Java tutorial
/* * eXist Open Source Native XML Database * Copyright (C) 2014 The eXist Project * http://exist-db.org * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ package org.exist.mongodb.xquery.gridfs; import com.mongodb.DB; import com.mongodb.DBObject; import com.mongodb.MongoClient; import com.mongodb.MongoException; import com.mongodb.gridfs.GridFS; import com.mongodb.gridfs.GridFSDBFile; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.zip.GZIPInputStream; import org.apache.commons.io.IOUtils; import org.apache.commons.lang3.StringUtils; import org.bson.types.ObjectId; import org.exist.dom.QName; import org.exist.http.servlets.RequestWrapper; import org.exist.http.servlets.ResponseWrapper; import org.exist.mongodb.shared.Constants; import static org.exist.mongodb.shared.Constants.ACCEPT_ENCODING; import static org.exist.mongodb.shared.Constants.GZIP; import static org.exist.mongodb.shared.Constants.EXIST_COMPRESSION; import static org.exist.mongodb.shared.Constants.EXIST_ORIGINAL_SIZE; import static org.exist.mongodb.shared.FunctionDefinitions.PARAMETER_AS_ATTACHMENT; import static org.exist.mongodb.shared.FunctionDefinitions.PARAMETER_BUCKET; import static org.exist.mongodb.shared.FunctionDefinitions.PARAMETER_DATABASE; import static org.exist.mongodb.shared.FunctionDefinitions.PARAMETER_FILENAME; import static org.exist.mongodb.shared.FunctionDefinitions.PARAMETER_MONGODB_CLIENT; import static org.exist.mongodb.shared.FunctionDefinitions.PARAMETER_OBJECTID; import org.exist.mongodb.shared.MongodbClientStore; import org.exist.mongodb.xquery.GridfsModule; import org.exist.util.MimeTable; import org.exist.util.MimeType; import org.exist.xquery.BasicFunction; import org.exist.xquery.Cardinality; import org.exist.xquery.FunctionSignature; import org.exist.xquery.Variable; import org.exist.xquery.XPathException; import org.exist.xquery.XQueryContext; import org.exist.xquery.functions.request.RequestModule; import org.exist.xquery.functions.response.ResponseModule; import org.exist.xquery.value.FunctionReturnSequenceType; import org.exist.xquery.value.JavaObjectValue; import org.exist.xquery.value.Sequence; import org.exist.xquery.value.SequenceType; import org.exist.xquery.value.Type; /** * Functions to retrieve documents from GridFS as a stream. * * @author Dannes Wessels */ public class Stream extends BasicFunction { private static final String FIND_BY_OBJECTID = "stream-by-objectid"; private static final String FIND_BY_FILENAME = "stream-by-filename"; public final static FunctionSignature signatures[] = { new FunctionSignature(new QName(FIND_BY_FILENAME, GridfsModule.NAMESPACE_URI, GridfsModule.PREFIX), "Retrieve document by filename as stream", new SequenceType[] { PARAMETER_MONGODB_CLIENT, PARAMETER_DATABASE, PARAMETER_BUCKET, PARAMETER_FILENAME, PARAMETER_AS_ATTACHMENT }, new FunctionReturnSequenceType(Type.EMPTY, Cardinality.EMPTY, Constants.DESCR_OUTPUT_STREAM)), new FunctionSignature(new QName(FIND_BY_OBJECTID, GridfsModule.NAMESPACE_URI, GridfsModule.PREFIX), "Retrieve document by objectid as stream", new SequenceType[] { PARAMETER_MONGODB_CLIENT, PARAMETER_DATABASE, PARAMETER_BUCKET, PARAMETER_OBJECTID, PARAMETER_AS_ATTACHMENT }, new FunctionReturnSequenceType(Type.EMPTY, Cardinality.EMPTY, Constants.DESCR_OUTPUT_STREAM)), }; public Stream(XQueryContext context, FunctionSignature signature) { super(context, signature); } @Override public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException { try { // Verify clientid and get client String mongodbClientId = args[0].itemAt(0).getStringValue(); MongodbClientStore.getInstance().validate(mongodbClientId); MongoClient client = MongodbClientStore.getInstance().get(mongodbClientId); // Get parameters String dbname = args[1].itemAt(0).getStringValue(); String bucket = args[2].itemAt(0).getStringValue(); String documentId = args[3].itemAt(0).getStringValue(); Boolean setDisposition = args[4].itemAt(0).toJavaObject(Boolean.class); // Get database DB db = client.getDB(dbname); // Creates a GridFS instance for the specified bucket GridFS gfs = new GridFS(db, bucket); // Find one document by id or by filename GridFSDBFile gfsFile = (isCalledAs(FIND_BY_OBJECTID)) ? gfs.findOne(new ObjectId(documentId)) : gfs.findOne(documentId); stream(gfsFile, documentId, setDisposition); } catch (XPathException ex) { LOG.error(ex.getMessage(), ex); throw new XPathException(this, ex.getMessage(), ex); } catch (MongoException ex) { LOG.error(ex.getMessage(), ex); throw new XPathException(this, GridfsModule.GRFS0002, ex.getMessage()); } catch (Throwable ex) { LOG.error(ex.getMessage(), ex); throw new XPathException(this, GridfsModule.GRFS0003, ex.getMessage()); } return Sequence.EMPTY_SEQUENCE; } /** * Stream document to HTTP agent */ void stream(GridFSDBFile gfsFile, String documentId, Boolean setDisposition) throws IOException, XPathException { if (gfsFile == null) { throw new XPathException(this, GridfsModule.GRFS0004, String.format("Document '%s' could not be found.", documentId)); } DBObject metadata = gfsFile.getMetaData(); // Determine actual size String compression = (metadata == null) ? null : (String) metadata.get(EXIST_COMPRESSION); Long originalSize = (metadata == null) ? null : (Long) metadata.get(EXIST_ORIGINAL_SIZE); long length = gfsFile.getLength(); if (originalSize != null) { length = originalSize; } // Stream response stream ResponseWrapper rw = getResponseWrapper(context); // Set HTTP Headers rw.addHeader(Constants.CONTENT_LENGTH, String.format("%s", length)); // Set filename when required String filename = determineFilename(documentId, gfsFile); if (setDisposition && StringUtils.isNotBlank(filename)) { rw.addHeader(Constants.CONTENT_DISPOSITION, String.format("attachment;filename=%s", filename)); } String contentType = getMimeType(gfsFile.getContentType(), filename); if (contentType != null) { rw.setContentType(contentType); } boolean isGzipSupported = isGzipEncodingSupported(context); // Stream data if ((StringUtils.isBlank(compression))) { // Write data as-is, no marker available that data is stored compressed try (OutputStream os = rw.getOutputStream()) { gfsFile.writeTo(os); os.flush(); } } else { if (isGzipSupported && StringUtils.contains(compression, GZIP)) { // Write compressend data as-is, since data is stored as gzipped data and // the agent suports it. rw.addHeader(Constants.CONTENT_ENCODING, GZIP); try (OutputStream os = rw.getOutputStream()) { gfsFile.writeTo(os); os.flush(); } } else { // Write data uncompressed try (OutputStream os = rw.getOutputStream()) { InputStream is = gfsFile.getInputStream(); try (GZIPInputStream gzis = new GZIPInputStream(is)) { IOUtils.copyLarge(gzis, os); os.flush(); } } } } } /** * Get filename from the provided filename, or as stored in the database * when blank e.g because document is referenced by documentID */ private String determineFilename(String documentId, GridFSDBFile gfsFile) { String documentName = null; // Use filename when it is passed to method if (isCalledAs(FIND_BY_FILENAME) && StringUtils.isNotBlank(documentId)) { documentName = documentId; } // If documentname is not set, retrieve from database if (StringUtils.isBlank(documentName)) { documentName = gfsFile.getFilename(); } return documentName; } /** * Get mime-type: from stored value or from file name. Value NULL has not * existent or blank. */ private String getMimeType(String storedType, String filename) throws XPathException { String mimeType = storedType; // When no data is found get from filename if (StringUtils.isBlank(mimeType) && StringUtils.isNotBlank(filename)) { MimeType mime = MimeTable.getInstance().getContentTypeFor(filename); mimeType = mime.getName(); } // Nothing could be found if (StringUtils.isBlank(mimeType)) { LOG.debug(String.format("Content type for %s could not be retrieved from database or document name.", filename)); mimeType = null; // force NULL } return mimeType; } /** * Get the Response wrapper which provides access to the servlet outputstream. * * @throws XPathException Thrown when something bad happens. */ private ResponseWrapper getResponseWrapper(XQueryContext context) throws XPathException { ResponseModule myModule = (ResponseModule) context.getModule(ResponseModule.NAMESPACE_URI); // response object is read from global variable $response Variable respVar = myModule.resolveVariable(ResponseModule.RESPONSE_VAR); if (respVar == null) { throw new XPathException(this, "No response object found in the current XQuery context."); } if (respVar.getValue().getItemType() != Type.JAVA_OBJECT) { throw new XPathException(this, "Variable $response is not bound to an Java object."); } JavaObjectValue respValue = (JavaObjectValue) respVar.getValue().itemAt(0); if (!"org.exist.http.servlets.HttpResponseWrapper".equals(respValue.getObject().getClass().getName())) { throw new XPathException(this, signatures[1].toString() + " can only be used within the EXistServlet or XQueryServlet"); } ResponseWrapper response = (ResponseWrapper) respValue.getObject(); return response; } /** * Get the Request wrapper which provides access to the servlet * outputstream. * * @throws XPathException Thrown when something bad happens. */ private RequestWrapper getRequestWrapper(XQueryContext context) throws XPathException { RequestModule myModule = (RequestModule) context.getModule(RequestModule.NAMESPACE_URI); // request object is read from global variable $request Variable respVar = myModule.resolveVariable(RequestModule.REQUEST_VAR); if (respVar == null) { throw new XPathException(this, "No request object found in the current XQuery context."); } if (respVar.getValue().getItemType() != Type.JAVA_OBJECT) { throw new XPathException(this, "Variable $request is not bound to an Java object."); } JavaObjectValue respValue = (JavaObjectValue) respVar.getValue().itemAt(0); if (!"org.exist.http.servlets.HttpRequestWrapper".equals(respValue.getObject().getClass().getName())) { throw new XPathException(this, signatures[1].toString() + " can only be used within the EXistServlet or XQueryServlet"); } RequestWrapper request = (RequestWrapper) respValue.getObject(); return request; } /** * Verify if HTTP agent supports GZIP content encoding. */ private boolean isGzipEncodingSupported(XQueryContext context) { try { RequestWrapper request = getRequestWrapper(context); String content = request.getHeader(ACCEPT_ENCODING); if (StringUtils.contains(content, GZIP)) { return true; } } catch (XPathException ex) { LOG.error(ex.getMessage(), ex); } return false; } }