netinf.node.cache.peerside.PeersideServlet.java Source code

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Here is the source code for netinf.node.cache.peerside.PeersideServlet.java

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/*
 * Copyright (C) 2009-2011 University of Paderborn, Computer Networks Group
 * (Full list of owners see http://www.netinf.org/about-2/license)
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,
 *       this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 *     * Neither the name of the University of Paderborn nor the names of its contributors may be used to endorse
 *       or promote products derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package netinf.node.cache.peerside;

import java.io.ByteArrayInputStream;
import java.io.IOException;

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

import net.sf.ehcache.Cache;
import net.sf.ehcache.Element;

import org.apache.commons.io.IOUtils;

/**
 * Simple HttpServlet serving elements stored in the PeersideCache. Allowed HTTP methods are HEAD and GET. The Range header is
 * supported as well.
 * 
 * @author PG NetInf 3, University of Paderborn.
 */
public class PeersideServlet extends HttpServlet {

    private static final long serialVersionUID = 2029221260528771761L;
    private Cache cache;

    /**
     * Constructor.
     * 
     * @param cache
     *           The adapted cache.
     */
    public PeersideServlet(Cache cache) {
        this.cache = cache;
    }

    /**
     * HEAD and GET operations.
     * 
     * @param req
     *           The Request.
     * @param resp
     *           The response.
     * @param writeContent
     * @throws IOException
     */
    private void doHeadOrGet(HttpServletRequest req, HttpServletResponse resp, boolean writeContent)
            throws IOException {
        String elementKey = req.getPathInfo();
        if (elementKey.startsWith("/") && elementKey.length() >= 1) {
            elementKey = elementKey.substring(1);
        }
        Element element = cache.get(elementKey);
        if (element == null) {
            resp.setStatus(HttpServletResponse.SC_NOT_FOUND);
        } else {
            byte[] content = (byte[]) element.getValue();
            String range = req.getHeader("Range");
            if (range != null) {
                if (range.matches("^bytes=(\\d+-\\d*|-\\d+)$")) {
                    int contentLength = content.length;
                    int offset = 0;
                    int length = contentLength;
                    range = range.split("=")[1];
                    if (range.startsWith("-")) {
                        offset = contentLength - Integer.parseInt(range.substring(1));
                    } else if (range.endsWith("-")) {
                        offset = Integer.parseInt(range.substring(0, range.length() - 1));
                    } else {
                        String[] rangeParts = range.split("-");
                        offset = Integer.parseInt(rangeParts[0]);
                        length = Integer.parseInt(rangeParts[1]) + 1;
                    }
                    if (offset <= length && offset <= contentLength) {
                        length = length > contentLength ? contentLength : length;
                        resp.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
                        resp.setContentLength(length - offset);
                        resp.setHeader("Accept-Ranges", "bytes");
                        resp.setHeader("Content-Range", offset + "-" + (length - 1) + "/" + contentLength);
                        if (writeContent) {
                            IOUtils.copy(new ByteArrayInputStream(content, offset, length - offset),
                                    resp.getOutputStream());
                        }
                    } else {
                        resp.setStatus(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                    }
                } else {
                    resp.setStatus(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                }
            } else {
                resp.setStatus(HttpServletResponse.SC_OK);
                resp.setContentLength(content.length);
                resp.setHeader("Accept-Ranges", "bytes");
                if (writeContent) {
                    IOUtils.copy(new ByteArrayInputStream(content), resp.getOutputStream());
                }
            }
        }
    }

    @Override
    protected void doHead(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doHeadOrGet(req, resp, false);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doHeadOrGet(req, resp, true);
    }

    @Override
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String elementKey = req.getPathInfo();
        if (elementKey.startsWith("/") && elementKey.length() >= 1) {
            elementKey = elementKey.substring(1);
        }
        if (elementKey.equals("*")) {
            cache.removeAll();
        } else {
            cache.remove(elementKey);
        }
        resp.setStatus(HttpServletResponse.SC_NO_CONTENT);
    }
}