org.sakaiproject.scorm.ui.player.util.ContentPackageWebResource.java Source code

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Here is the source code for org.sakaiproject.scorm.ui.player.util.ContentPackageWebResource.java

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/**
 * Copyright (c) 2007 The Apereo Foundation
 *
 * Licensed under the Educational Community 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://opensource.org/licenses/ecl2
 *
 * 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.
 */
package org.sakaiproject.scorm.ui.player.util;

import org.apache.wicket.Application;
import org.apache.wicket.RequestCycle;
import org.apache.wicket.markup.html.WebResource;
import org.apache.wicket.protocol.http.WebRequest;
import org.apache.wicket.protocol.http.WebResponse;
import org.apache.wicket.util.resource.IResourceStream;
import org.apache.wicket.util.time.Time;
import org.apache.wicket.util.watch.IModifiable;
import org.sakaiproject.scorm.model.api.ContentPackageResource;

public class ContentPackageWebResource extends WebResource implements IModifiable {

    private static final long serialVersionUID = 1L;

    private static final String[] candidateCompressionContentTypes = { "text/html", "text/javascript", "text/css" };

    private ContentPackageResource resource;
    private ContentPackageResourceStream resourceStream;

    public ContentPackageWebResource(ContentPackageResource resource) {
        setCacheable(true);
        this.resource = resource;
        this.resourceStream = new ContentPackageResourceStream(resource);
    }

    @Override
    public IResourceStream getResourceStream() {

        if (canCompress()) {
            return new CompressingContentPackageResourceStream(resource);
        }

        return resourceStream;
    }

    @Override
    protected void setHeaders(WebResponse response) {
        super.setHeaders(response);
        if (canCompress()) {
            response.setHeader("Content-Encoding", "gzip");
        }
    }

    private boolean canCompress() {
        return isCandidateForCompression() && supportsCompression();
    }

    private boolean isCandidateForCompression() {
        String contentType = resourceStream.getContentType();

        if (contentType != null)
            for (int i = 0; i < candidateCompressionContentTypes.length; i++)
                if (contentType.startsWith(candidateCompressionContentTypes[i]))
                    return true;

        return false;
    }

    private boolean supportsCompression() {
        if (Application.get().getResourceSettings().getDisableGZipCompression()) {
            return false;
        }
        if (RequestCycle.get() == null)
            return false;

        WebRequest request = (WebRequest) RequestCycle.get().getRequest();
        String s = request.getHttpServletRequest().getHeader("Accept-Encoding");
        if (s == null) {
            return false;
        } else {
            return s.indexOf("gzip") >= 0;
        }
    }

    public Time lastModifiedTime() {
        return resourceStream.lastModifiedTime();
    }
}