Java tutorial
/** * The contents of this file are subject to the license and copyright * detailed in the LICENSE and NOTICE files at the root of the source * tree and available online at * * http://www.dspace.org/license/ */ package org.dspace.license; import java.io.IOException; import java.io.OutputStreamWriter; import java.io.UnsupportedEncodingException; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; import java.net.URLEncoder; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.NoSuchElementException; import org.apache.commons.lang.StringUtils; import org.apache.log4j.Logger; import org.jaxen.JaxenException; import org.jaxen.jdom.JDOMXPath; import org.jdom.Attribute; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; import org.jdom.output.XMLOutputter; import org.dspace.core.ConfigurationManager; /** * A wrapper around Creative Commons REST web services. * * @author Wendy Bossons */ public class CCLookup { /** log4j logger */ private static Logger log = Logger.getLogger(CCLookup.class); private static String cc_root = ConfigurationManager.getProperty("cc.api.rooturl"); private static String jurisdiction; private static List<String> lcFilter = new ArrayList<String>(); private Document license_doc = null; private String rdfString = null; private String errorMessage = null; private boolean success = false; private SAXBuilder parser = new SAXBuilder(); private List<CCLicense> licenses = new ArrayList<CCLicense>(); private List<CCLicenseField> licenseFields = new ArrayList<CCLicenseField>(); static { // if defined, set a proxy server for http requests to Creative // Commons site String proxyHost = ConfigurationManager.getProperty("http.proxy.host"); String proxyPort = ConfigurationManager.getProperty("http.proxy.port"); if (StringUtils.isNotBlank(proxyHost) && StringUtils.isNotBlank(proxyPort)) { System.setProperty("http.proxyHost", proxyHost); System.setProperty("http.proxyPort", proxyPort); } String jurisProp = ConfigurationManager.getProperty("cc.license.jurisdiction"); jurisdiction = (jurisProp != null) ? jurisProp : ""; String filterList = ConfigurationManager.getProperty("cc.license.classfilter"); if (filterList != null) { for (String name : filterList.split(",")) { lcFilter.add(name.trim()); } } } /** * Constructs a new instance with the default web services root. * */ public CCLookup() { super(); } /** * Returns the id for a particular CCLicense label. Returns an * empty string if no match is found. * * @param class_label The CCLicense label to find. * @return Returns a String containing the License class ID if the label * is found; if not found, returns an empty string. * * @see CCLicense * */ public String getLicenseId(String class_label) { for (int i = 0; i < this.licenses.size(); i++) { if (((CCLicense) this.licenses.get(i)).getLicenseName().equals(class_label)) { return ((CCLicense) this.licenses.get(i)).getLicenseId(); } } return ""; } /** * Queries the web service for the available licenses. * * @param language The language to request labels and description strings in. * @return Returns a Map of CCLicense objects. * * @see Map * @see CCLicense * */ public Collection<CCLicense> getLicenses(String language) { // create XPath expressions try { JDOMXPath xp_Licenses = new JDOMXPath("//licenses/license"); JDOMXPath xp_LicenseID = new JDOMXPath("@id"); URL classUrl = new URL(this.cc_root + "/?locale=" + language); Document classDoc = this.parser.build(classUrl); // extract the identifiers and labels using XPath List<Element> results = xp_Licenses.selectNodes(classDoc); // populate licenses container this.licenses.clear(); for (int i = 0; i < results.size(); i++) { Element license = results.get(i); // add if not filtered String liD = ((Attribute) xp_LicenseID.selectSingleNode(license)).getValue(); if (!lcFilter.contains(liD)) { this.licenses.add(new CCLicense(liD, license.getText(), i)); } } } catch (JaxenException jaxen_e) { return null; } catch (JDOMException jdom_e) { return null; } catch (IOException io_e) { return null; } catch (Exception e) { // do nothing... but we should return null; } return licenses; } /** * Queries the web service for a set of licenseFields for a particular license class. * * @param license A String specifying the CCLicense identifier to * retrieve fields for. * @return A Collection of LicenseField objects. * * @see CCLicense * */ public Collection<CCLicenseField> getLicenseFields(String license, String language) { JDOMXPath xp_LicenseField; JDOMXPath xp_LicenseID; JDOMXPath xp_FieldType; JDOMXPath xp_Description; JDOMXPath xp_Label; JDOMXPath xp_Enum; Document fieldDoc; URL classUrl; List results = null; List enumOptions = null; // create XPath expressions try { xp_LicenseField = new JDOMXPath("//field"); xp_LicenseID = new JDOMXPath("@id"); xp_Description = new JDOMXPath("description"); xp_Label = new JDOMXPath("label"); xp_FieldType = new JDOMXPath("type"); xp_Enum = new JDOMXPath("enum"); } catch (JaxenException e) { return null; } // retrieve and parse the license class document try { classUrl = new URL(this.cc_root + "/license/" + license + "?locale=" + language); } catch (Exception err) { // do nothing... but we should return null; } // parse the licenses document try { fieldDoc = this.parser.build(classUrl); } catch (JDOMException e) { return null; } catch (IOException e) { return null; } // reset the field definition container this.licenseFields.clear(); // extract the identifiers and labels using XPath try { results = xp_LicenseField.selectNodes(fieldDoc); } catch (JaxenException e) { return null; } for (int i = 0; i < results.size(); i++) { Element field = (Element) results.get(i); try { // create the field object CCLicenseField cclicensefield = new CCLicenseField( ((Attribute) xp_LicenseID.selectSingleNode(field)).getValue(), ((Element) xp_Label.selectSingleNode(field)).getText()); // extract additional properties cclicensefield.setDescription(((Element) xp_Description.selectSingleNode(field)).getText()); cclicensefield.setType(((Element) xp_FieldType.selectSingleNode(field)).getText()); enumOptions = xp_Enum.selectNodes(field); for (int j = 0; j < enumOptions.size(); j++) { String id = ((Attribute) xp_LicenseID.selectSingleNode(enumOptions.get(j))).getValue(); String label = ((Element) xp_Label.selectSingleNode(enumOptions.get(j))).getText(); cclicensefield.getEnum().put(id, label); } // for each enum option this.licenseFields.add(cclicensefield); } catch (JaxenException e) { return null; } } return licenseFields; } // licenseFields /** * Passes a set of "answers" to the web service and retrieves a license. * * @param licenseId The identifier of the license class being requested. * @param answers A Map containing the answers to the license fields; * each key is the identifier of a LicenseField, with the value * containing the user-supplied answer. * @param lang The language to request localized elements in. * * @throws IOException * * @see CCLicense * @see Map */ public void issue(String licenseId, Map answers, String lang) throws IOException { // Determine the issue URL String issueUrl = this.cc_root + "/license/" + licenseId + "/issue"; // Assemble the "answers" document String answer_doc = "<answers>\n<locale>" + lang + "</locale>\n" + "<license-" + licenseId + ">\n"; Iterator keys = answers.keySet().iterator(); try { String current = (String) keys.next(); while (true) { answer_doc += "<" + current + ">" + (String) answers.get(current) + "</" + current + ">\n"; current = (String) keys.next(); } } catch (NoSuchElementException e) { // exception indicates we've iterated through the // entire collection; just swallow and continue } // answer_doc += "<jurisdiction></jurisidiction>\n"; FAILS with jurisdiction argument answer_doc += "</license-" + licenseId + ">\n</answers>\n"; String post_data; try { post_data = URLEncoder.encode("answers", "UTF-8") + "=" + URLEncoder.encode(answer_doc, "UTF-8"); } catch (UnsupportedEncodingException e) { return; } URL post_url; try { post_url = new URL(issueUrl); } catch (MalformedURLException e) { return; } URLConnection connection = post_url.openConnection(); // this will not be needed after I'm done TODO: remove connection.setDoOutput(true); OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream()); writer.write(post_data); writer.flush(); // end TODO try { // parsing document from input stream java.io.InputStream stream = connection.getInputStream(); this.license_doc = this.parser.build(stream); } catch (JDOMException jde) { log.warn(jde.getMessage()); } catch (Exception e) { log.warn(e.getCause()); } return; } // issue /** * Passes a set of "answers" to the web service and retrieves a license. * * @param licenseURI The uri of the license. * * Note: does not support localization in 1.5 -- not yet * * @throws IOException * * @see CCLicense * @see Map */ public void issue(String licenseURI) throws IOException { // Determine the issue URL // Example: http://api.creativecommons.org/rest/1.5/details? // license-uri=http://creativecommons.org/licenses/by-nc-sa/3.0/ String issueUrl = cc_root + "/details?license-uri=" + licenseURI; URL request_url; try { request_url = new URL(issueUrl); } catch (MalformedURLException e) { return; } URLConnection connection = request_url.openConnection(); // this will not be needed after I'm done TODO: remove connection.setDoOutput(true); try { // parsing document from input stream java.io.InputStream stream = connection.getInputStream(); license_doc = this.parser.build(stream); } catch (JDOMException jde) { log.warn(jde.getMessage()); } catch (Exception e) { log.warn(e.getCause()); } return; } // issue /** * Retrieves the URI for the license issued. * * @return A String containing the URI for the license issued. */ public String getLicenseUrl() { String text = null; try { JDOMXPath xp_LicenseName = new JDOMXPath("//result/license-uri"); text = ((Element) xp_LicenseName.selectSingleNode(this.license_doc)).getText(); } catch (Exception e) { log.warn(e.getMessage()); setSuccess(false); text = "An error occurred getting the license - uri."; } finally { return text; } } // getLicenseUrl /** * Retrieves the human readable name for the license issued. * * @return A String containing the license name. */ public String getLicenseName() { String text = null; try { JDOMXPath xp_LicenseName = new JDOMXPath("//result/license-name"); text = ((Element) xp_LicenseName.selectSingleNode(this.license_doc)).getText(); } catch (Exception e) { log.warn(e.getMessage()); setSuccess(false); text = "An error occurred on the license name."; } finally { return text; } } // getLicenseName public org.jdom.Document getLicenseDocument() { return this.license_doc; } public String getRdf() throws IOException { String myString = null; java.io.ByteArrayOutputStream outputstream = new java.io.ByteArrayOutputStream(); try { outputstream.write("<result>\n".getBytes()); JDOMXPath xpathRdf = new JDOMXPath("//result/rdf"); JDOMXPath xpathLicenseRdf = new JDOMXPath("//result/licenserdf"); XMLOutputter xmloutputter = new XMLOutputter(); Element rdfParent = ((Element) xpathRdf.selectSingleNode(this.license_doc)); xmloutputter.output(rdfParent, outputstream); Element licenseRdfParent = ((Element) xpathLicenseRdf.selectSingleNode(this.license_doc)); outputstream.write("\n".getBytes()); xmloutputter.output(licenseRdfParent, outputstream); outputstream.write("\n</result>\n".getBytes()); } catch (Exception e) { log.warn("An error occurred getting the rdf . . ." + e.getMessage()); setSuccess(false); } finally { outputstream.close(); return outputstream.toString(); } } public boolean isSuccess() { setSuccess(false); JDOMXPath xp_Success; String text = null; try { xp_Success = new JDOMXPath("//message"); text = ((Element) xp_Success.selectSingleNode(this.license_doc)).getText(); setErrorMessage(text); } catch (Exception e) { log.warn("There was an issue . . . " + text); setSuccess(true); } return this.success; } private void setSuccess(boolean success) { this.success = success; } public String getErrorMessage() { return this.errorMessage; } private void setErrorMessage(String errorMessage) { this.errorMessage = errorMessage; } }