io.wcm.handler.media.impl.AbstractMediaFileServlet.java Source code

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Here is the source code for io.wcm.handler.media.impl.AbstractMediaFileServlet.java

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/*
 * #%L
 * wcm.io
 * %%
 * Copyright (C) 2014 wcm.io
 * %%
 * 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.
 * #L%
 */
package io.wcm.handler.media.impl;

import io.wcm.sling.commons.request.RequestPath;
import io.wcm.wcm.commons.caching.CacheHeader;
import io.wcm.wcm.commons.contenttype.ContentType;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
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.SlingSafeMethodsServlet;

/**
 * Stream binary data stored in a nt:file or nt:resource node.
 * Optional support for Content-Disposition header ("download_attachment").
 */
abstract class AbstractMediaFileServlet extends SlingSafeMethodsServlet {
    private static final long serialVersionUID = 1L;

    /**
     * Selector for forcing a "save-as" dialog in the browser
     */
    public static final String SELECTOR_DOWNLOAD = "download_attachment";

    /**
     * Content disposition header
     */
    public static final String HEADER_CONTENT_DISPOSITION = "Content-Disposition";

    @Override
    protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response)
            throws ServletException, IOException {

        // get binary data resource
        Resource resource = getBinaryDataResource(request);
        if (resource == null) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }

        // check if the resource was modified since last request
        if (isNotModified(resource, request, response)) {
            return;
        }

        // get binary data and send to client
        byte[] binaryData = getBinaryData(resource, request);
        if (binaryData == null || binaryData.length == 0) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
        } else {
            String contentType = getContentType(resource, request);
            sendBinaryData(binaryData, contentType, request, response);
        }

    }

    /**
     * Get resource containing the binary data to deliver.
     * @param request Request
     * @return Resource pointing to nt:file or nt:resource node
     */
    protected Resource getBinaryDataResource(SlingHttpServletRequest request) {
        return request.getResource();
    }

    /**
     * Checks if the resource was modified since last request
     * @param resource Resource pointing to nt:file or nt:resource node
     * @param request Request
     * @param response Response
     * @return true if the resource is not modified and should not be delivered anew
     * @throws IOException
     */
    protected boolean isNotModified(Resource resource, SlingHttpServletRequest request,
            SlingHttpServletResponse response) throws IOException {
        // check resource's modification date against the If-Modified-Since header and send 304 if resource wasn't modified
        // never send expires header on author or publish instance (performance optimization - if medialib items changes
        // users have to refresh browsers cache)
        return CacheHeader.isNotModified(resource, request, response, false);
    }

    /**
     * Get binary data from the referenced nt:file or nt:resourcer resource.
     * @param resource Resource
     * @return Binary data or null if not binary data found
     * @throws IOException
     */
    protected byte[] getBinaryData(Resource resource, SlingHttpServletRequest request) throws IOException {
        InputStream is = resource.adaptTo(InputStream.class);
        if (is == null) {
            return null;
        }
        try {
            return IOUtils.toByteArray(is);
        } finally {
            is.close();
        }
    }

    /**
     * Get content type from the reference nt:file or nt:resourcer resource.
     * @param resource Resource
     * @return Content type (never null)
     */
    protected String getContentType(Resource resource, SlingHttpServletRequest request) {
        String mimeType = JcrBinary.getMimeType(resource);
        if (StringUtils.isEmpty(mimeType)) {
            mimeType = ContentType.OCTET_STREAM;
        }
        return mimeType;
    }

    /**
     * Send binary data to output stream. Respect optional content disposition header handling.
     * @param binaryData Binary data array.
     * @param contentType Content type
     * @param request Request
     * @param response Response
     * @throws IOException
     */
    protected void sendBinaryData(byte[] binaryData, String contentType, SlingHttpServletRequest request,
            SlingHttpServletResponse response) throws IOException {

        // set content type and length
        response.setContentType(contentType);
        response.setContentLength(binaryData.length);

        // Handling of the "force download" selector
        if (RequestPath.hasSelector(request, SELECTOR_DOWNLOAD)) {
            // Overwrite MIME type with one suited for downloads
            response.setContentType(ContentType.DOWNLOAD);

            // Construct disposition header
            StringBuilder dispositionHeader = new StringBuilder("attachment;");
            String suffix = request.getRequestPathInfo().getSuffix();
            suffix = StringUtils.stripStart(suffix, "/");
            if (StringUtils.isNotEmpty(suffix)) {
                dispositionHeader.append("filename=\"").append(suffix).append('\"');
            }

            response.setHeader(HEADER_CONTENT_DISPOSITION, dispositionHeader.toString());
        }

        // write binary data
        OutputStream out = response.getOutputStream();
        out.write(binaryData);
        out.flush();

    }

}