Web Content Management: Custom error pages

Summary:
This document provides an example of how WCM administrators can create a servlet filter to intercept an HTTP request / response and redirect users to custom pages based on the status.  A filter will allow you to intercept requests and perform some processing prior to the request reaching the servlet.  Filters also provide the ability to override and even return a custom response object.  This example will show you how to implement a filter that overrides the setStatus method on the HttpServletResponse and use it to redirect the user to a custom error404.html page when the servlet returns a 404 not found.

Sample attached below

The code  for a filter that can be used to return a customer error page when a status of 404 is returned:

package com.ibm.sample.filters;

import javax.servlet.*;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;

import javax.servlet.Filter;
import java.io.*;


public class SampleResponseFilter implements Filter {
    private FilterConfig filterConfig = null;

    public void init(FilterConfig filerConfig) {
            this.filterConfig = filterConfig;
    }

    public void destroy()
    // Called by the web container to indicate to a filter that it is being taken out of service.
    {
            filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
                    FilterChain chain) throws IOException, ServletException {
       
        // Create a wrappedResponse object done before chain.doFilter as this is what is passed to the servlet
            HttpServletResponse httpResp = (HttpServletResponse) response;
            ResponseStatusWrapper wrappedResponse = new ResponseStatusWrapper(
                            httpResp);

            // Called by the container each time a request/response pair is passed through the chain due to a client request.
            chain.doFilter(request, wrappedResponse);

            // use getStatus to check for 404 after the fact
            Integer error404 = new Integer(404);
            if (wrappedResponse.getStatus().contains(error404.toString())) {
                    System.out.println("****  404 REDIRECTED TO CUSTOM PAGE ****");
            }
    }
}


package com.ibm.sample.filters;

import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.http.*;



public class ResponseStatusWrapper extends HttpServletResponseWrapp er {
    private ArrayList status = null;
   
    public ResponseStatusWrapper(HttpServletResponse response)
    {
            super(response);
            status = new ArrayList(1);                                
    }
   
    public ArrayList getStatus()
    {
            return status;
    }
    //override the setStatus method
    public void setStatus( int currentStatus) {
            System.out.println(currentStatus);
   
            Integer intStatus = new Integer(currentStatus);
            status.add(intStatus.toString());
            HttpServletResponse httpResponse;
           
            //Update the original response depending on status
            if ( currentStatus != 404)
            {
                    // If the status is not 404 be transparent just set the status
                    httpResponse = (HttpServletResponse) this.getResponse();
                    httpResponse.setStatus(intStatus.intValue());
            } else
                    // If the status is 404 then send a redirect URL
                    httpResponse = (HttpServletResponse) this.getResponse();
            try {
                    httpResponse.sendRedirect("http://tuttlec.raleigh.ibm.com:10038/wps/wcm/jsp/html/error1.html");
            } catch (IOException e) {System.out.println("ResponseStatusWrapper:  IOEXCEPTION");}
    }
   
}

Put the class files in the ../shared/app directory:
Once you have compiled the filter code take the package jar file in my case filters.jar and place it in the /shared app directory

Update the web.xml:
Locate the web.xml and add the following
/wp_profile/config/cells/tut/applications/wcm.ear/deployments/wcm/ilwwcm.war/WEB-INF/web.xml
/wp_profile/installedApps/tut/wcm.ear/ilwwcm.war/WEB-INF/web.xml



Finally, restart then server and request some page that will result in an error like:
http://localhost:10038/wps/wcm/myconnect/web+content/Corning/404Error

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