Class ConcatServlet

  • All Implemented Interfaces:, javax.servlet.Servlet, javax.servlet.ServletConfig

    public class ConcatServlet
    extends javax.servlet.http.HttpServlet

    This servlet may be used to concatenate multiple resources into a single response.

    It is intended to be used to load multiple javascript or css files, but may be used for any content of the same mime type that can be meaningfully concatenated.

    The servlet uses RequestDispatcher.include(javax.servlet.ServletRequest, javax.servlet.ServletResponse) to combine the requested content, so dynamically generated content may be combined (Eg engine.js for DWR).

    The servlet uses parameter names of the query string as resource names relative to the context root. So these script tags:

     <script type="text/javascript" src="../js/behaviour.js"></script>
     <script type="text/javascript" src="../js/ajax.js"></script>
     <script type="text/javascript" src="../chat/chat.js"></script>

    can be replaced with the single tag (with the ConcatServlet mapped to /concat):

     <script type="text/javascript" src="../concat?/js/behaviour.js&/js/ajax.js&/chat/chat.js"></script>

    The ServletContext.getMimeType(String) method is used to determine the mime type of each resource. If the types of all resources do not match, then a 415 UNSUPPORTED_MEDIA_TYPE error is returned.

    If the init parameter development is set to true then the servlet will run in development mode and the content will be concatenated on every request.

    Otherwise the init time of the servlet is used as the lastModifiedTime of the combined content and If-Modified-Since requests are handled with 304 NOT Modified responses if appropriate. This means that when not in development mode, the servlet must be restarted before changed content will be served.

    See Also:
    Serialized Form
    • Constructor Summary

      Constructor Description
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected void doGet​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)  
      protected long getLastModified​(javax.servlet.http.HttpServletRequest req)  
      void init()  
      • Methods inherited from class javax.servlet.http.HttpServlet

        doDelete, doHead, doOptions, doPost, doPut, doTrace, service, service
      • Methods inherited from class javax.servlet.GenericServlet

        destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • ConcatServlet

        public ConcatServlet()
    • Method Detail

      • init

        public void init()
                  throws javax.servlet.ServletException
        init in class javax.servlet.GenericServlet
      • getLastModified

        protected long getLastModified​(javax.servlet.http.HttpServletRequest req)
        getLastModified in class javax.servlet.http.HttpServlet
      • doGet

        protected void doGet​(javax.servlet.http.HttpServletRequest request,
                             javax.servlet.http.HttpServletResponse response)
                      throws javax.servlet.ServletException,
        doGet in class javax.servlet.http.HttpServlet