ExternalAttachmentDownloadLink.java

/*
 * Copyright 2014 James Pether Sörling
 *
 * 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.
 *
 *  $Id$
 *  $HeadURL$
*/
package com.hack23.cia.web.impl.ui.application.views.common.pagelinks.impl;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.server.StreamResource;
import com.vaadin.ui.Link;

/**
 * The Class ExternalAttachmentDownloadLink.
 */
public final class ExternalAttachmentDownloadLink extends Link {

    /** The Constant serialVersionUID. */
    private static final long serialVersionUID = 1L;

    /** The Constant LOGGER. */
    private static final Logger LOGGER = LoggerFactory.getLogger(ExternalAttachmentDownloadLink.class);

    /** The file name. */
    private final String fileName;

    /** The file type. */
    private final String fileType;

    /** The file url. */
    private final String fileUrl;

    /**
     * Instantiates a new external attachment download link.
     *
     * @param fileName
     *            the file name
     * @param fileType
     *            the file type
     * @param fileUrl
     *            the file url
     */
    public ExternalAttachmentDownloadLink(final String fileName, final String fileType, final String fileUrl) {
        super();
        this.fileName = fileName;
        this.fileType = fileType;
        this.fileUrl = fileUrl;
        setCaption(fileName);
        setDescription("Download " + fileName);
        setTargetName("_blank");
    }

    @Override
    public void attach() {
        super.attach();

        final StreamResource.StreamSource source = new StreamResource.StreamSource() {

            /** The Constant serialVersionUID. */
            private static final long serialVersionUID = 1L;

            @Override
            public InputStream getStream() {

                try {
                    return new URL(fileUrl).openStream();
                } catch (final IOException e) {
                    LOGGER.warn("Problem opening url:"+ fileUrl,e);
                    return new ByteArrayInputStream(new byte[0]);
                }
            }
        };

        final StreamResource resource = new StreamResource(source, fileName);

        resource.getStream().setParameter("Content-Disposition", "attachment;filename=\"" + fileName + "\"");
        resource.setMIMEType("application/" + fileType);
        resource.setCacheTime(0);

        setResource(resource);
    }
}