Java tutorial
/* The contents of this file are subject to the license and copyright terms * detailed in the license directory at the root of the source tree (also * available online at http://fedora-commons.org/license/). */ package fedora.server.storage; import java.io.File; import java.net.URI; import java.net.URL; import java.util.Hashtable; import java.util.Map; import javax.activation.MimetypesFileTypeMap; import org.apache.commons.httpclient.Header; import org.apache.log4j.Logger; import fedora.common.http.HttpInputStream; import fedora.common.http.WebClient; import fedora.server.Context; import fedora.server.Module; import fedora.server.ReadOnlyContext; import fedora.server.Server; import fedora.server.errors.GeneralException; import fedora.server.errors.HttpServiceNotFoundException; import fedora.server.errors.ModuleInitializationException; import fedora.server.errors.authorization.AuthzException; import fedora.server.security.Authorization; import fedora.server.security.BackendPolicies; import fedora.server.security.BackendSecurity; import fedora.server.security.BackendSecuritySpec; import fedora.server.storage.types.MIMETypedStream; import fedora.server.storage.types.Property; import fedora.server.utilities.ServerUtility; /** * Provides a mechanism to obtain external HTTP-accessible content. * * @author Ross Wayland * @version $Id$ * */ public class DefaultExternalContentManager extends Module implements ExternalContentManager { /** Logger for this class. */ private static final Logger LOG = Logger.getLogger(DefaultExternalContentManager.class.getName()); private static final String DEFAULT_MIMETYPE = "text/plain"; private String m_userAgent; private String fedoraServerHost; private String fedoraServerPort; private String fedoraServerRedirectPort; private WebClient m_http; /** * Creates a new DefaultExternalContentManager. * * @param moduleParameters * The name/value pair map of module parameters. * @param server * The server instance. * @param role * The module role name. * @throws ModuleInitializationException * If initialization values are invalid or initialization fails for * some other reason. */ public DefaultExternalContentManager(Map<String, String> moduleParameters, Server server, String role) throws ModuleInitializationException { super(moduleParameters, server, role); } /** * Initializes the Module based on configuration parameters. The * implementation of this method is dependent on the schema used to define * the parameter names for the role of * <code>fedora.server.storage.DefaultExternalContentManager</code>. * * @throws ModuleInitializationException * If initialization values are invalid or initialization fails for * some other reason. */ @Override public void initModule() throws ModuleInitializationException { try { Server s_server = getServer(); m_userAgent = getParameter("userAgent"); if (m_userAgent == null) { m_userAgent = "Fedora"; } fedoraServerPort = s_server.getParameter("fedoraServerPort"); fedoraServerHost = s_server.getParameter("fedoraServerHost"); fedoraServerRedirectPort = s_server.getParameter("fedoraRedirectPort"); m_http = new WebClient(); m_http.USER_AGENT = m_userAgent; } catch (Throwable th) { throw new ModuleInitializationException("[DefaultExternalContentManager] " + "An external content manager " + "could not be instantiated. The underlying error was a " + th.getClass().getName() + "The message was \"" + th.getMessage() + "\".", getRole()); } } /* * Retrieves the external content. * Currently the protocols <code>file</code> and * <code>http[s]</code> are supported. * * @see * fedora.server.storage.ExternalContentManager#getExternalContent(fedora * .server.storage.ContentManagerParams) */ public MIMETypedStream getExternalContent(ContentManagerParams params) throws GeneralException, HttpServiceNotFoundException { LOG.debug("in getExternalContent(), url=" + params.getUrl()); try { if (params.getProtocol().equals("file")) { return getFromFilesystem(params); } if (params.getProtocol().equals("http") || params.getProtocol().equals("https")) { return getFromWeb(params); } throw new GeneralException( "protocol for retrieval of external content not supported. URL: " + params.getUrl()); } catch (Exception ex) { // catch anything but generalexception ex.printStackTrace(); throw new HttpServiceNotFoundException( "[" + this.getClass().getSimpleName() + "] " + "returned an error. The underlying error was a " + ex.getClass().getName() + " The message " + "was \"" + ex.getMessage() + "\" . ", ex); } } /** * Get a MIMETypedStream for the given URL. If user or password are * <code>null</code>, basic authentication will not be attempted. */ private MIMETypedStream get(String url, String user, String pass, String knownMimeType) throws GeneralException { LOG.debug("DefaultExternalContentManager.get(" + url + ")"); try { HttpInputStream response = m_http.get(url, true, user, pass); String mimeType = response.getResponseHeaderValue("Content-Type", knownMimeType); Property[] headerArray = toPropertyArray(response.getResponseHeaders()); return new MIMETypedStream(mimeType, response, headerArray); } catch (Exception e) { throw new GeneralException("Error getting " + url, e); } } /** * Convert the given HTTP <code>Headers</code> to an array of * <code>Property</code> objects. */ private static Property[] toPropertyArray(Header[] headers) { Property[] props = new Property[headers.length]; for (int i = 0; i < headers.length; i++) { props[i] = new Property(); props[i].name = headers[i].getName(); props[i].value = headers[i].getValue(); } return props; } /** * Creates a property array out of the MIME type and the length of the * provided file. * * @param file * the file containing the content. * @return an array of properties containing content-length and * content-type. */ private static Property[] getPropertyArray(File file, String mimeType) { Property[] props = new Property[2]; Property clen = new Property("Content-Length", Long.toString(file.length())); Property ctype = new Property("Content-Type", mimeType); props[0] = clen; props[1] = ctype; return props; } /** * Get a MIMETypedStream for the given URL. If user or password are * <code>null</code>, basic authentication will not be attempted. * * @param params * @return * @throws HttpServiceNotFoundException * @throws GeneralException */ private MIMETypedStream getFromFilesystem(ContentManagerParams params) throws HttpServiceNotFoundException, GeneralException { LOG.debug("in getFile(), url=" + params.getUrl()); try { URL fileUrl = new URL(params.getUrl()); File cFile = new File(fileUrl.toURI()).getCanonicalFile(); // security check URI cURI = cFile.toURI(); LOG.info("Checking resolution security on " + cURI); Authorization authModule = (Authorization) getServer() .getModule("fedora.server.security.Authorization"); if (authModule == null) { throw new GeneralException("Missing required Authorization module"); } authModule.enforceRetrieveFile(params.getContext(), cURI.toString()); // end security check String mimeType = params.getMimeType(); // if mimeType was not given, try to determine it automatically if (mimeType == null || mimeType.equalsIgnoreCase("")) { mimeType = determineMimeType(cFile); } return new MIMETypedStream(mimeType, fileUrl.openStream(), getPropertyArray(cFile, mimeType)); } catch (AuthzException ae) { LOG.error(ae.getMessage(), ae); throw new HttpServiceNotFoundException("Policy blocked datastream resolution", ae); } catch (GeneralException me) { LOG.error(me.getMessage(), me); throw me; } catch (Throwable th) { th.printStackTrace(System.err); // catch anything but generalexception LOG.error(th.getMessage(), th); throw new HttpServiceNotFoundException( "[FileExternalContentManager] " + "returned an error. The underlying error was a " + th.getClass().getName() + " The message " + "was \"" + th.getMessage() + "\" . ", th); } } /** * Retrieves external content via http or https. * * @param url * The url pointing to the content. * @param context * The Map containing parameters. * @param mimeType * The default MIME type to be used in case no MIME type can be * detected. * @return A MIMETypedStream * @throws ModuleInitializationException * @throws GeneralException */ private MIMETypedStream getFromWeb(ContentManagerParams params) throws ModuleInitializationException, GeneralException { String username = params.getUsername(); String password = params.getPassword(); boolean backendSSL = false; String url = params.getUrl(); if (ServerUtility.isURLFedoraServer(url) && !params.isBypassBackend()) { BackendSecuritySpec m_beSS; BackendSecurity m_beSecurity = (BackendSecurity) getServer() .getModule("fedora.server.security.BackendSecurity"); try { m_beSS = m_beSecurity.getBackendSecuritySpec(); } catch (Exception e) { throw new ModuleInitializationException( "Can't intitialize BackendSecurity module (in default access) from Server.getModule", getRole()); } Hashtable<String, String> beHash = m_beSS.getSecuritySpec(BackendPolicies.FEDORA_INTERNAL_CALL); username = (String) beHash.get("callUsername"); password = (String) beHash.get("callPassword"); backendSSL = new Boolean((String) beHash.get("callSSL")).booleanValue(); if (backendSSL) { if (params.getProtocol().equals("http:")) { url = url.replaceFirst("http:", "https:"); } url = url.replaceFirst(":" + fedoraServerPort + "/", ":" + fedoraServerRedirectPort + "/"); } if (LOG.isDebugEnabled()) { LOG.debug("************************* backendUsername: " + username + " backendPassword: " + password + " backendSSL: " + backendSSL); LOG.debug("************************* doAuthnGetURL: " + url); } } return get(url, username, password, params.getMimeType()); } /** * Determines the mime type of a given file * * @param file for which the mime type needs to be detected * @return the detected mime type */ private String determineMimeType(File file) { String mimeType = new MimetypesFileTypeMap().getContentType(file); // if mimeType detection failed, fall back to the default if (mimeType == null || mimeType.equalsIgnoreCase("")) { mimeType = DEFAULT_MIMETYPE; } return mimeType; } }