org.eclipse.osbp.xtext.table.common/src/org/eclipse/osbp/xtext/table/common/export/TemporaryFileDownloadResource.java

/**
 * Copyright 2011-2019 Jonathan Nash and others
 * 
 * Licensed 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.
 * 
 *  Contributors:                                                      
 * 	   Jonathan Nash - initial implementation
 * 	   Compex Systemhaus GmbH - adaptions for OSBP
 */
package org.eclipse.osbp.xtext.table.common.export;

import com.vaadin.server.DownloadStream;
import com.vaadin.server.StreamResource;
import com.vaadin.ui.UI;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.InputStream;

/**
 * The Class TemporaryFileDownloadResource.
 * 
 * Code obtained from: http://vaadin.com/forum/-/message_boards/view_message/159583
 */
public class TemporaryFileDownloadResource extends StreamResource {

    /** The Constant serialVersionUID. */
    private static final long serialVersionUID = 476307190141362413L;

    /** The filename. */
    private final String filename;

    /** The content type. */
    private String contentType;

    /**
     * Instantiates a new temporary file download resource.
     * 
     * @param application
     *            the application
     * @param fileName
     *            the file name
     * @param contentType
     *            the content type
     * @param tempFile
     *            the temp file
     * @throws FileNotFoundException
     *             the file not found exception
     */
    public TemporaryFileDownloadResource(final UI application, final String fileName,
            final String contentType, final File tempFile) throws FileNotFoundException {
        super(new FileStreamResource(tempFile), fileName);
        this.filename = fileName;
        this.contentType = contentType;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.vaadin.terminal.StreamResource#getStream()
     */
    @Override
    public DownloadStream getStream() {
        final DownloadStream stream =
                new DownloadStream(getStreamSource().getStream(), contentType, filename);
        stream.setParameter("Content-Disposition", "attachment;filename=" + filename);
        // This magic incantation should prevent anyone from caching the data
        stream.setParameter("Cache-Control", "private,no-cache,no-store");
        // In theory <=0 disables caching. In practice Chrome, Safari (and, apparently, IE) all
        // ignore <=0. Set to 1s
        stream.setCacheTime(1000);
        return stream;
    }

    /**
     * The Class FileStreamResource.
     */
    private static class FileStreamResource implements StreamResource.StreamSource {

        /** The Constant serialVersionUID. */
        private static final long serialVersionUID = 3801605481686085335L;

        /** The input stream.
         *  Made it transient per: https://github.com/jnash67/tableexport-for-vaadin/issues/28
         */
        private final transient InputStream inputStream;

        /**
         * Instantiates a new file stream resource.
         * 
         * @param fileToDownload
         *            the file to download
         * @throws FileNotFoundException
         *             the file not found exception
         */
        public FileStreamResource(final File fileToDownload) throws FileNotFoundException {
            inputStream = new DeletingFileInputStream(fileToDownload);
        }

        /*
         * (non-Javadoc)
         * 
         * @see com.vaadin.terminal.StreamResource.StreamSource#getStream()
         */
        @Override
        public InputStream getStream() {
            return inputStream;
        }
    }

}