java.io.*; import java.net.*; import java.util.*; import javax.xml.parsers.*; import org.w3c.dom.*; import org.w3c.dom.html.*; import org.xml.sax.*; /** * Result rendering - base class and helpers */ public abstract class SearchResultBase implements SearchResultInterface { private static org.apache.commons.logging.Log _log = LogUtils.getLog(SearchResultBase.class); /** * Parse the search engine response and expose pertinent results */ private ArrayList _itemList; private AssetIterator _assetIterator; private int _start; private int _count; private String _nextPreviewPage; private String _previousPreviewPage; protected String _searchQuery; protected byte _searchResponseBytes[]; protected String _searchResponseString; protected Document _searchResponseDocument; protected String _database; protected String _sessionId; protected String _baseUrl; /** * Constructor */ public SearchResultBase() { super(); } /* * Interface methods */ /** * Save various attributes of the general search request * @param query The QueryBase extension that sent the search request */ public void initialize(QueryBase query) { _searchQuery = query.getRequestParameter("searchString"); _database = query.getRequestParameter("database"); _sessionId = query.getRequestParameter("guid"); _searchResponseString = query.getResponseString(); _searchResponseBytes = query.getResponseBytes(); _searchResponseDocument = parseResponse(); _itemList = new ArrayList(); _start = 1; saveBaseUrl(query.getUrl()); } /** * Add a MatchItem object * @param item MatchItem to add */ public void addItem(MatchItem item) { _itemList.add(item); } /** * Fetch the original query text * @return Search string */ public String getQuery() { return _searchQuery; } /** * Return the starting item number for this search (one based) * @return Starting item number */ public int getSearchStart() { return _start; } /** * Set the starting item number for this search (one based) * @param start Starting item number */ public void setSearchStart(int start) { _start = start; } /** * Set the starting item number for this search (one based) * @param start Starting item number */ public void setSearchStart(String start) { try { _start = Integer.parseInt(start); } catch (NumberFormatException exception) { _log.warn("Invalid number format: " + start); return; } } /** * Return the count of matching items returned * @return Item count */ public int getMatchCount() { return _itemList.size(); } /** * Fetch the "next preview page" reference (used to paginate results * null if none) * @return Next page reference */ public String getNextPreviewPage() { return _nextPreviewPage; } /** * Set the "next preview page" reference * @param reference Next page reference */ public void setNextPreviewPage(String reference) { _nextPreviewPage = reference; } /** * Fetch the "previous preview page" reference (used to paginate results, * null if none) * @return Previous page reference */ public String getPreviousPreviewPage() { return _previousPreviewPage; } /** * Set the "previous preview page" reference * @param reference Previous page reference */ public void setPreviousPreviewPage(String reference) { _previousPreviewPage = reference; } /** * Can this display be paginated (next/previous pages for display)? * @return true if so */ public boolean canPaginate() { return (_previousPreviewPage != null) || (_nextPreviewPage != null); } /** * Get an iterator to the result list * @return SearchResult Iterator */ public Iterator iterator() { return _itemList.iterator(); } /** * Return the MatchItem list as a simple array * @return MatchItem array */ public MatchItem[] toArray() { return (MatchItem[]) _itemList.toArray(new MatchItem[_itemList.size()]); } /** * Return search results as a String * @return Result Document */ public String getSearchResponseString() { return _searchResponseString; } /* * Helpers */ /** * Return search results as a Document * @return Result Document */ public Document getSearchResponseDocument() { return _searchResponseDocument; } /** * Parse the search engine response as HTML. * See <code>initialize()</code> (override as reqired) * @return Response as a DOM Document */ protected Document parseResponse() throws SearchException { try { return DomUtils.parseHtmlBytes(_searchResponseBytes); } catch (Exception exception) { throw new SearchException(exception.toString()); } } /** * Save the request URL base (the server portion only) * @param url Request URL (with or without parameters) */ public void saveBaseUrl(String url) { _baseUrl = HttpTransactionUtils.getServer(url); } /** * Form a full URL (protocol, server, arguments) from a base URL and * provided parameters * @param baseUrl The base (or template) URL * @param urlFragment The (possibly) relative URL to be combined with the base * @return A full URL (as a String) */ public String getFullUrl(String baseUrl, String urlFragment) { String thisUrl = baseUrl; if (thisUrl == null) { thisUrl = _baseUrl; } if (thisUrl != null) { try { URL base = new URL(thisUrl); return new URL(base, urlFragment).toString(); } catch (MalformedURLException exception) { throw new SearchException(exception.toString()); } } return urlFragment; } /** * Form a full URL (protocol, server, arguments) from a provided URL * and a previously provided base URL * @param urlFragment The (possibly) relative URL to be combined with the base * @return A full URL (as a String) */ public String getFullUrl(String urlFragment) { return getFullUrl(null, urlFragment); } /** * Prepend proxy string (if not already present) * @param url Target URL * @param proxy Proxy specification * @return (Possibly) updated URL string */ public String prependProxy(String url, String proxy) { StringBuilder fullUrl; _log.debug("prependProxy: proxy [" + proxy + "] vs. [" + url + "]"); if (StringUtils.isNull(proxy)) { return url; } if (url.startsWith(proxy)) { return url; } fullUrl = new StringBuilder(proxy); fullUrl.append(url); return fullUrl.toString(); } /** * Verify we have the expected number of Elements in a Node list * @param nodeList List of collected Elements * @param expected Number of Elements we expect to see * @return true If we have the expected number Elements */ public boolean expectedNodeCount(NodeList nodeList, int expected) { String tag; int length; if ((length = nodeList.getLength()) == expected) { return true; } tag = "Element"; if (length > 0) { tag = nodeList.item(0).getNodeName(); } _log.debug("Unexpected " + tag + " count: " + length + " (ignoring entry)"); return false; } /** * Locate select attribute of the first matching image * @param parent Parent element (look here for IMG tag) * @param name Attribute name (src, alt, etc) * @return Image name value (null if none) */ public String getImageAttribute(Element parent, String name) { Element image; String value; if ((image = DomUtils.getElement(parent, "IMG")) == null) { return null; } value = image.getAttribute(name); return StringUtils.isNull(value) ? null : value; } }