# AbstractHandlerCommons.java

    /*
    ** Module   : AbstractHandlerCommons.java
    ** Abstract : an abstract class used to load modules
    **
    ** Copyright (c) 2014-2021, Golden Code Development Corporation.

    **
    ** -#- -I- --Date-- -------------------------------Description-----------------------------------
    ** 001 MAG 20140708 First version. Code moved from DojoToolkitHandler.
    ** 002 GES 20150308 Moved to a more generic package location.
    ** 003 SBI 20210413 Errata fix for detectContentType.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.web;

    import java.io.*;
    import java.net.*;

    import javax.servlet.http.*;

    import org.eclipse.jetty.server.handler.*;

    /**
     * This abstract class contains the common part of handlers which load javascript modules
     * or other classpath resources like Dojo toolkit.
     */
    public abstract class AbstractHandlerCommons
    extends AbstractHandler
    {
       /** Buffer size. */
       private static final int BUFFER_SIZE = 4096;

       /** Data buffer. */
       private byte[] buffer = new byte[BUFFER_SIZE];

       /**
        * Build HTTP response.
        *
        * @param   response
        *          The object or a wrapper of the response.
        * @param   conn
        *          Module resource.
        * @param   module
        *          Module name.
        *
        * @throws  IOException
        *          On I/O errors.
        */
       protected void sendResponse(HttpServletResponse response, URLConnection conn, String module)
       throws IOException
       {
          // set response headers and status
          response.setStatus(HttpServletResponse.SC_OK);
          response.setContentType(detectContentType(module));
          response.setContentLength(conn.getContentLength());

          // build response body
          InputStream is = conn.getInputStream();
          OutputStream os = response.getOutputStream();

          int bytesRead = is.read(buffer);
          while (bytesRead > 0)
          {
             os.write(buffer, 0, bytesRead);
             bytesRead = is.read(buffer);
          }

          // cleanup
          os.flush();
          is.close();
       }

       /**
        * Detect content type based on module file extension.
        *
        * @param   module
        *          Module name.
        *
        * @return  Content type (MIME).
        */
       protected String detectContentType(String module)
       {
          String contentType = "application/octet-stream";

          if (module.endsWith(".js"))
          {
             contentType = "application/javascript";
          }
          else if (module.endsWith(".css"))
          {
             contentType = "text/css";
          }
          else if (module.endsWith(".gif"))
          {
             contentType = "image/gif";
          }
          else if (module.endsWith(".png"))
          {
             contentType = "image/png";
          }
          else if (module.endsWith(".jpg") || module.endsWith(".jpeg"))
          {
             contentType = "image/jpeg";
          }
          else if (module.endsWith(".html") || module.endsWith(".htm"))
          {
             contentType = "text/html";
          }

          return contentType;
       }
    }