name.martingeisse.admin.navigation.NavigationMountedRequestMapper.java Source code

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Here is the source code for name.martingeisse.admin.navigation.NavigationMountedRequestMapper.java

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/**
 * Copyright (c) 2011 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.admin.navigation;

import org.apache.commons.lang3.StringUtils;
import org.apache.wicket.core.request.mapper.MountedMapper;
import org.apache.wicket.request.Url;
import org.apache.wicket.request.component.IRequestablePage;
import org.apache.wicket.request.mapper.parameter.PageParameters;
import org.apache.wicket.request.mapper.parameter.PageParametersEncoder;

/**
 * This mapper is used to mount pages based on navigation nodes. It creates
 * a "fake" page parameter for the navigation path that can be used by
 * the page. The primary use is to allow the page to return this path for
 * back-mapping the page to the navigation tree to mark the "current
 * location" in navigation panels.
 * 
 * When bookmarkable page links generate their URL, this mapper senses
 * the fake page parameter and returns its mounted path only if this
 * parameter matches. That is, a bookmarkable page link will use the
 * mount point generated from a navigation node if that parameter is
 * included, and not use that mount point if the parameter is absent
 * (some other explicit mount point or the default mount point for
 * bookmarkable pages will kick in if that happens).
 * 
 * Note that this mapper does not work for the root URL. To mount an
 * arbitrary page at the root URL and still have it return the root
 * navigation path, subclass that page and implement {@link INavigationLocationAware}
 * manually.
 * 
 * This mapper also allows to specify page parameters that are implicitly
 * added when a request is mapped to a page, and removed when a page
 * class / parameters pair is mapped to an URL. This allows a
 * navigation path (and its URL) to represent parameter assignments
 * not explicitly present in the URL.
 */
public final class NavigationMountedRequestMapper extends MountedMapper {

    /**
     * the parametersEncoder
     */
    private final MyParametersEncoder parametersEncoder;

    /**
     * Constructor.
     * @param navigationPath the navigation path, which is also the mount path
     * @param pageClass the page class to mount
     */
    public NavigationMountedRequestMapper(final String navigationPath,
            final Class<? extends IRequestablePage> pageClass) {
        this(navigationPath, pageClass, new MyParametersEncoder(navigationPath));
    }

    /**
     * Helper constructor to get access to the parameters encoder.
     */
    private NavigationMountedRequestMapper(final String navigationPath,
            final Class<? extends IRequestablePage> pageClass, final MyParametersEncoder parametersEncoder) {
        super(navigationPath, pageClass, parametersEncoder);
        this.parametersEncoder = parametersEncoder;
    }

    /**
     * Getter method for the navigationPath.
     * @return the navigationPath
     */
    public String getNavigationPath() {
        return parametersEncoder.getNavigationPath();
    }

    /**
     * Getter method for the implicitParameters.
     * @return the implicitParameters
     */
    public PageParameters getImplicitParameters() {
        return parametersEncoder.getImplicitParameters();
    }

    /* (non-Javadoc)
     * @see org.apache.wicket.request.mapper.MountedMapper#buildUrl(org.apache.wicket.request.mapper.AbstractBookmarkableMapper.UrlInfo)
     */
    @Override
    protected Url buildUrl(final UrlInfo info) {
        /* This methods performs an additional check so it only maps page/parameter combinations
         * back to URLs that have the implicit navigation path parameter set to the value
         * stored in this mapper.
         */
        if (StringUtils.equals(getNavigationPath(), NavigationUtil.getParameterValue(info.getPageParameters()))) {
            return super.buildUrl(info);
        } else {
            return null;
        }
    }

    /**
     * Customized {@link PageParametersEncoder} implementation.
     */
    private static class MyParametersEncoder extends PageParametersEncoder {

        /**
         * the navigationPath
         */
        private final String navigationPath;

        /**
         * the implicitParameters
         */
        private final PageParameters implicitParameters;

        /**
         * Constructor.
         */
        MyParametersEncoder(final String navigationPath) {
            this.navigationPath = navigationPath;
            this.implicitParameters = new PageParameters();
        }

        /**
         * Getter method for the navigationPath.
         * @return the navigationPath
         */
        public String getNavigationPath() {
            return navigationPath;
        }

        /**
         * Getter method for the implicitParameters.
         * @return the implicitParameters
         */
        public PageParameters getImplicitParameters() {
            return implicitParameters;
        }

        /* (non-Javadoc)
         * @see org.apache.wicket.request.mapper.parameter.PageParametersEncoder#decodePageParameters(org.apache.wicket.request.Request)
         */
        @Override
        public PageParameters decodePageParameters(final Url url) {
            PageParameters parameters = super.decodePageParameters(url);
            if (parameters == null) {
                parameters = new PageParameters();
            }
            for (final String key : implicitParameters.getNamedKeys()) {
                parameters.remove(key);
            }
            parameters.mergeWith(implicitParameters);
            NavigationUtil.setParameterValue(parameters, navigationPath);
            return parameters;
        }

        /* (non-Javadoc)
         * @see org.apache.wicket.request.mapper.parameter.PageParametersEncoder#encodePageParameters(org.apache.wicket.request.mapper.parameter.PageParameters)
         */
        @Override
        public Url encodePageParameters(final PageParameters pageParameters) {
            final PageParameters copy = new PageParameters(pageParameters);
            NavigationUtil.setParameterValue(copy, null);
            for (final String key : implicitParameters.getNamedKeys()) {
                copy.remove(key);
            }
            return super.encodePageParameters(copy);
        }

    }

}