[CONF] Apache Wicket: WicketApplicationFilter (page edited)

Sat, 19 Apr 2008 00:12:26 -0700

Page Edited : WICKET : WicketApplicationFilter

WicketApplicationFilter has been edited by Erik van Oosten (Apr 19, 2008).

(View changes)

Content:

Using @SpringBean beyond Wicket

Sometimes a web application also contains some non-Wicket stuff. For example you might use Restlets. You can still use the @SpringBean annotation in that code. The only prerequisite is that the Wicket application instance is set in a thread local variable. Use the filter given below to accomplish this. Make sure that in web.xml the filter is configured /after/ the Wicket filter. This approach does not work in combination with the Wicket-servlet.

Example web.xml fragment:

<filter>
    <filter-name>wicket.filter</filter-name>
    <filter-class>org.apache.wicket.protocol.http.WicketFilter</filter-class>
    <init-param>
      <param-name>applicationFactoryClassName</param-name>
      <param-value>org.apache.wicket.spring.SpringWebApplicationFactory</param-value>
    </init-param>
  </filter>

  <filter>
    <filter-name>wicket.application.filter</filter-name>
    <filter-class>com.tipspot.site.util.WicketApplicationFilter</filter-class>
    <init-param>
      <param-name>wicketFilterName</param-name>
      <param-value>wicket.filter</param-value>
    </init-param>
  </filter>

  <filter-mapping>
    <filter-name>wicket.filter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <filter-mapping>
    <filter-name>wicket.application.filter</filter-name>
    <url-pattern>/rest/*</url-pattern>
  </filter-mapping>

Here is the filter:

package com.example.wicket.filter;

import org.apache.wicket.Application;
import org.apache.wicket.protocol.http.WebApplication;

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

/**
 * Filter that sets the wicket application, just like [EMAIL PROTECTED] org.apache.wicket.protocol.http.WicketFilter}
 * would do.
 *
 * <p>This implementation assumes that it is placed in a filter chain, <i>after</i> WicketFilter,
 * for URLs that are not handled by the WicketFilter.
 *
 * <p>The filter name of the wicket filter is retrieved from the init parameter wicketFilterName.
 *
 * @author Erik van Oosten
 */
public class WicketApplicationFilter implements Filter {

    private WebApplication webApplication;

    public void init(FilterConfig filterConfig) throws ServletException {
        // Get instance of the Wicket application, it is set by the Wicket filter.
        String contextKey = "wicket:" + filterConfig.getInitParameter("wicketFilterName");
        webApplication = (WebApplication) filterConfig.getServletContext().getAttribute(contextKey);

        if (webApplication == null) {
            throw new ServletException("Could not find the Wicket application, please make " +
                    "sure filter WicketApplicationFilter is embedded in Wicket's filter");
        }
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        try {
            // Set the webapplication for this thread
            Application.set(webApplication);

            chain.doFilter(request, response);

        } finally {
            // always unset the application thread local
            Application.unset();
        }
    }

    public void destroy() {
        webApplication = null;
    }
}

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