com.day.cq.commons.servlets.AbstractPredicateServlet Maven / Gradle / Ivy

/*
 * Copyright 1997-2008 Day Management AG
 * Barfuesserplatz 6, 4001 Basel, Switzerland
 * All Rights Reserved.
 *
 * This software is the confidential and proprietary information of
 * Day Management AG, ("Confidential Information"). You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Day.
 */
package com.day.cq.commons.servlets;

import com.day.cq.commons.predicate.PredicateProvider;
import com.day.cq.commons.predicate.ResourceFilter;
import org.apache.commons.collections.Predicate;
import org.apache.commons.collections.functors.AnyPredicate;
import org.apache.commons.collections.functors.TruePredicate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Reference;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.ServletException;
import java.io.IOException;
import java.util.Collection;
import java.util.HashSet;

/**
 * Abstract servlet that retrieves the predicates from the request.
 */
@Component(metatype = false, componentAbstract = true)
abstract public class AbstractPredicateServlet extends SlingAllMethodsServlet {

    /**
     * default path parameter name
     */
    public static final String PATH_PARAM = "path";
    /**
     * default name for the predicate parameter
     */
    public static final String PREDICATE_PARAM = "predicate";
    /**
     * default name for the filter parameter
     */
    public static final String FILTER_PARAM = "filter";
    private static final long serialVersionUID = 6457830085969491553L;
    /**
     * default log
     */
    private final Logger log = LoggerFactory.getLogger(AbstractPredicateServlet.class);

    @Reference
    private PredicateProvider provider;

    /**
     * {@inheritDoc}
     * 
     * Calls {@link #doGet(SlingHttpServletRequest, SlingHttpServletResponse, Predicate)}.
     */
    @Override
    protected void doGet(SlingHttpServletRequest request,
                         SlingHttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response, getPredicate(request));
    }

    /**
     * Handles the HTTP GET method
     *
     * @param request   The HTTP request
     * @param response  The HTTP response
     * @param predicate the predicate retrieved from the request
     * @throws ServletException if a servlet error occurs
     * @throws IOException      if an I/O error occurs
     */
    protected void doGet(SlingHttpServletRequest request,
                         SlingHttpServletResponse response,
                         Predicate predicate)
            throws ServletException, IOException {
        handleMethodNotImplemented(request, response);
    }

    /**
     * Returns the index of the first selector that should be considered when
     * retrieving the predicates for this servlet.
     *
     * @return Always {@link Integer#MAX_VALUE}
     */
    protected int selectorPredicateStart() {
        return Integer.MAX_VALUE;
    }

    /**
     * Returns the predicate retrieved from the given request. the predicates
     * are retrieved from the request selectors and the request parameter values
     * of the {@value #PREDICATE_PARAM}. those predicates form an
     * {@link AnyPredicate}. If no predicates are specified in the request a
     * {@link TruePredicate} is returned.
     * 
     * Note: the {@value #FILTER_PARAM} parameters are used to add {@link ResourceFilter}
     * predicates. although this is discouraged because java class names should
     * never be passed over the wire.
     *
     * @param request servlet request
     * @return predicate
     */
    public Predicate getPredicate(SlingHttpServletRequest request) {

        // get predicates
        Predicate predicate = TruePredicate.INSTANCE;
        if (provider == null) {
            log.warn("Predicate provider not bound.");
        } else {
            Collection predicates = new HashSet();

            // add selector predicates
            String[] selectors = request.getRequestPathInfo().getSelectors();
            for (int i = selectorPredicateStart(); i < selectors.length; i++) {
                Predicate p = provider.getPredicate(selectors[i]);
                if (p == null) {
                    log.warn("Unable to retrieve predicate " + selectors[i]);
                } else {
                    predicates.add(p);
                }
            }

            // add request param predicates
            if (request.getParameterMap().containsKey(PREDICATE_PARAM)) {
                for (String pred : request.getParameterValues(PREDICATE_PARAM)) {
                    Predicate p = provider.getPredicate(pred);
                    if (p == null) {
                        log.warn("Unable to retrieve predicate " + pred);
                    } else {
                        predicates.add(p);
                    }
                }
            }

            // add request param filters
            if (request.getParameterMap().containsKey(FILTER_PARAM)) {
                ClassLoader loader = this.getClass().getClassLoader();
                for (String filter : request.getParameterValues(FILTER_PARAM)) {
                    try {
                        predicates.add(new ResourceFilter(loader.loadClass(filter)));
                    } catch (ClassNotFoundException e) {
                        log.warn("Requested filter class {} not found.", filter);
                    }
                }
            }

            if (!predicates.isEmpty()) {
                predicate = AnyPredicate.getInstance(predicates);
            }
        }
        return predicate;
    }


}