Java tutorial
/* * Carrot2 project. * * Copyright (C) 2002-2010, Dawid Weiss, Stanisaw Osiski. * All rights reserved. * * Refer to the full license file "carrot2.LICENSE" * in the root folder of the repository checkout or at: * http://www.carrot2.org/carrot2.LICENSE */ package org.carrot2.source.xml; import java.io.*; import java.util.Map; import javax.xml.transform.*; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; import org.apache.commons.httpclient.HttpStatus; import org.carrot2.core.IDocumentSource; import org.carrot2.core.ProcessingResult; import org.carrot2.core.attribute.Processing; import org.carrot2.source.SearchEngineResponse; import org.carrot2.util.CloseableUtils; import org.carrot2.util.StreamUtils; import org.carrot2.util.attribute.Attribute; import org.carrot2.util.attribute.Bindable; import org.carrot2.util.attribute.Input; import org.carrot2.util.attribute.constraint.IntRange; import org.carrot2.util.httpclient.HttpUtils; import org.carrot2.util.resource.IResource; import org.carrot2.util.xslt.NopURIResolver; import org.carrot2.util.xslt.TemplatesPool; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.xml.sax.SAXException; /** * Exposes the common functionality a {@link IDocumentSource} based on XML/XSLT is likely * to need. This helper does note expose any attributes, so that different implementations * can decide which attributes they expose. */ @Bindable(prefix = "XmlDocumentSourceHelper") public class XmlDocumentSourceHelper { /** * Data transfer timeout. Specifies the data transfer timeout, in seconds. A timeout value of * zero is interpreted as an infinite timeout. * * @label Data transfer timeout * @level Advanced * @group Service */ @Input @Processing @Attribute @IntRange(min = 0, max = 5 * 60) public int timeout = 8; /** Precompiled XSLT templates. */ private final TemplatesPool pool; /** * URI resolver. Does nothing. */ private final static URIResolver uriResolver = new NopURIResolver(); private final static Logger log = LoggerFactory.getLogger(XmlDocumentSourceHelper.class); /** * */ public XmlDocumentSourceHelper() { try { // No template caching. this.pool = new TemplatesPool(false); this.pool.tFactory.setURIResolver(uriResolver); } catch (Exception e) { throw new RuntimeException(e); } } /** * Loads a {@link ProcessingResult} from the provided remote URL, applying XSLT * transform if specified. This method can handle gzip-compressed streams if supported * by the data source. * * @param metadata if a non-<code>null</code> map is provided, request metadata will * be put into the map. * @param user if not <code>null</code>, the user name to use for HTTP Basic * Authentication * @param password if not <code>null</code>, the password to use for HTTP Basic * Authentication */ public ProcessingResult loadProcessingResult(String url, Templates stylesheet, Map<String, String> xsltParameters, Map<String, Object> metadata, String user, String password) throws Exception { final HttpUtils.Response response = HttpUtils.doGET(url, null, null, user, password, timeout * 1000); final InputStream carrot2XmlStream = response.getPayloadAsStream(); final int statusCode = response.status; if (statusCode == HttpStatus.SC_OK) { metadata.put(SearchEngineResponse.COMPRESSION_KEY, response.compression); return loadProcessingResult(carrot2XmlStream, stylesheet, xsltParameters); } else { throw new IOException("HTTP error, status code: " + statusCode); } } /** * Loads a {@link ProcessingResult} from the provided {@link InputStream}, applying * XSLT transform if specified. The provided {@link InputStream} will be closed. */ public ProcessingResult loadProcessingResult(InputStream xml, Templates stylesheet, Map<String, String> xsltParameters) throws Exception { InputStream carrot2XmlStream = null; try { carrot2XmlStream = getCarrot2XmlStream(xml, stylesheet, xsltParameters); return ProcessingResult.deserialize(carrot2XmlStream); } finally { CloseableUtils.close(carrot2XmlStream, xml); } } /** * Returns a Carrot2 XML stream, applying an XSLT transformation if the stylesheet is * provided. */ private InputStream getCarrot2XmlStream(InputStream xmlInputStream, Templates stylesheet, Map<String, String> xsltParameters) throws TransformerConfigurationException, IOException, TransformerException { // Perform transformation if stylesheet found. InputStream carrot2XmlInputStream; if (stylesheet != null) { byte[] debugInput = null; try { // Initialize transformer final Transformer transformer = pool.newTransformer(stylesheet); final ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); // Set XSLT parameters, if any if (xsltParameters != null) { for (Map.Entry<String, String> entry : xsltParameters.entrySet()) { transformer.setParameter(entry.getKey(), entry.getValue()); } } if (log.isDebugEnabled()) { debugInput = StreamUtils.readFullyAndClose(xmlInputStream); xmlInputStream = new ByteArrayInputStream(debugInput); } // Perform transformation transformer.transform(new StreamSource(xmlInputStream), new StreamResult(outputStream)); carrot2XmlInputStream = new ByteArrayInputStream(outputStream.toByteArray()); } catch (TransformerException e) { if (debugInput != null) { log.debug("Transformer input: " + new String(debugInput, "UTF-8")); } throw e; } finally { CloseableUtils.close(xmlInputStream); } } else { carrot2XmlInputStream = xmlInputStream; } return carrot2XmlInputStream; } /** * Loads the XSLT stylesheet from the provided {@link IResource}. */ public Templates loadXslt(IResource xslt) { InputStream is = null; try { is = xslt.open(); return pool.compileTemplate(is); } catch (IOException e) { throw new RuntimeException(e); } catch (SAXException e) { throw new RuntimeException(e); } finally { CloseableUtils.close(is); } } }