Oak Direct Binary Download

ImageSignedUrlRedirectServlet.java

package com.chrisp.rde.core.servlets;

import org.apache.commons.lang3.StringUtils;
import org.apache.jackrabbit.api.binary.BinaryDownload;
import org.apache.jackrabbit.api.binary.BinaryDownloadOptions;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.servlets.OptingServlet;
import org.apache.sling.api.servlets.SlingSafeMethodsServlet;
import org.apache.sling.servlets.annotations.SlingServletResourceTypes;
import org.osgi.service.component.annotations.Component;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.jcr.Binary;
import javax.jcr.Node;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import java.io.IOException;
import java.net.URI;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

@Component(service = {Servlet.class})
@SlingServletResourceTypes(
        resourceTypes = "dam/Asset",
        methods = "GET",
        selectors = "woi"
)
/**
 * Returns a redirect to the cloud storage of the underlying original asset when `woi` selector added.
 * e.g. https://author-p31359-e934772.adobeaemcloud.com/content/dam/xxxx/sample.jpg.woi/image.png
 */
public class ImageSignedUrlRedirectServlet extends SlingSafeMethodsServlet implements OptingServlet {

    private static final Logger log = LoggerFactory.getLogger(ImageSignedUrlRedirectServlet.class);

    public static final String DEFAULT_FILENAME_PATTERN = "(image|img)\\.(.+)";

    private final Pattern lastSuffixPattern = Pattern.compile(DEFAULT_FILENAME_PATTERN);


    /**
     * Only accept requests that.
     * - Are not null
     * - Have a suffix that matches the image file name pattern
     * @param request SlingRequest object
     * @return true if the Servlet should handle the request
     */
    @Override
    public final boolean accepts(final SlingHttpServletRequest request) {
        if (request == null) {
            return false;
        }

        final String suffix = request.getRequestPathInfo().getSuffix();
        if (StringUtils.isBlank(suffix)) {
            log.info("no suffix");
            return false;
        }

        final String lastSuffix = PathInfoUtil.getLastSuffixSegment(request);
        final Matcher matcher = lastSuffixPattern.matcher(lastSuffix);

        final boolean match = matcher.matches();
        log.info("match {} ", match);
        return match;
    }

    @Override
    protected final void doGet(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws
            ServletException, IOException {
        final Resource resource = request.getResource();
        if (!isAsset(resource)) {
            response.setStatus(404);
            log.info("not an asset");
            return;
        }

        try {
            final Resource rendition = resource.getChild("jcr:content/renditions/original");
            final Node ntFile = rendition.adaptTo(Node.class);
            final Node ntResource = ntFile.getNode("jcr:content");
            final Binary binary = ntResource.getProperty("jcr:data").getBinary();

            if (binary instanceof BinaryDownload) {
                final BinaryDownload binaryDownload = (BinaryDownload) binary;
                final BinaryDownloadOptions.BinaryDownloadOptionsBuilder builder = BinaryDownloadOptions.builder()
                    .withFileName(ntFile.getName())
                    .withMediaType(ntResource.getProperty("jcr:mimeType").getString());

                if (ntResource.hasProperty("jcr:encoding")) {
                    builder.withCharacterEncoding(ntResource.getProperty("jcr:encoding").getString());
                }

                final URI uri = binaryDownload.getURI(builder.build());
                log.info("redirect: {}", uri);
                response.sendRedirect(uri.toString());
            }
        } catch (Throwable e) {
            log.error("Exception fetching signed url", e);
            response.setStatus(500);
        }
    }

    public static boolean isAsset(Resource resource) {
        return null != resource && "dam:Asset".equals(resource.getResourceType());
    }

}