org.xchain.namespaces.servlet.ResultCommand.java Source code

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Here is the source code for org.xchain.namespaces.servlet.ResultCommand.java

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/**
 *    Copyright 2011 meltmedia
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.xchain.namespaces.servlet;

import javax.servlet.ServletResponse;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.Result;
import javax.xml.transform.stream.StreamResult;

import org.apache.commons.jxpath.JXPathContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xchain.Command;
import org.xchain.annotations.Attribute;
import org.xchain.annotations.AttributeType;
import org.xchain.annotations.Element;
import org.xchain.annotations.PrefixMapping;
import org.xchain.namespaces.sax.PipelineCommand;
import org.xchain.framework.util.ContentType;

/**
 * Set the current Pipeline result to be written out to a ServletResponse.  If the <code>media-type</code> attribute is not
 * specified then the media type of the current Pipeline will be used.  If the Pipeline does not specify a media type and
 * the <code>media-type</code> attribute is not specified then the media type will default to <code>text/html</code>.
 * 
 * <code class="source">
 * &lt;xchain:result xmlns:xchain="http://www.xchain.org/container/1.0"/&gt;
 * </code>
 *
 * @author Mike Moulton
 * @author Devon Tackett
 * @author Christian Trimble
 * @author Jason Rose
 * @author Josh Kennedy
 */
@Element(localName = "result")
public abstract class ResultCommand implements Command {

    public static Logger log = LoggerFactory.getLogger(ResultCommand.class);

    /**
     * The media type for the response. 
     */
    @Attribute(localName = "media-type", type = AttributeType.JXPATH_VALUE)
    public abstract String getMediaType(JXPathContext context);

    public abstract boolean hasMediaType();

    /**
     * The location of the ServletResponse. 
     */
    @Attribute(localName = "result", type = AttributeType.JXPATH_VALUE, defaultValue = "$"
            + Constants.DEFAULT_PREFIX + ":" + Constants.RESPONSE, defaultPrefixMappings = {
                    @PrefixMapping(uri = Constants.URI, prefix = Constants.DEFAULT_PREFIX) })
    public abstract ServletResponse getResult(JXPathContext context);

    /**
     * The flag to disable response caching.
     */
    @Attribute(localName = "disable-caching", type = AttributeType.JXPATH_VALUE, defaultValue = "'false'")
    public abstract Boolean getDisableCaching(JXPathContext context);

    @Attribute(localName = "request", type = AttributeType.JXPATH_VALUE, defaultValue = "$"
            + Constants.DEFAULT_PREFIX + ":" + Constants.REQUEST, defaultPrefixMappings = {
                    @PrefixMapping(uri = Constants.URI, prefix = Constants.DEFAULT_PREFIX) })
    public abstract ServletRequest getRequest(JXPathContext context);

    public boolean execute(JXPathContext context) throws Exception {
        ServletResponse response = getResult(context);

        // set the result in the pipeline config's composite stage
        Result result = new StreamResult(response.getOutputStream());
        PipelineCommand.getPipelineConfig().getCompositeStage().setResult(result);

        // set the content type for the response
        ContentType contentType;

        String requestedMediaType = hasMediaType() ? getMediaType(context)
                : PipelineCommand.getPipelineConfig().getCompositeStage().getMediaType();
        String requestedEncoding = PipelineCommand.getPipelineConfig().getCompositeStage().getEncoding();

        String charset = ContentType.DEFAULT_CHARSET;
        if (requestedEncoding != null) {
            charset = ContentType.ATTR_CHARSET + "=" + requestedEncoding;
        }

        if (requestedMediaType != null) {
            contentType = new ContentType(requestedMediaType + ";" + charset);
        } else {
            contentType = ContentType.TEXT_HTML;
        }

        // If the browser does not accept XHTML and we are requesting XHTML, default to HTML
        String acceptHeader = ((HttpServletRequest) getRequest(context)).getHeader("Accept");
        if (contentType.mediaTypeMatch(ContentType.TEXT_XHTML)
                && !ContentType.acceptsContentType(acceptHeader, ContentType.TEXT_XHTML)) {
            contentType = ContentType.TEXT_HTML;
        }

        response.setContentType(contentType.toString());

        if (getDisableCaching(context)) {
            disableCaching((HttpServletResponse) response);
        }

        return false;
    }

    protected void disableCaching(HttpServletResponse response) {
        response.setHeader("Cache-Control", "must-revalidate");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Cache-Control", "no-store");
        response.setHeader("Paragma", "no-cache");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0L);
    }
}