/** * Licensed under the Artistic License; you may not use this file * except in compliance with the License. * You may obtain a copy of the License at * *      http://displaytag.sourceforge.net/license.html * * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. */package org.displaytag.filter;import java.io.IOException;import java.util.HashMap;import java.util.Map;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.lang.StringUtils;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.displaytag.Messages;import org.displaytag.tags.TableTag;import org.displaytag.tags.TableTagParameters;/** * <p> * Allow the author of an included JSP page to reset the content type to something else (like a binary stream), and then * write the new info back as the exclusive response, clearing the buffers of all previously added content. * </p> * <p> * This filter allows TableTag users to perform exports from pages that are run as includes, such as from Struts or a * jsp:include. If that is your intention, just add this Filter to your web.xml and map it to the appropriate requests, * using something like: * </p> *  * <pre> *  &lt;filter> *      &lt;filter-name>ResponseOverrideFilter&lt;/filter-name> *      &lt;filter-class>org.displaytag.filter.ResponseOverrideFilter&lt;/filter-class> *  &lt;/filter> *  &lt;filter-mapping> *      &lt;filter-name>ResponseOverrideFilter&lt;/filter-name> *      &lt;url-pattern>*.do&lt;/url-pattern> *  &lt;/filter-mapping> *  &lt;filter-mapping> *      &lt;filter-name>ResponseOverrideFilter&lt;/filter-name> *      &lt;url-pattern>*.jsp&lt;/url-pattern> *  &lt;/filter-mapping> * </pre> *  * <p> * By default the filter buffers all the export content before writing it out. You can set an optional parameter * <code>buffer</code> to <code>false</code> to make the filter write directly to the output stream. This could be * faster and uses less memory, but the content length will not be set. * </p> *  * <pre> *  &lt;filter> *      &lt;filter-name>ResponseOverrideFilter&lt;/filter-name> *      &lt;filter-class>org.displaytag.filter.ResponseOverrideFilter&lt;/filter-class> *      &lt;init-param> *          &lt;param-name>buffer&lt;/param-name> *          &lt;param-value>false&lt;/param-value> *      &lt;/init-param> *  &lt;/filter> *  </pre> *  * @author rapruitt * @author Fabrizio Giustina * @version $Revision: 1081 $ ($Author: fgiust $) */public class ResponseOverrideFilter implements Filter{    /**     * Logger.     */    private Log log;    /**     * Force response buffering. Enabled by default.     */    private boolean buffer = true;    /**     * {@inheritDoc}     */    public void init(FilterConfig filterConfig)    {        log = LogFactory.getLog(ResponseOverrideFilter.class);        String bufferParam = filterConfig.getInitParameter("buffer");        if (log.isDebugEnabled())        {            log.debug("bufferParam=" + bufferParam);        }        buffer = bufferParam == null || StringUtils.equalsIgnoreCase("true", bufferParam);        log.info("Filter initialized. Response buffering is " + (buffer ? "enabled" : "disabled"));    }    /**     * {@inheritDoc}     */    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)        throws IOException, ServletException    {        if (servletRequest.getParameter(TableTagParameters.PARAMETER_EXPORTING) == null)        {            if (log.isDebugEnabled())            {                log.debug(Messages.getString("ResponseOverrideFilter.parameternotfound")); //$NON-NLS-1$            }            // don't filter!            filterChain.doFilter(servletRequest, servletResponse);            return;        }        HttpServletRequest request = (HttpServletRequest) servletRequest;        BufferedResponseWrapper wrapper = new BufferedResponseWrapper13Impl((HttpServletResponse) servletResponse);        Map contentBean = new HashMap(4);        if (buffer)        {            contentBean.put(TableTagParameters.BEAN_BUFFER, Boolean.TRUE);        }        request.setAttribute(TableTag.FILTER_CONTENT_OVERRIDE_BODY, contentBean);        filterChain.doFilter(request, wrapper);        ExportDelegate.writeExport((HttpServletResponse) servletResponse, servletRequest, wrapper);    }    /**     * {@inheritDoc}     */    public void destroy()    {        // nothing to destroy    }}