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 org.fcrepo.server.rest; import java.io.File; import java.io.StringReader; import java.io.Writer; import java.net.URI; import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpServletRequest; import javax.ws.rs.WebApplicationException; import javax.ws.rs.core.HttpHeaders; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; import javax.ws.rs.core.Response.ResponseBuilder; import javax.ws.rs.core.Response.Status; import javax.ws.rs.core.UriInfo; import javax.xml.transform.Templates; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerConfigurationException; import javax.xml.transform.TransformerException; import javax.xml.transform.TransformerFactory; import javax.xml.transform.TransformerFactoryConfigurationError; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; import net.sf.saxon.FeatureKeys; import org.apache.commons.io.IOUtils; import org.codehaus.jackson.map.ObjectMapper; import org.fcrepo.common.Constants; import org.fcrepo.server.Context; import org.fcrepo.server.ReadOnlyContext; import org.fcrepo.server.Server; import org.fcrepo.server.access.Access; import org.fcrepo.server.errors.DatastreamLockedException; import org.fcrepo.server.errors.DatastreamNotFoundException; import org.fcrepo.server.errors.ObjectLockedException; import org.fcrepo.server.errors.ObjectNotInLowlevelStorageException; import org.fcrepo.server.errors.ObjectValidityException; import org.fcrepo.server.errors.authorization.AuthzException; import org.fcrepo.server.management.Management; import org.fcrepo.server.storage.types.MIMETypedStream; import org.fcrepo.server.storage.types.Property; import org.fcrepo.server.utilities.TimestampedCacheEntry; import org.fcrepo.utilities.XmlTransformUtility; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * A barebone RESTFUL resource implementation. * * @author cuong.tran@yourmediashelf.com * @version $Id$ */ public class BaseRestResource { public static final String VALID_PID_PART = "/{pid : ([A-Za-z0-9]|-|\\.)+(:|%3A|%3a)(([A-Za-z0-9])|-|\\.|~|_|(%[0-9A-F]{2}))+}"; private static final Logger LOGGER = LoggerFactory.getLogger(BaseRestResource.class); static final String[] EMPTY_STRING_ARRAY = new String[0]; static final String DEFAULT_ENC = "UTF-8"; public static final String FORM = "multipart/form-data"; public static final String HTML = "text/html"; public static final String XML = "text/xml"; public static final String ZIP = "application/zip"; public static final MediaType TEXT_HTML = new MediaType("text", "html"); public static final MediaType TEXT_XML = new MediaType("text", "xml"); public static final MediaType APP_ZIP = new MediaType("application", "zip"); protected Server m_server; protected Management m_management; protected Access m_access; protected String m_hostname; protected ObjectMapper m_mapper; protected Map<String, TimestampedCacheEntry<Templates>> m_templates = new HashMap<String, TimestampedCacheEntry<Templates>>( 1); protected DatastreamFilenameHelper m_datastreamFilenameHelper; @javax.ws.rs.core.Context protected HttpServletRequest m_servletRequest; @javax.ws.rs.core.Context protected UriInfo m_uriInfo; @javax.ws.rs.core.Context protected HttpHeaders m_headers; public BaseRestResource(Server server) { try { this.m_server = server; this.m_management = (Management) m_server.getModule("org.fcrepo.server.management.Management"); this.m_access = (Access) m_server.getModule("org.fcrepo.server.access.Access"); this.m_hostname = m_server.getParameter("fedoraServerHost"); m_datastreamFilenameHelper = new DatastreamFilenameHelper(m_server, m_management, m_access); m_mapper = new ObjectMapper(); } catch (Exception ex) { throw new RestException("Unable to locate Fedora server instance", ex); } } protected Context getContext() { return ReadOnlyContext.getContext(Constants.HTTP_REQUEST.REST.uri, m_servletRequest); } protected DefaultSerializer getSerializer(Context context) { return new DefaultSerializer(m_hostname, context); } protected void transform(String xml, String xslt, Writer out) throws TransformerFactoryConfigurationError, TransformerConfigurationException, TransformerException { File xslFile = new File(m_server.getHomeDir(), xslt); TimestampedCacheEntry<Templates> entry = m_templates.get(xslt); if (entry == null || entry.timestamp() < xslFile.lastModified()) { Templates template = XmlTransformUtility.getTemplates(xslFile); entry = new TimestampedCacheEntry<Templates>(xslFile.lastModified(), template); m_templates.put(xslt, entry); } Transformer transformer = entry.value().newTransformer(); String appContext = getContext().getEnvironmentValue(Constants.FEDORA_APP_CONTEXT_NAME); transformer.setParameter("fedora", appContext); transformer.transform(new StreamSource(new StringReader(xml)), new StreamResult(out)); } protected Response buildResponse(MIMETypedStream result) throws Exception { if (result.MIMEType.equalsIgnoreCase("application/fedora-redirect")) { URI location = URI.create(IOUtils.toString(result.getStream())); return Response.temporaryRedirect(location).build(); } else { ResponseBuilder builder = Response.ok(); if (result.header != null) { for (Property header : result.header) { if (header.name != null && !(header.name.equalsIgnoreCase("transfer-encoding")) && !(header.name.equalsIgnoreCase("content-length")) && !(header.name.equalsIgnoreCase("content-type"))) { builder.header(header.name, header.value); } } } if (result.getSize() != -1L) { builder.header("content-length", result.getSize()); } if (!result.MIMEType.equals("")) { builder.type(result.MIMEType); } builder.entity(result.getStream()); return builder.build(); } } private Response handleException(Exception ex) { if (ex instanceof ObjectNotInLowlevelStorageException || ex instanceof DatastreamNotFoundException) { LOGGER.warn("Resource not found: " + ex.getMessage() + "; unable to fulfill REST API request", ex); return Response.status(Status.NOT_FOUND).entity(ex.getMessage()).type("text/plain").build(); } else if (ex instanceof AuthzException) { LOGGER.warn("Authorization failed; unable to fulfill REST API request", ex); return Response.status(Status.UNAUTHORIZED).entity(ex.getMessage()).type("text/plain").build(); } else if (ex instanceof IllegalArgumentException) { LOGGER.warn("Bad request; unable to fulfill REST API request", ex); return Response.status(Status.BAD_REQUEST).entity(ex.getMessage()).type("text/plain").build(); } else if (ex instanceof ObjectLockedException || ex instanceof DatastreamLockedException) { LOGGER.warn("Lock exception; unable to fulfill REST API request", ex); return Response.status(Status.CONFLICT).entity(ex.getMessage()).type(MediaType.TEXT_PLAIN).build(); } else if (ex instanceof ObjectValidityException) { LOGGER.warn("Validation exception; unable to fulfill REST API request", ex); if (((ObjectValidityException) ex).getValidation() != null) { DefaultSerializer serializer = new DefaultSerializer("n/a", getContext()); String errors = serializer.objectValidationToXml(((ObjectValidityException) ex).getValidation()); return Response.status(Status.BAD_REQUEST).entity(errors).type(MediaType.TEXT_XML).build(); } else { return Response.status(Status.BAD_REQUEST).entity(ex.getMessage()).type(MediaType.TEXT_PLAIN) .build(); } } else { LOGGER.error("Unexpected error fulfilling REST API request", ex); throw new WebApplicationException(ex); } } protected Response handleException(Exception ex, boolean flash) { Response error = handleException(ex); if (flash) error = Response.ok(error.getEntity()).build(); return error; } }