Java tutorial
/** * Licensed to the Sakai Foundation (SF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The SF licenses this file * to you 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. */ package org.sakaiproject.nakamura.docproxy.url; import com.ctc.wstx.stax.WstxInputFactory; import java.io.IOException; import java.io.InputStream; import java.security.SignatureException; import java.util.ArrayList; import java.util.Dictionary; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Map.Entry; import javax.jcr.Node; import javax.jcr.RepositoryException; import javax.xml.namespace.QName; import javax.xml.stream.XMLEventReader; import javax.xml.stream.XMLInputFactory; import javax.xml.stream.XMLStreamException; import javax.xml.stream.events.Attribute; import javax.xml.stream.events.Characters; import javax.xml.stream.events.StartElement; import javax.xml.stream.events.XMLEvent; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpMethod; import org.apache.commons.httpclient.methods.DeleteMethod; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.InputStreamRequestEntity; import org.apache.commons.httpclient.methods.PostMethod; import org.apache.felix.scr.annotations.Activate; import org.apache.felix.scr.annotations.Property; import org.apache.sling.commons.osgi.PropertiesUtil; import org.osgi.service.component.ComponentContext; import org.sakaiproject.nakamura.api.docproxy.DocProxyException; import org.sakaiproject.nakamura.api.docproxy.ExternalDocumentResult; import org.sakaiproject.nakamura.api.docproxy.ExternalDocumentResultMetadata; import org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor; import org.sakaiproject.nakamura.api.docproxy.ExternalSearchResultSet; import org.sakaiproject.nakamura.docproxy.ExternalSearchResultSetImpl; import org.sakaiproject.nakamura.util.Signature; /** * URL based document repository interactions. * */ public class UrlRepositoryProcessor implements ExternalRepositoryProcessor { public static final String TYPE = "url"; public static final String DEFAULT_HMAC_HEADER = "X-HMAC"; @Property(value = DEFAULT_HMAC_HEADER) static final String HMAC_HEADER = "hmac.header"; private String hmacHeader; @Property static final String SHARED_KEY = "shared.key"; private String sharedKey; public static final String DEFAULT_SEARCH_URL = "http://localhost/search/"; @Property(value = DEFAULT_SEARCH_URL) static final String SEARCH_URL = "search.url"; private String searchUrl; public static final String DEFAULT_DOCUMENT_URL = "http://localhost/doc?p="; @Property(value = DEFAULT_DOCUMENT_URL) static final String DOCUMENT_URL = "document.url"; private String documentUrl; public static final String DEFAULT_METADATA_URL = "http://localhost/metadata?p="; @Property(value = DEFAULT_METADATA_URL) static final String METADATA_URL = "metadata.url"; private String metadataUrl; public static final String DEFAULT_UPDATE_URL = "http://localhost/update?p="; @Property(value = DEFAULT_UPDATE_URL) static final String UPDATE_URL = "update.url"; private String updateUrl; public static final String DEFAULT_REMOVE_URL = "http://localhost/doc?p="; @Property(value = DEFAULT_REMOVE_URL) protected static final String REMOVE_URL = "remove.url"; private String removeUrl; private XMLInputFactory xmlInputFactory; private HttpClient client; /** * Default constructor. Used by OSGi. */ public UrlRepositoryProcessor() { client = new HttpClient(); } @Activate protected void activate(ComponentContext context) { xmlInputFactory = new WstxInputFactory(); xmlInputFactory.setProperty(XMLInputFactory.IS_COALESCING, true); xmlInputFactory.setProperty(XMLInputFactory.IS_VALIDATING, false); xmlInputFactory.setProperty(XMLInputFactory.IS_NAMESPACE_AWARE, true); // process properties into http methods Dictionary<?, ?> props = context.getProperties(); hmacHeader = PropertiesUtil.toString(props.get(HMAC_HEADER), DEFAULT_HMAC_HEADER); searchUrl = PropertiesUtil.toString(props.get(SEARCH_URL), DEFAULT_SEARCH_URL); documentUrl = PropertiesUtil.toString(props.get(DOCUMENT_URL), DEFAULT_DOCUMENT_URL); updateUrl = PropertiesUtil.toString(props.get(UPDATE_URL), DEFAULT_UPDATE_URL); metadataUrl = PropertiesUtil.toString(props.get(METADATA_URL), DEFAULT_METADATA_URL); removeUrl = PropertiesUtil.toString(props.get(REMOVE_URL), DEFAULT_REMOVE_URL); hmacHeader = PropertiesUtil.toString(props.get(HMAC_HEADER), DEFAULT_HMAC_HEADER); sharedKey = PropertiesUtil.toString(props.get(SHARED_KEY), null); } /* * (non-Javadoc) * * @see org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor#getType() */ public String getType() { return UrlRepositoryProcessor.TYPE; } /* * (non-Javadoc) * * @see * org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor#updateDocument * (javax.jcr.Node, java.lang.String, java.util.Map, java.io.InputStream, long) */ public Map<String, Object> updateDocument(Node node, String path, Map<String, Object> properties, InputStream documentStream, long streamLength) throws DocProxyException { PostMethod method = new PostMethod(updateUrl + path); for (Entry<String, Object> entry : properties.entrySet()) { method.addParameter(entry.getKey(), entry.getValue().toString()); } method.setRequestEntity(new InputStreamRequestEntity(documentStream)); executeMethod(method, node); return null; } /* * (non-Javadoc) * * @see * org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor#getDocument(javax * .jcr.Node, java.lang.String) */ public ExternalDocumentResult getDocument(Node node, String path) throws DocProxyException { try { GetMethod method = new GetMethod(documentUrl + path); executeMethod(method, node); ExternalDocumentResult result = parseDocument(method.getResponseBodyAsStream()); return result; } catch (XMLStreamException e) { throw new DocProxyException(500, e.getMessage()); } catch (IOException e) { throw new DocProxyException(500, e.getMessage()); } } /* * (non-Javadoc) * * @see * org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor#getDocumentMetadata * (javax.jcr.Node, java.lang.String) */ public ExternalDocumentResultMetadata getDocumentMetadata(Node node, String path) throws DocProxyException { try { GetMethod method = new GetMethod(metadataUrl + path); executeMethod(method, node); ExternalDocumentResultMetadata result = parseDocument(method.getResponseBodyAsStream()); return result; } catch (IOException e) { throw new DocProxyException(500, e.getMessage()); } catch (XMLStreamException e) { throw new DocProxyException(500, e.getMessage()); } } /* * (non-Javadoc) * * @see * org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor#search(javax.jcr * .Node, java.util.Map) */ public ExternalSearchResultSet search(Node node, Map<String, Object> searchProperties) throws DocProxyException { try { PostMethod method = new PostMethod(searchUrl); for (Entry<String, Object> entry : searchProperties.entrySet()) { method.addParameter(entry.getKey(), entry.getValue().toString()); } executeMethod(method, node); List<ExternalDocumentResult> results = parseSearch(method.getResponseBodyAsStream()); ExternalSearchResultSet resultSet = new ExternalSearchResultSetImpl(results.iterator(), (long) results.size()); return resultSet; } catch (XMLStreamException e) { throw new DocProxyException(500, e.getMessage()); } catch (IOException e) { throw new DocProxyException(500, e.getMessage()); } } /* * (non-Javadoc) * * @see * org.sakaiproject.nakamura.api.docproxy.ExternalRepositoryProcessor#removeDocument * (javax.jcr.Node, java.lang.String) */ public void removeDocument(Node node, String path) throws DocProxyException { DeleteMethod method = new DeleteMethod(removeUrl + path); executeMethod(method, node); } /** * Execute an http method and return the status code. * * @param method * @return * @throws IOException * @throws DocProxyException */ private int executeMethod(HttpMethod method, Node node) throws DocProxyException { try { addHmac(method, node); int returnCode = client.executeMethod(method); if (returnCode < 200 || returnCode >= 300) { throw new DocProxyException(returnCode, "Error occurred while executing method [" + method.getName() + ":" + returnCode + "]"); } return returnCode; } catch (IOException e) { throw new DocProxyException(500, e.getMessage()); } catch (RepositoryException e) { throw new DocProxyException(500, e.getMessage()); } catch (SignatureException e) { throw new DocProxyException(500, e.getMessage()); } } /** * Parse search results information into documents. * <p> * The expected format of the returned information is:<br/> * <code> * <documents> * <document contentLength="%s" contentType="%s" uri="%s"> * <properties> * <key1>value1</key1> * <key2>value2</key2> * </properties> * </document> * </documents> * </code> * </p> * * @param body * @return * @throws JSONException */ protected List<ExternalDocumentResult> parseSearch(InputStream body) throws XMLStreamException { ArrayList<ExternalDocumentResult> results = new ArrayList<ExternalDocumentResult>(); XMLEventReader eventReader = xmlInputFactory.createXMLEventReader(body); while (eventReader.hasNext()) { XMLEvent event = eventReader.nextEvent(); // process the event if we're starting an element if (event.isStartElement()) { StartElement startEl = event.asStartElement(); QName startElName = startEl.getName(); String startElLocalName = startElName.getLocalPart(); // process the href element if ("document".equalsIgnoreCase(startElLocalName)) { results.add(parseDocument(startEl, null)); event = eventReader.nextEvent(); continue; } } } return results; } /** * Parse information about a doc from JSON to an {@link ExternalDocumentResult} object.<br/> * XML is expected to follow the format of: * <p> * <code> * <document contentLength="%s" contentType="%s" uri="%s"> * <properties> * <key1>value1</key1> * <key2>value2</key2> * </properties> * </document> * </code> * </p> * * @param is * @return * @throws ParserConfigurationException * @throws IOException * @throws SAXException */ protected ExternalDocumentResult parseDocument(InputStream body) throws XMLStreamException { UrlDocumentResult doc = new UrlDocumentResult(); XMLEventReader eventReader = xmlInputFactory.createXMLEventReader(body); while (eventReader.hasNext()) { XMLEvent event = eventReader.nextEvent(); // process the event if we're starting an element if (event.isStartElement()) { StartElement startEl = event.asStartElement(); QName startElName = startEl.getName(); String startElLocalName = startElName.getLocalPart(); if ("document".equalsIgnoreCase(startElLocalName)) { parseDocument(startEl, doc); continue; } if ("properties".equalsIgnoreCase(startElLocalName)) { parseProperties(eventReader, doc); continue; } } } return doc; } /** * Parse the attributes of an XML 'document' element into a {@link UrlDocumentResult}. * * @param startEl * The 'document' element to process. * @param doc * The document to set attributes into. If null, a new * {@link UrlDocumentResult} is created. * @return A {@link UrlDocumentResult} containing values found in {@link startEl}. This * will be the provided doc, if it is not null, or a newly created one. * @throws XMLStreamException * If there is a problem processing the element. */ private UrlDocumentResult parseDocument(StartElement startEl, UrlDocumentResult doc) throws XMLStreamException { UrlDocumentResult _doc = null; if (doc != null) { _doc = doc; } else { _doc = new UrlDocumentResult(); } @SuppressWarnings("unchecked") Iterator<Attribute> attrs = startEl.getAttributes(); while (attrs.hasNext()) { Attribute attr = attrs.next(); QName attrName = attr.getName(); String attrLocalName = attrName.getLocalPart(); // collect the uri if ("uri".equalsIgnoreCase(attrLocalName)) { _doc.setUri(attr.getValue()); continue; } // collect the content length if ("contentLength".equalsIgnoreCase(attrLocalName)) { _doc.setContentLength(Long.parseLong(attr.getValue())); continue; } // collect the content length if ("contentType".equalsIgnoreCase(attrLocalName)) { _doc.setContentType(attr.getValue()); continue; } } return _doc; } /** * Parse subelements of a 'properties' element into properties on a * {@link UrlDocumentResult}. * * @param eventReader * Source to process elements from. Is expected that calls to * eventReader.nextEvent() will yield elements to be added to doc as * properties. Nested elements are not considered. * @param doc * The document to set attributes into. * @throws XMLStreamException * If there is a problem processing the element. */ private void parseProperties(XMLEventReader eventReader, UrlDocumentResult doc) throws XMLStreamException { while (eventReader.hasNext()) { XMLEvent event = eventReader.nextEvent(); // process the event if we're starting an element if (event.isStartElement()) { StartElement startEl = event.asStartElement(); QName startElName = startEl.getName(); String startElLocalName = startElName.getLocalPart(); // collect simple elements as properties event = eventReader.nextEvent(); if (event.isCharacters()) { Characters chars = event.asCharacters(); doc.addProperty(startElLocalName, chars.getData()); } } } } /** * Adds an HMAC header with the current user Id attached. * * @param method * @param node * @throws RepositoryException * @throws SignatureException */ private void addHmac(HttpMethod method, Node node) throws RepositoryException, SignatureException { String currentUserId = node.getSession().getUserID(); String hmac = Signature.calculateRFC2104HMAC(currentUserId, sharedKey); String hmacHeaderValue = hmac + ";" + currentUserId; method.addRequestHeader(hmacHeader, hmacHeaderValue); } }