Example: Extending PageListServlet

The following example shows how a servlet extends the PageListServlet class and determines the markup-language type required by the client. The servlet then uses the callPage() method to call an appropriate JavaServer Pages (JSP) file. In this example, the JSP file that provides the the correct markup-language for the response is Hello.page.

public class HelloPervasiveServlet extends PageListServlet implements Serializable
{
     /*
     * doGet -- Process incoming HTTP GET requests
     */
    public  void doGet HttpServletRequest(request, HttpServletResponse response)
    throws IOException, ServletException
    {
       // Name of the page to be called...
       String pageName = "Hello.page";
 
       // First check if the servlet was invoked with a queryString that contains 
          // a markup-language value.
       // For example, if this is how the  servlet is invoked...
       //  http://localhost/servlets/HeloPervasive?mlname=VXML
       //  then use the following method...
       String mlname= getMLNameFromRequest(request);

        // If no markup language type is provided in the queryString, 
        // then try to determine the client
        // Type from the request, and use the markup-language name configured in 
        // the client_types.xml file.   
        if (mlName == null)
        {
          mlName = getMLTypeFromRequest(request);
         }
         try
         {
           // Serve the request page.
           callPage(mlName, pageName, request, response);
          }
          catch  Exception(e)
          { 
            handleError(mlName, request, response, e);
           }
       }
}

 

See Also

Page lists
Webapplications: Resources for learning
client_types.xml
Client type detection support

 

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